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Shaaban Kitindi FundiSpring, 2004

Executive Summary

Despite the growing recognition of lead abatement as an intervention for reducing the risk of lead exposure to children, very few scientists have attempted to review data on its effectiveness. This study reviews the current information on residential lead abatement procedures in order to determine whether these abatement strategies are an effective method to prevent lead exposure in children, as measured by blood lead levels.

A standardized protocol for searching, acquiring, and extracting study data and synthesizing results across studies was used. The criteria for studies to be included in the review were: (1) includes children under the age of 6 years, (2) conducted in the United States, (3) published between January 1990 and March 2004, and (4) have a pre/post or multi arm study design. Nineteen studies were found that met the inclusion criteria. Three of the nineteen identified studies looked at soil abatement, four looked at paint abatement, ten looked at dust abatement, and two studies used a mixture of soil and dust abatement. No studies looking at the effect of monitoring tap water for lead on children’s lead exposure were identified in this review. The studies varied greatly in terms of their sample size, study design, and methods of data collection.

A review of studies looking at the effectiveness of residential lead abatement strategies at reducing blood lead levels in children found mixed results. Soil abatement strategies appear to be most effective when the soil concentration is quite high (>1000ppm) and when children’s exposure to lead is primarily through contaminated soil and not household dust. The studies regarding lead paint abatement also show mixed results. Amitai, et al. found that doing abatement while children were living in the home actually caused a short term increase in mean blood lead levels. For this reason, it may be more effective to do primary prevention by abating homes before occupancy than to wait to do abatement after the children have already been exposed. There is also evidence that lead paint abatement may be most effective for children with very high lead blood levels (>25μg/dL) suggesting that this strategy may make more sense as a targeted intervention. Finally, the data suggest that residential dust abatement strategies are most effective when done multiple times as household dust tends to re-accumulate after short periods of time. In addition, carpets and upholstery remain important reservoirs for lead exposure and new techniques need to be developed to better clean these potential sources of lead exposure.

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Table of Contents

Introduction…………………………………………………………………………………..3

Figure 1. Pathways of Lead Exposure in the Residential Environment………………….3Table 1. Health Effects of Various Blood Lead Concentrations (in μg/dL) in Children…7

Methods………………………………………………………………………………………10

Results………………………………………………………………………………………..11

Figure 2. Flowchart Showing the Selection of Articles ………………………………....12Interventions to reduce children’s lead exposure from contaminated soil……………….13Interventions to reduce children’s lead exposure from residential deteriorating paint…..15Interventions to reduce children’s lead exposure from residential dust……………….....16Interventions targeting multiple pathways……………………………………………….19

Discussion…………………………………………………………………………………….20Policy Recommendations………………………………………………………………...20Research Recommendations……………………………………………………………...22

Conclusions…………………………………………………………………………………...23

Appendix A. Conceptual Framework Illustrating Factors Associated with Children’s Elevated Blood Levels and the Interventions Used to Mitigate the Problem…………………………..29

Appendix B. Table Reviewing the Evidence for the Effectiveness of Residential Lead Abatement Strategies………………………………………………………………………….30

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Introduction

Lead is one of the most widely dispersed toxic substances in recent human history (1).

Although blood lead levels in children in the United States have decreased in recent years due to

legislation banning lead in gasoline and paint products, a large number of children continue to be

exposed to unacceptably high levels of lead in their environments (2,3). One potential reason for

this continued lead exposure is that lead is a highly stable element and once in the environment it

can remain for many decades (4). Recent evidence from an estuary system in San Francisco

shows that the estuary has recycled and retained gasoline lead in the San Francisco Bay

sediments since lead in gasoline was outlawed in the 1970s (4). Thus, lead can continue to cause

environmental and health effects long after the source of the contamination has ended.

Lead can enter the environment from a number of sources. These pathways are

illustrated in Figure 1.

Figure 1. Pathways of Lead Exposure in the Residential Environment

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Interior Lead-Based Paint

Interior DustExterior Solid Dust

Exterior Paint Hands, toys,

food, and other mouthable objects

Child

Lead in Tap Water

Community Sources


Community sources of lead include lead mining, milling and smelting industries (3-6).

Lead is introduced into the soil when it is emitted as an aerosol from these industrial sources into

the atmosphere and falls to the ground via rainfall and dry deposition (7). Therefore, children

who live near mining industries are at increased risk for elevated blood lead levels (6,8). Since

1978, the Environmental Protection Agency (EPA) has set the national ambient air quality

standard (NAAQS) for lead at 1.5μg/m3. Under the policy, each state has the ability to determine

how to achieve this level through its own state implementation plan. Substantial reductions in

industrial sources of lead emissions to the atmosphere have resulted from these regulations (9).

Even though lead in gasoline has been slowly phased out since the introduction of

catalytic converters in US automobiles in 1973, soil is still contaminated with lead from gasoline,

especially the soil around heavily-used streets and roads (10). As the use of lead in gasoline has

fallen, there has been a corresponding decrease in average blood lead levels from a high of

15.5μg/dL in 1978 to an average of 7 μg/dL in 1980 (9). With the 1990 amendment of the Clean

Air Act which bans the manufacture, sale, or introduction after 1992 of any engine that requires

leaded gasoline and the prohibition of all leaded gasoline for highway use, blood lead levels have

continued to fall (9). A nationally representative survey of 13,201 persons found that the overall

mean blood level for the US population was 2.8 μg/dL in 1991 (10). However, the blood levels

for children 1 to 5 years of age remained high. Approximately 1.7 million children or 8.9% of

U.S. children had blood lead levels of 10 μg/dL or greater (10). In fact, since lead does not break

down once it enters the environment; contaminated soil will continue to be a risk factor for

elevated blood levels among children for many years to come (1).

Lead can also enter the soil from flaking or chipping of exterior lead based paint (3) and

from disintegration of old lead-soldered cans (3). Since the 1980s, the Food and Drug

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Administration and food processors in the United States have cooperated in a voluntary program

to eliminate lead-soldered cans (3). However, canned foods from foreign countries are not

regulated by this voluntary program and may contain lead-soldering (3). In addition, these cans

require centuries to decompose and therefore, lead from these cans remains a potential source of

lead contamination in the environment (5).

Children can also be exposed to lead through drinking water. Lead found in tap water is

usually from the corrosion of lead-containing materials found in water distributions systems and

household plumbing (12). Exposure to lead in tap water has been reduced by measures taken

during the last two decades under requirements of the Safe Drinking Water Act and other

regulations by the Environmental Protection Agency (13). Currently, EPA regulations apply

only to public water systems and require those systems to monitor tap water for lead (13). Lead

levels are reduced by treating the water to make it less corrosive, and in some cases, replacing

water-service lines that contain lead pipes (13). These regulations, however, do not apply to the

over 40 million households supplied by private well water and, consequently, in most

jurisdictions there is no monitoring for lead in drinking water supplied by private wells (13).

As lead exposures through industrial and gasoline emissions and drinking water have

declined in recent years, the relative importance of exposure to lead in household dust and urban

soil has increased. Lead in soil can contribute to high levels of lead in household dust when it is

tracked inside by shoes, brought home from the workplace, produced as a result of home

renovation, or generated by hobbies that involve lead (1). Lead can also get into household dust

from the flaking and chipping of lead-based paint (14). Lead can be dispersed when paint is

disturbed during demolition (15), remodeling (15), paint removal (14), or preparation of painted

surfaces for repainting (13). Older homes in poor condition have been shown to have much

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higher dust lead levels than older homes in good condition, suggesting that the condition of the

house is an important risk factor for lead in household dust (16).

Lead based paint is currently viewed as the predominant contributor to elevated blood

lead levels (>10 μg/dL) in U.S. children. It has been estimated that approximately 42 million

homes in the United States contain lead-based paint, with about 12 million children under 7 years

exposed to lead-paint (13). Although the addition of lead to residential paint was banned in

1978, 74% of dwellings constructed prior to 1980 contain some leaded paint (13). Furthermore,

the amount of lead in paint in homes built before 1950 is higher than in homes built later but

prior to the ban on leaded house paint. For example, 90% of homes built before 1940 have paint

containing more than 1 mg/cm2 of lead, compared with 62% of dwellings built between 1960 and

1979 (13). Children can be exposed to lead from paint either directly by ingesting the paint chips

or indirectly by mouthing objects that have been covered in dust that contains lead (16).

Despite recent policy changes that have led to a reduction in the general population

exposure to lead toxicity, lead continues to have a major detrimental affect on the health of

young children (9,14). The Centers for Disease Control and Prevention estimates that the range

of children potentially exposed to lead in dust and soil is between 5.9 million to 7.1 million (14)

and that 1.7 million or 8.9 % of U.S. children 5 years and younger have blood lead levels

exceeding 10 μg/dL, the point at which lead poisoning is said to occur (10). Lead is especially

hazardous to young children under the age of 6 because their still developing nervous systems

are particularly susceptible to the neurotoxic effects of lead (13). Moreover, the efficiency of

gastric absorption of lead is greater in children than in adults (14). The normal play activities of

children, such as crawling or playing on the floor, also put them at greater risk for exposure to

dust and soil that may be contaminated with lead (9). Similarly, children are more likely to put

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things in their mouth, thereby increasing the opportunity for soil and dust ingestion (9). The total

tolerable daily intake of lead is 6μg per day and may be easily exceeded by children who play in

outdoor environments with heavy concentrations of lead in the soil (>500ppm) (18).

Lead exposure is linked to several major health problems in young children. These are

summarized in table 1.

Table 1. Health Effects of Various Blood Lead Concentrations (in μg/dL) in ChildrenBlood Lead

Concentration (μg/dL)

Health Effects

10 Reduced IQ, impaired hearing, slow growth, behavioral problems20 Impaired nerve function30 Reduced Vitamin D metabolism40 Damage to blood forming system50 Severe stomach cramps

70-100 Severe anemia, kidney damage, severe brain damage>100 Death

Behavioral affects of lead exposure include cognitive deficits (19-20), behavioral

disorders (19-20), and propensity towards violence (19). Biological affects range in severity

according to the level of lead exposure (13) and include slowed growth (19-20), impaired hearing

(18), and reduction in hand-eye coordination (19). At higher levels, lead can cause harm to the

child’s kidney, bone marrow, and other bodily systems (13,19). At very high levels

(>100μg/dL), lead can cause coma, convulsion, and death (13,19). In addition, lead can interact

with other metals in the body. For example, lead exposure causes a depletion of calcium and

zinc stores, and this depletion can result in enhanced lead uptake and distribution of lead in the

body (14,21). Bradman and colleagues also found that iron-deficient children may absorb lead at

a higher fraction than non-iron deficient children (20). Thus, defects in nutrition can enhance

lead absorption and retention and the risk of toxicity from lead (14, 20-21). This is especially

important as children of lower socioeconomic status—who are often at risk for nutritional

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deficiencies—have been shown to be more likely to live in older housing where they may be at

increased risk for exposure to lead (21).

Research has pointed to several other risk factors that put certain children at greater risk

for lead poisoning. The most common cited risk factors are being a minority of either African

American or Hispanic origin (19, 21-24), of lower socioeconomic status (21-23, 25), living in

housing built before 1950 (19, 22), and living in urban areas (19, 21). In addition, low parental

income and parental education level have also been associated with increased risk of lead

exposure among children (21, 25). Because African American children tend to be of lower

socioeconomic status, they often live in older housing in inner city neighborhoods where they

experience almost twice the level of blood lead as white children (21). Other risk factors

associated with high blood lead levels in children are age of the child (exposure declines as child

ages) (24), living near a mining/smelting industry (5, 25-26), the pica behavior of the child

(tendency to put things in the mouth) (24-25), and number of hours spent playing outside (24).

Appendix A presents a conceptual model summarizing these risk factors and showing

how they interact with the sources of lead exposure in children. Figure 2 also illustrates the most

common interventions used to reduce children’s lead exposure from residential sources and

shows where they are located in the exposure pathway. For children with blood lead levels >45

μg/dL, the CDC recommends immediate treatment with a chelating agent to reverse cognitive

and neurobehavioral deficits and to mitigate the damage of lead poisoning on the kidneys and

other organs. Treatment with chelating agents is very expensive costing between $1000 per day

or more if the child is hospitalized (13). In addition to the high costs, medical management does

not attack the source of the lead exposure and therefore, does not prevent future children from

being exposed to the effects of lead. Therefore, in recent years, increasing attention has been

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focused on primary prevention of lead exposure. These primary prevention interventions include

soil abatement, dust and paint abatement, and monitoring of tap water. These interventions and

their related costs are reviewed below.

Soil Abatement—Soil abatement interventions usually consist of removing 6 inches of

top soil from the entire area of interest, placing a water-permeable geotextile fabric over the

exposed subsurface, and then covering the fabric with 8 in. of clean soil and ground cover (27). It

is generally recommended for those areas with a lead concentration in soil >500ppm (5). The

cost of the intervention is around $9600 per property abated (27).

Monitoring of Tap Water for Lead—Environmental Protection Agency regulations

require all public water systems to monitor their tap water for lead and to implement public

education and other measures to reduce lead levels in drinking water if they exceed 15 g/L in

more than 10% of household samples (12). Lead is reduced in water by replacing lead-

containing pipes and/or by treating supplied water to reduce its corrosiveness (13).

Dust and Paint Abatement—Interior dust abatement usually consists of vacuuming walls,

woodwork, floors, and rugs with a high efficiency filter vacuum (HEPA), and wiping surfaces

with wet cloths and furniture with oil-treated cloths (28-29). In addition, interior loose-paint

stabilization is often done which consists of HEPA vacuuming and washing areas of loose paint

on walls and woodwork with trisodium phosphate, and painting window wells with primer (28).

The average cost for this type of intervention is $4500/unit (30).

Lead paint abatement involves removing or covering lead paint from accessible

mouthable surfaces 5 feet or less from the ground and removing or covering exterior lead paint

(28-29). Paint abatement is recommended in homes with lead levels of 100μg/ft2 for floors,

500μg/ft2 for interior window sills, and 800 μg/ft2 for window troughs (28). This type of

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intervention is more expensive than the more transitory dust abatement procedures with an

average cost of $9000 per unit (13).

These interventions have been increasingly employed by public health researchers to try

to reduce residential exposure to lead among young children. Yet, despite this interest in these

abatement procedures there have few attempts to systematically review the strength of evidence

for the effectiveness of these interventions at reducing blood lead levels in children. This paper

reviews the current information on residential lead abatement procedures in order to determine

whether these abatement strategies are an effective method to prevent lead exposure in children,

as measured by blood lead levels.

Methods

Aim and Research Question

The purpose of this review study is to evaluate the effectiveness of residential lead

abatement strategies in reducing lead exposure among children. The question of interest for this

review is: “Which lead abatement strategies are successful in reducing children’s exposure to

lead, as measured by blood lead levels?”

Search Strategy

All articles published between January 1990 and March 2004 were reviewed. Articles

were identified through a comprehensive search of three electronic databases: PubMed, the

National Library of Medicine’s Gateway, and Lexis Nexis. To identify unpublished documents,

several websites were searched including the Environmental Protection Agency website, the

Centers for Disease Control website, and the Department of Health and Human Services website.

Any article that qualified during these searches was then retrieved from the library and the

bibliography searched for any additional references. The search terms used during the computer-

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based searches include: residential lead abatement strategies; lead exposure and children; lead

abatement and children; and lead exposure and policies.

Inclusion Criteria

To be eligible for this review the article must have met the following four criteria: 1)

include children less than 6 years of age; 2) been conducted in the United States; 3) published

between 1990 and 2004; and 4) have either a pre/post or multi-arm study design. In addition, the

study must have assessed the effect of the lead abatement strategy on children’s blood lead

levels. Only studies published in English were reviewed for this study.

Data Collection

Data from the studies was extracted using a detailed coding strategy. All study

information and data were recorded in a table in Microsoft Word.

Results

Of the 136 articles located through electronic database and secondary searching 19

studies met the inclusion criteria (see figure 2). Fifteen of the nineteen studies were conducted in

the Northeast (New York, Maryland, New Jersey, and Massachusetts); three were conducted in

the central part of the country (Wisconsin, Missouri, Utah); and the final study was conducted in

multiple settings including Cincinnati, Newark, Baltimore, and Philadelphia. Eighteen of the

nineteen studies were conducted in urban areas. Only one study—looking at a community near a

lead smelter—was conducted in a rural area.

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Figure 2. Flowchart Showing the Selection of Articles for the Systematic Review of Abatement Strategies for Reducing Lead Exposure Among Children

The studies reported vary greatly in terms of their sample size, study design, and methods

of data collection (Appendix B). Nine of the nineteen studies had a randomized study design

with both an intervention and control group (9/19, 47.4%) (28,35-39,42,44-45). Six studies used

a pre/post design with no control group (6/19, 31.6%) (27, 31-34, 37) and two studies used a

retrospective design (2/19,10.5%) comparing those children whose homes were and were not

abated (40-41). The final two studies had a non-randomized multi-arm study design with an

intervention and control group (2/19, 10.5%) (43, 46).

Using Appendix A as a guide, we identified three studies dealing with soil abatement (5,

44-45), four studies of paint abatement (31, 33-34, 41), ten studies of dust abatement (32, 35-40,

42-43, 46), and two studies that used a mixture of soil and dust abatement (27-28). No studies

looking at the effect of monitoring tap water for lead on children’s lead exposure were identified

in this review. A summary of the results of these studies is presented below (see Appendix B).

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Interventions to reduce children’s lead exposure from contaminated soil

Of the three studies looking at the effectiveness of soil abatement in reducing children’s

blood lead levels, two showed a significant reduction in children’s blood lead levels and one

showed no significant change.

In Baltimore, Farrell et al. randomly assigned 408 children (aged 6 months to 6 years) to

either an intervention group (whose homes received exterior paint stabilization followed by the

removal and replacement of contaminated soil) or a control group (whose homes underwent

exterior paint stabilization but no soil abatement) (44). Only 54% of homes at baseline had soil

samples with a lead concentration above 1000ppm. At baseline the blood lead levels for the

intervention group were 9.6 μg/dL. One year post-abatement these levels had remained

unchanged at 9.7 μg/dL. In the control group, baseline levels were 9.1 μg/dL which decreased to

8.4 μg/dL at one-year post-abatement. The change in blood lead levels comparing the

intervention and control group one-year post abatement was not significant. Results of

multivariate analysis showed no significant difference in the mean blood lead level of the two

groups at follow-up (44).

In Boston, Weitzman et al. tested the hypothesis that a reduction of 1000ppm or more of

lead in soil accessible to children (mean age 31.6 months) would result in a decrease of at least

0.14mμmol/L (3μg/dL) in blood lead levels (45). The median surface soil lead concentration at

baseline was 2075ppm. Children were randomly assigned to one of three groups: the study

group, whose homes received soil and interior dust abatement and loose paint removal;

comparison group A whose homes received interior dust abatement and loose paint removal; and

comparison group B, whose homes received only interior loose paint removal. The mean blood

lead level of the study group declined 1.53 μg/dL more than that of group A and 1.92 μg/dL

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more than that of group B. The magnitude of the decline independently associated with soil

abatement ranged from 0.8 to 1.6 μg/dL after controlling for potential confounders (p=0.02).

However, despite the statistical significance the authors concluded these differences were not of

clinical significance. Furthermore, they suggested that although soil lead abatement was

associated with a decline in children’s blood lead levels, children who lived in dwellings with

consistently elevated floor levels of leaded dust derived no benefit from soil abatement (45).

The only rural study in the review was conducted by Lanphear and colleagues looking at

the effect of soil abatement on blood lead levels of children living near a former smelting and

mining operation in Utah (5). The children ranged in age from 6 to 72 months and lived in

homes with an average soil lead concentration >500ppm (5). The results of the study showed a

significant decline in lead and arsenic in soil and interior dust in homes that underwent soil

abatement (p<0.05). The blood lead levels of children aged 6 to 72 month who lived in soil

abated housing declined 42.8% faster than children who lived in unabated housing (p = 0.14). In

children 6 to 36 months, the decline was 45.4% faster (p = 0.03). The authors estimated that the

reduction in blood lead for children aged 6 to 36 months was 3.5 μg/dL for every 1,000 ppm

reduction in soil lead concentration (95% CI: 2.4 μg/dL to 4.6 μg/dL). This finding led them to

conclude that soil abatement was associated with a significant decline in children’s blood lead

levels (5).

There are several possible reasons for why the urban studies failed to show an effect for

soil abatement. First, both of these studies were performed in scattered homes that were not

contiguous, so that children may have experienced continued exposure from nearby homes.

Second, these studies enrolled children whose primary exposure to lead was through dust from

lead paint not from soil contamination. This is in contrast to the rural Utah study which did

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show soil abatement to be effective. In that study, children’s main exposure to lead was through

contaminated soil.

In summary, soil abatement appears to have mixed results in reducing children’s blood

lead levels. It appears to be more effective in children whose primary exposure to lead is

through contaminated soil and not household dust and/or lead paint. In addition, it appears to be

more effective in areas where the soil lead concentration is very high (>1000ppm).

Interventions to reduce children’s lead exposure from residential deteriorating paint

Interventions to reduce children’s exposure to deteriorating paint in their homes include

the safe repair of non-intact leaded paint, the safe repair or replacement of windows to prevent

abrasion of leaded paint, and the safe removal (stripping) of leaded paint from components left in

the home (13). In a retrospective study comparing children whose homes had and had not

undergone remediation for lead-based paint, Staes, et al. found that the geometric mean blood

lead level decreased 23% among children living in remediated dwellings and 12% among

children in non-remediated dwellings (p=0.07) (41). The effect of remediation was greater

among children whose blood lead levels at diagnosis were ≥35 μg/dL (-22%) than among those

whose blood lead levels at diagnosis were between 25 and 34 μg/dL (1%), suggesting that the

intervention was most effective for children with very high exposures to lead (41).

Two studies conducted in Baltimore by Farfel and colleagues also examined the

effectiveness of lead paint abatement (33-34). The abatement procedure involved (i) treatment

of lead painted surfaces above and below 4fts from the floor, including interior and exterior

components of windows. (ii) sealing or covering of wooden floors. (iii) procedure for

containment of dust during abatement. (iv) final clean up using a high efficiency particle air

(HEPA) vacuum. Although they found significant reductions in house dust levels in the short

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term, these reductions were not maintained long term (6-months post-abatement). In addition,

there was no long term reduction in children’s lead levels. The authors suggest that paint

abatement by itself is not effective unless combined with regular household dust abatement (33-

34).

In a study in Boston with children younger than 6 years, Amitai and colleagues found that

blood lead levels actually went up during deleading using lead paint abatement (42.1 μg/dL

during deleading vs. 36.4 μg/dL at baseline, (p<0.001)), although these levels went down shortly

after deleading (to 33.5 μg/dL) (31). They further found that the method of deleading was an

important factor in determining how high the blood lead levels of children rose during the

deleading process. Replacing or permanently covering painted surfaces was associated with the

lowest average increase (2.25±2.4 μg/dL), followed by dry scraping and sanding (9.1±2.4

μg/dL). The use of heat guns or propane torches to remove paint was associated with very high

increases in children’s blood lead levels (35.7.1±10.8 μg/dL) or 98% higher than the pre-

deleading levels (31). This study suggests that careful consideration needs to be given to the

method used for lead paint abatement to prevent causing children to experience increased

exposure to lead during the deleading process.

In summary, paint abatement strategies appear to be most effective with children who

have high blood lead levels. Caution should be taken when choosing the method of abatement as

some methods cause substantial increase in children’s blood lead levels during the abatement

process.

Interventions to reduce children’s lead exposure from residential dust

Four studies assessed the efficacy of household dust control by professional cleaners (32,

38-39, 46). Two of the four studies had intensive professional cleaning (i.e. two trained cleaners

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wet mopping floors and wet wiping horizontal surfaces for 2 hours every 2-3 weeks) (38-39).

Both studies showed significant reductions in mean blood lead levels. In the first study, Rhoads

and colleagues found a 17-18% decrease in the mean blood lead of children in the intervention

group and no change among the children in the control group (39). In the second study, Lioy and

colleagues found a 75% reduction in the amount of lead observed on window sills in the

intervention group compared to the control group (38). Since trained cleaners conducted the

interventions, these effect sizes are probably the optimum that can be achieved. The remaining

two studies failed to show that dust control reduced children’s blood lead levels over the long

term (32, 46). Both studies were of a one-time intervention which may have contributed to the

non-significant finding as household dust builds up again after a short time.

Lanphear and colleagues conducted two studies in which cleaning was done by

caregivers as opposed to professional cleaners (35-37). In the first study, 104 children (aged 12

to 31 months) were randomly assigned to an intervention group (received cleaning supplies,

information about cleaning areas that are often contaminated with lead, and a cleaning

demonstration) or to a control group (in which care givers received only a brochure about lead

poisoning prevention). Seven months after enrollment, the median change in blood lead levels

among children in the intervention group was -0.05 μg/dL compared with -0.60 μg/dL among

those in the control group (p=0.50) (35). The authors comment that they were unsure whether

the participants adhered to the study protocol which may have affected their findings.

In the second study by Lanphear and colleagues, 275 children between the ages of 6 and

30 months were randomly assigned to either an intervention group which received cleaning

equipment and up to eight visits by a dust control advisor or a control group (37). Again, the

authors found no significant difference in the mean blood level at the 12, 18, 24, and 48-month

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follow-up between the intervention and control group, which led them to conclude that dust

control as performed by families is not effective in the primary prevention of child lead

exposure.

One study by Schultz and colleagues used a retrospective design to examine the efficacy

of a one hour educational visit in reducing the blood lead levels of children with moderate levels

of lead poisoning (40). Children with elevated blood lead levels between 20 and 24 μg/dL were

found through a retrospective examination of Milwaukee Health Department records. Children

were then randomized to receive an in-home educational visit by a health professional or to be in

a control group. In-home educational visits lasted about an hour and discussed dust clean-up

practices to reduce lead exposure. The study group had a significantly greater mean decline in

blood levels 4.2 μg/dL than the reference group (1.2 μg/dL, p =0.001). This finding led the

authors to conclude that the home educational visits may have helped reduce children’s blood

lead levels. However, there was some question to the validity of their study as there was no way

to ensure that children in the study group were comparable to children in the control group

whose families were often unavailable for outreach visits. Thus, the parental behavior of the

children may be an important confounder in the association between the intervention and the

change in mean blood lead levels.

Most of the above studies focused on cleaning uncarpeted floors. Two studies by Yiin

and colleagues in New Jersey examined the effectiveness of cleaning carpets as an intervention

to reduce blood lead levels in children (42-43). The study found that neither HEPA vacuums nor

conventional vacuums were effective at reducing lead levels on carpets and upholstery below

federal guidelines (42). Furthermore, when the authors compared the efficacy of HEPA

vacuuming in carpeted versus uncarpeted homes, they found a significant reduction of children

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blood lead levels for the uncarpeted home (p =0.004) and no significant change for the carpeted

homes (p =0.0566) (43). This led them to argue that even after professional cleaning, carpets

and upholstery remain an important reservoir for lead contaminated dust.

In summary, studies show that professional cleaning is an effective strategy to reduce

household dust. However, in order to be effective the cleaning must be repeated every 2-3 weeks

to prevent dust from building up again on surfaces. Health education appears to also be effective

although more rigorous studies are needed to prove its efficacy. Carpets and upholstery do not

appear to be effectively cleaned by HEPA vacuuming and remain important sources of lead

exposure for children.

Interventions targeting multiple pathways

Two studies combined residential house dust abatement with soil abatement (27-28). In

these studies children were randomized into two groups: group 1—soil abatement, interior dust

abatement; and interior loose-paint stabilization and group 2—interior loose paint stabilization

only. Soil abatement was conducted at homes that had average surface soil lead levels of at least

1500 ppm. Changes in blood lead levels were observed following paint hazard remediation

alone and in combination with soil abatement. The studies found that lead-based paint

remediation alone was associated with statistically significant blood lead increase of 6.5 μg/dL

over the subsequent 9 months of follow-up but with an increase of only 0.9 μg/dL when

combined with soil abatement (27). Neither intervention reduced blood lead levels in children.

The authors argue that these data give proof to the suggestion that greater emphasis be placed on

primary prevention by abating the homes before occupancy to prevent lead exposure in the first

place.

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Discussion

A review of studies looking at the effectiveness of residential lead abatement strategies at

reducing blood lead levels in children found mixed results. Soil abatement strategies appear to

be most effective when the soil concentration is quite high (>1000ppm) and when children’s

exposure to lead is primarily through contaminated soil and not household dust. The studies

regarding lead paint abatement also show mixed results. Amitai, et al. found that doing

abatement while children were living in the home actually caused a short term increase in mean

blood lead levels. For this reason, it may be more effective to do primary prevention by abating

homes before occupancy than to wait to do abatement after the children have already been

exposed. There is also evidence that lead paint abatement may be most effective for children

with very high lead blood levels (>25μg/dL) suggesting that this strategy may make more sense

as a targeted intervention. Finally, the data suggest that residential dust abatement strategies are

most effective when done multiple times as household dust tends to re-accumulate after short

periods of time. In addition, carpets and upholstery remain important reservoirs for lead

exposure and new techniques need to be developed to better clean these potential sources of lead

exposure.

Policy Recommendations

A review of the literature has pointed to number of policy recommendations for more

adequately addressing the problem of residential lead exposure and children. These are

summarized below:

Reduce the standards for safe dust lead levels in homes—Lanphear and colleagues found

that a substantial proportion of children have blood lead levels in excess of 10μg/dL at dust lead

20


levels considerably lower than current EPA guidance levels (3). These data suggest that the dust

lead standards should be lowered in order to adequately protect children.

Standardize the regulations regarding lead exposure—Currently, there are different

regulations regarding lead abatement at both the federal and state level (47). In addition there

are several different agencies including the U.S. Occupational Safety and Health Administration

(OSHA), the Environmental Protection Agency, and the Department of Housing of and Urban

Development involved in making policies regarding lead exposure and lead abatement. This

often causes conflicting messages and/or policies and may lead to duplication of efforts.

Therefore, there is a real need to standardize these policies across states and jurisdictions in order

to ensure that children receive the most effective abatement procedures. It may be better to have

one agency with jurisdiction over all lead abatement activities.

Formulate a policy for addressing children with moderately elevated blood lead levels—

Currently, there is no consensus on what to do with children who have elevated blood lead levels

between 10-20μg/dL (19). These children do not have levels high enough under current policies

to warrant abatement procedures and/or chelation therapy. However, several studies have shown

that even at small levels of lead exposure, children can experience harmful effects. There is a

real need, therefore, to develop a policy to address the issue of children with moderately elevated

blood lead levels.

Need to target high risk areas for screening—Several studies have shown that minority

children living in urban areas are at much greater risk for elevated blood lead levels than white

children in suburban areas (19,21). Therefore, it is important that health departments forgo

universal screening in order to do targeted screening in high risk areas. With the money saved

21


by targeted screening, it is essential that help be given to landlords and homeowners to support

them in abatement procedures as they can be quite expensive ($4500-$9000 per unit) (27).

Increase compliance monitoring and enforcement of existing regulations—Federal

legislation entitled Title X requires landlords, sellers, and agents to provide lead hazard

information and to disclose information about known lead paint and lead paint hazards to

prospective landowners and tenants. However, a 1998 survey by the Bureau of Census reported

that almost 40% of respondents did not receive this information (13). Therefore, it is essential

that efforts to enforce the disclosure rule need to be increase in order to improve compliance with

this regulation.

Research Recommendations

In addition, to the policy recommendations, several research needs were also identified

during this review. They are outlined below:

Need for more rigorous study designs—Several of these studies had very weak study

designs with either a retrospective design or a pre/post design with no control group. This makes

it difficult to attribute any change in blood lead levels to the intervention. In addition, several

studies did not include randomization which could have led to systematic differences between

the intervention and control group. Therefore, there is a real need to develop more

methodologically sound research trials to evaluate the strength of evidence for the effectiveness

of residential lead abatement strategies at reducing children’s blood lead levels.

Develop and evaluate new cost-effective lead paint hazard control technologies—Several

studies have reported that children’s blood lead levels actually increase during lead paint

remediation (31,34). Therefore, there is a real need for research to develop methods of removing

lead paint in ways that do not generate dust. In addition, current abatement strategies are very

22


expensive and there effectiveness somewhat limited, making their cost-effectiveness ratio

unfavorable. Thus, there is a need to develop new, more cost-effective methods for lead paint

abatement.

Need to assess multifactor interventions—Several studies reported that, in the absence of

interventions to reduce ongoing contamination of dust from disintegrating paint, the effect of

dust control on children’s blood lead levels is modest (35,37,39). Thus, there is a need to

conduct studies that contain multiple components such as dust control, nutritional

supplementation, and health education to determine their effectiveness at reducing children’s

blood lead levels.

Behavioral studies are needed to understand risk perception—Although studies have

been done to understand risk perception regarding a multitude of other diseases (13), no

systematic study has been done of caregivers of children with elevated blood lead levels to

understand their perception of risk regarding lead and how this perception affects their uptake of

interventions. In order to develop more effective educational programs and to increase uptake of

abatement strategies, it is necessary to understand how caregivers view lead and its effects on

health.

Conclusions

The evidence for residential lead abatement strategies is mixed with some studies

showing high efficacy and some showing no change in children’s blood lead levels post-

intervention. On the basis of the current review it is not possible to say with certainty which

methods of lead abatement are effective at reducing children’s blood lead levels. More research

with good study designs needs to be undertaken before interventions with proven effectiveness

23


can be identified. It is essential that this research be done in order to prevent the life long

damaging affects of lead poisoning in children.

24


References

1. Sutton P, Athansoulis M, Flessel P, Guirguis G, Haan M, Schlag R, et al. (1995) Lead levels in the household environment of children in three high-risk communities in California. Environmental Research, 68:45-57.

2. Pirkle JL, Brody DJ, Gunter EW, et al. (1994) The decline in blood lead levels in the United States: the National Health and Nutrition Examination Surveys (NHANES). JAMA, 272:284-291.

3. Lanphear B, Weitzman M, Winter N, Eberly S, Yakir B, Tanner M, et al. (1996) Lead-contaminated house dust and urban children’s blood lead levels. American Journal of Public Health, 86(10):1416-1421.

4. Stedling D, Dunlap C, Flegal R (2000) New isotopic evidence for chronic lead contamination in the San Francisco Bay estuary system: Implications for the persistence of past industrial lead emissions in the biosphere. Proc Natl Acad Sci, 97(21): 11181-11186.

5. Lanphear B, Succop P, Roda S, Henningsen G (2003) The effect of soil abatement on blood lead levels in children living near a former smelting and milling operation. Public Health Reports, 118: 83-91.

6. Murgueytio A, Evans G (1996) Prevalence of childhood lead poisoning in a lead mining area. Journal of Environmental Health, 58(10): 50-57.

7. Kaste J, Friedland A, Sturup S (2003) Using stable and radioactive isotopes to trace atmospherically deposited PB in Montane forest soils. Environ. Sci. Technol. 37(16):3560-3567.

8. Warner-Smith M (1999) Satisfaction with the process of lead remediation in an urban Australian community. Australian and New Zealand Journal of Public Health, 23(6):617-621.

9. Davis J, Elias R, Grant L (1993) Current issues in human lead exposure and regulation of lead. Neurotoxicology, 14(2-3):15-28.

10. Brody DJ, Pirkle JL, Kramer RA, Flegal KM, Matte TD, Gunter EW, et al.(1994) Blood lead levels in the US population. Phase I of the Third National Health and Nutrition Examination Survey (NHANES III, 1988 to 1991). JAMA, 272(4):277-83.

11. Mushak P. (1992) Defining lead as the premiere environmental health issue for children in America: criteria and their quantitative application. Environmental Research, 59:281-309.

12. U.S. Environmental Protection Agency. National Primary Drinking Water Regulations: Technical Factsheet on Lead. Available at: www.epa.gov/safewater/dwh/t-ioc/lead.html. Accessed on April 11, 2004.

13. President’s Task Force on Environmental Health Risks and Safety Risks to Children. “Eliminating Childhood Lead Poisoning: A Federal Strategy Targeting Lead Paint Hazards”. February 2000.

14. U.S. Department of Health and Human Services. “Analysis Paper: Impact of Lead-Contaminated Soil on Public Health”. Available at: www.atsdr.cdc.gov/cxlead.html. Accessed on February 14, 2004.

25


15. Farfel M, Orlova A, Lees P, Rohde C, Ashley P, Chisolm J. (2003) A study of urban housing demolitions as sources of lead in ambient dust: demolition practices and exterior dust fall. Environmental Health Perspectives, 111(9):1228-1234.

16. Pollak J. (2002) The lead-based paint abatement repair and maintenance study in Baltimore: historic framework and study design. Journal of Health Care, Law, and Policy, 6(1):89-108.

17. Haynes E, Lanphear B, Tohn E, Farr N, Rhoads G. (2002) The effect of interior lead hazard controls on children’s blood lead concentrations: a systematic evaluation. Environmental Health Perspectives, 110(1):103-107.

18. Mielke H, Berry K, Mielke P, Powell E, Gonzales C. (in press) Multiple metal accumulation as a factor in learning achievement within various New Orleans elementary school communities. Environmental Research.

19. Gasana J, Chamorro A. (2002) Environmental lead contamination in Miami in inner-city area. Journal of Exposure Analysis and Environmental Epidemiology, 12: 265-272.

20. Bradman A, Eskenzai B, Sutton P, Athanasoulis M, Goldman L. (2001) Iron deficiency associated with higher blood lead in children living in contaminated environments. Environmental Health Perspectives, 109(10):1079-1084.

21. Elhelu M, Caldwell D. (1995) Lead in inner city soil and its possible contribution to children’s blood lead. Archives of Environmental Health, 50(2):165-170.

22. Roberts J, Hulsey T, Curtis G, Routt R. (2003) Using geographic information systems to assess risk for elevated blood lead levels in children. Public Health Reports, 118: 221-229.

23. Powell D, Stewart V. (2001) Children: the unwitting target of environmental injustices. Pediatric Clinics of North America, 48(5):30-44.

24. Lanphear B, Matte T, Rogers J, Clickner R, Dietz B, Bornschein R, et al. (1998) The contribution of lead-contaminated house dust and residential soil to children’s blood lead levels: a pooled analysis of 12 epidemiologic studies. Environmental Research, 79: 51-68.

25. Sheldrake S, Stifelman M (2003) A case study of lead contamination cleanup effectiveness at Bunker Hill. The Science of the Total Environment, 303: 105-123.

26. Norman E, Bordley C, Hertz-Picciotto I, Newton D (1994) Rural-urban blood lead differences in North Carolina children. Pediatrics, 94(1):59-64.

27. Aschengrau A, Beiser A, Bellinger D, Copenhafer D, Weitzman M (1994) The impact of soil lead abatement on urban children’s blood lead levels: phase II results from the Boston lead-in-soil demonstration project. Environmental Research, 67:125-148.

28. Aschengrau A, Beiser A, Bellinger D, Copenhafer D, Weitzman M (1997) Residential lead-based-paint hazard remediation and soil lead abatement: their impact among children with mildly elevated blood lead levels. American Journal of Public Health, 87(10):1698-1702.

26


29. Charney E, Kessler B, Farfel M, Jackson D (1983) A controlled trial of the effect of dust-control measures on blood lead levels. New England Journal of Medicine, 309(18):1089-1093.

30. Dixon S, Tohn E, Rupp R, Clark C (1999) Achieving dust lead clearance standards after lead hazard control projects: an evaluation of the HUD-recommended cleaning procedure and an abbreviated alternative. Applied Occupational and Environmental Hygiene, 14: 339-344.

31. Amitai Y, Brown M, Graef J, Cosgrove E (1991) Residential deleading: effects on the blood lead levels of lead-poisoned children. Pediatrics, 88(5):893-897.

32. Ettinger A, Bornschein R, Farfel M, Campbell C, Ragan N, Rhoads G, et al. (2002) Assessment of cleaning to control lead dust in homes of children with moderate lead poisoning: treatment of lead-exposed children trial. Environmental Health Perspectives, 110(12):A773-A779.

33. Farfel M, Chisolm M (1991) An evaluation of experimental practices for abatement of residential lead-based paint: report on a pilot project. Environmental Research, 55: 199-212.

34. Farfel M, Chisolm M (1990) Health and environmental outcomes of traditional and modified practices for abatement of residential lead-based paint. American Journal of Public Health, 80(10):1240-1245.

35. Lanphear B, Winter N, Apetz L, Eberly S, Weitzman M (1996) A randomized trial of the effect of dust controls on children’s blood lead levels. Pediatrics, 98(1):35-40.

36. Lanphear B, Howard C, Eberly S, Auinger P, Kolassa J, Weitzman M (1999) Primary prevention of childhood lead exposure: a randomized trial of dust control. Pediatrics, 103(4):772-777.

37. Lanphear B, Eberly S, Howard C. (2000) Long-term effect of dust control on blood lead concentrations. Pediatrics, 106(4):223-227.

38. Lioy PJ, Yiin LM, Adgate J, Weisel C, Rhoads GG (1998) The effectiveness of a home cleaning intervention strategy in reducing potential dust and lead exposures. J Expo Anal Environ Epidemiol, 8(1):17-35.

39. Rhoads, G. Ettinger A, Weisel C, Buckley T, Goldman K, Agate J, et al. (1999). The Effect of Dust Lead Control on Blood Lead in Toddlers: A Randomized Trial. Pediatrics, 103(3): 551-555.

40. Schultz B, Pawel D, Murphy A. (1999) A retrospective examination of in-home educational visits to reduce childhood lead levels. Environmental Research, 80; 364-368.

41. Staes C, Matte T, Copley C, Flanders D, Binder S. (1994) Retrospective study of the impact of lead-based paint hazard remediation on children’s blood lead levels in St. Louis, Missouri. American Journal of Epidemiology, 139(10):1016-1026.

42. Yiin, LM Rhoads G, Rich D, Zhang J, Bai Z, Adgate J, et al. (2002) Comparison of techniques to reduce residential lead dust on carpet and upholstery: the New Jersey assessment of cleaning techniques trial. Environmental Health Perspectives, 110(12): 1233-1237.

27


43. Yiin, LM., Lioy, PJ., and Rhoads, GG.,(2003): Impact of Home Carpets on Children Lead Intervention Study. Environmental Research, 92(2): 161-165.

44. Farrell K, Brophy M, Chisolm J, Rohde C, Strauss W (1998): Soil lead abatement and children’s blood lead levels in an urban setting. American Journal of Public Health, 88(12): 1837-1839.

45. Weitzman M, Aschengrau A, Bellinger D, Jones R, Hamlin J, Beiser A. (1993). Lead-Contaminated Soil Abatement and Urban Children’s Blood Lead Levels. Journal of the American Medical Association, 269(13): 1647-54.

46. Aschengrau A, Hardy S, Mackey P, Pultinas D (1998). The Impact of Low Technology Lead Hazard Reduction Activities among Children with Mildly Elevated Blood Lead levels. Environmental Research, section A 79: 41-50.

47. Lange J, Bruce K, Johnson B, Phillips M, Smith D, Weidenboemer K (1998) A survey of lead-based paint abatement projects performed in public buildings in Erie and Crawford Counties, Pennsylvania, during the time period 1995-1997. Regulatory Toxicology and Pharmacology, 28:73-78.

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Appendix A. Conceptual Framework Illustrating Factors Associated with Children’s Elevated Blood Levels and the Interventions Used to Mitigate the Problem

29

Demographics:--Race/Ethnicity--Socioeconomic Status--Child’s Age--Parent’s Income--Parent’s Education Level--Place of Residence

Housing:--pre-1950 housing--pre-1978 paints

Soil Contamination:--Lead in soil/lawns--Lead in paint chips--Car emissions

Drinking Water:--Lead in pipes/solder

Elevated Blood Lead Levels in Children

Health Effects:--Low cognitive function--Neurobehavioral deficit--Impaired growth--Hearing problems--Severe stomach cramps--Impaired nerve function

Monitoring of Tap Water for Lead

Soil Abatement

Dust and Paint Abatement

Chelation

Legend:Factors leading to lead exposure

Interventions to mitigate lead exposure


Appendix B. Table Reviewing the Evidence for the Effectiveness of Residential Lead Abatement StrategiesCitation, Year Purpose of Article Target

PopulationSetting Methods Results

Interior Dust/Paint Abatement InterventionsAmitai, Y, et al. (1991) Residential deleading: effects on the blood lead levels of lead-poisoned children. Pediatrics, 88(5):893-897. (31)

To evaluate whether the blood lead levels of children with chronic lead poisoning actually increase or decrease during deleading of their homes.

Children younger than 6 years of age who had a confirmatory blood lead level of >25 μg/dL.

Boston, MA The authors studied the change in blood lead levels before, during, and immediately after deleading of homes in relation to methods of deleading, and the subjects’ age at the initiation of deleading.

Blood lead levels during deleading were significant higher than pre-deleading levels (42.1 μg/dL vs. 36.4 μg/dL, (p<0.001). Post-deleading blood lead levels were significantly lower than mid-deleading (33.5 μg/dL vs. 42.1 μg/dL, p<0.001) and pre deleading levels (33.5 μg/dL vs. 36.4 μg/dL, p<0.02). The amount of increase in blood lead levels during deleading varied substantially by type of deleading method used.

Aschengrau et al., (1998). The Impact of Low Technology Lead Hazard Reduction Activities among Children with Mildly Elevated Blood Lead levels. Environmental Research, section A 79: 41-50. (46)

The study was conducted to determine the impact of low technology lead hazard reduction among children with mildly elevated blood lead levels.

Children who resided in the city of Boston and who were less than 4 years of age with lead blood levels from 11 to 24μg/dL were selected for the study.

Boston, MA The study design followed a stratification method. Participants were stratified according to the severity of their household lead hazards. Children with severe lead hazard were automatically assigned to an intervention group and those with perceived less lead hazard were assigned to the control group. The one time intervention consisted

The lead reduction activities were associated with a modest decline of blood lead levels among children with severe hazards. The decline ranged from -1.1 to -1.6μg/dL. A reduction of window well dust lead loading levels was also observed.

30


of 1) high-efficiency vacuuming of all window wells, window sills, and floor sills; 2) washing window wells and sills with tri-sodium phosphate; 3) repainting window well and sill with primer to seal chipped/flaking paint; 4) repairing holes in walls.

Ettinger at el., (2002). Assessment of Cleaning to Control Lead Dust in Homes of Children with Moderate Lead Poisoning: Treatment of Lead Exposed Children Trial. Environmental health Perspectives, 110(12): 773-779. (32)

The study quantified the effectiveness of professional cleaning in reducing blood lead levels of children.

Children between the ages of 12 to 33 months and have blood lead level between 20 to 44μg/dL. (n = 384).

Baltimore, Cincinnati, Newark, and Philadelphia.

Pre and post study design was used to measure the effectiveness of dust abatement by professional cleaning of homes in reducing lead exposure for children undergoing treatment for lead exposure.

Following cleaning, floor dust lead loadings were reduced on average 32% for floor samples (p<0.0001), 66% for windowsills (p<0.0001) and 93% for window wells (p<0.0001) comparing pre and post levels. Despite these substantial reductions in dust lead loadings, a single professional cleaning did not reduce lead loadings in dust samples to levels below current federal standards for lead in residential dust.

Farfel, D., and Chilsom, J., (1991). An Evaluation of Experimental Practices for Abatement of Residential Lead Based Paint: Report on a Pilot Project. Environmental Research, 55:199-212.

This study evaluated experimental practices for abating lead based paint in six dwelling.

Children living in structurally sound but poorly maintained housing in an inner city neighborhood

Baltimore, Maryland

Experimental abatements involved (i) treatment of lead painted surfaces above and below 4fts from the floor, including interior and exterior

The experimental abatements resulted in a significant reductions in house dust levels (PbD) which persisted during 6-9months of follow up. The geometric mean PbD at floors, window sills, and window

31


(33) components of windows. (ii) sealing or covering of wooden floors. (iii) procedure for containment of dust during abatement. (iv) final clean up using a high efficiency particle air (HEPA)vacuum.

wells were respectively 5.6, 49.6 and 316.7mg/m2 at preabatement, and respectively 0.6, 4.4, and 10.8mg/m2at 6-9 months.

Farfel, D., and Chisolm, J., (1990). Health and Environmental Outcomes of Traditional and Modified Practices of Abatement of Residential Lead Based Paint. American Journal of Public Health, 80(10):1240-1245.(34)

An evaluation of traditional and modified practices for abating lead based paint in homes of children with blood lead concentration >1.4μmol/L.

Children between the ages of 9 to 72 months who spent 75% of his/her time living in the abated dwelling.

Baltimore, Maryland

Measurements of lead in interior surface dust and children’s blood were made pre-abatement, post abatement and six months post abatement.

By six months, neither form of abatement resulted in long term reductions of Blood lead (PdB) or house dust lead levels. Lead dust levels on floors went from 2.7 mg/m2 pre-abatement to 3.4 mg/m2 at 6-months post-abatement using the traditional method, whereas the equivalent numbers for the modified method were 3.1 mg/m2 to 3.4 mg/m2. Similarly, window wells went from 14.4 mg/m2 to 16.6 mg/m2 using the traditional method and 19.4 mg/m2 to 17.6 mg/m2 using the modified method. Neither was a significant change.

Lanphear et al (1996): A Randomized Trial of the Effect of Dust on Children’s Blood Lead Levels. Pediatrics, 98(1): 35-40.(35)

This study was conducted to determine whether dust control, as performed by families, had an effect on children’s blood lead

Young children between the ages of 12 and 31 months. (n =104).

Community based trial in Rochester, New York

Randomized, control trial. Families and children were randomized to two groups. Families in the intervention group received cleaning

There was no significant difference in the change of children’s blood lead levels or dust lead levels by treatment group. The median change in blood lead levels among children in the intervention

32


levels and dust lead levels in children’s homes.

supplies, information about cleaning areas that are often contaminated with lead, and a cleaning demonstration. The families in the control group received only a brochure about lead poisoning prevention.

group was -0.05 μg/dL compared with -0.60 μg/dL among those in the control group.

Lanphear et al (1999): Primary prevention of childhood lead exposure: A randomized trial of dust control. Pediatrics, 103(4):772-777. (36)

To determine the effectiveness of dust control in preventing children’s exposure to lead, as measured by blood lead levels.

Children between the ages of 6 to 30 months.

Rochester, New York

Children and their families were randomly assigned to an intervention group, which received cleaning equipment and up to eight visits by a dust control advisor or a control group.

At 6 months the blood lead level of children in the intervention group was 2.8 μg/dL compared to 2.9 μg/dL in the control group (p=0.51). At 12, 18, and 24 months the numbers were as follows: 5.5 μg/dL vs. 5.9 μg/dL (p=0.40), 5.9 μg/dL vs. 6.2 μg/dL (p=0.58), and 7.3 μg/dL vs. 7.8 μg/dL (p=0.47) comparing the intervention to the control group. Therefore, dust control as performed by families and in the absence of lead hazard controls to reduce ongoing contamination from lead based paint is not effective in the primary prevention of child lead exposure.

Lanphear, B (2000) Long-term effect of dust control on blood lead concentrations. Pediatrics, 106(4): 1-4. (37)

To determine the long term effectiveness of dust control in preventing children’s exposure to lead, as measured by blood

Children between the ages of 6 to 30 months.

Rochester, New York

Children and their families were randomly assigned to an intervention group, which received cleaning equipment

Baseline geometric mean blood lead concentrations were 2.8 μg/dL. At 48 months of age, the geometric mean blood lead level was 5.9 μg/dL for the intervention group and 6.1

33


lead levels. and up to eight visits by a dust control advisor or a control group.

μg/dL for the control group. No significant difference in the mean blood level at the 48-month follow-up was observed between the intervention and control group. The percent of children with a 48-month blood lead level ≥10 μg/dL was 19% for the intervention group and 19% for the control group.

Lioy PJ, et al. (1998) The effectiveness of a home cleaning intervention strategy in reducing potential dust and lead exposures. J Expo Anal Environ Epidemiol, 8(1):17-35. (38)

To examine the efficacy of a cleaning protocol at reducing the lead loadings of dust in the homes of children with moderate lead poisoning.

Children under the age of 6 years with blood lead levels between 10-20 μg/dL.

Hudson County, New Jersey

Homes of children with moderate lead poisoning were randomized to receive either a standardized lead intervention program or an accident intervention program (an intervention to reduce accidents in the home). Lead loadings in dust were then compared pre- and post-intervention as well as comparing the intervention and comparison group.

There was a statistically significant decline (p<0.05) in the lead loadings in dust measured pre- and post-intervention. In addition there were substantial reductions in lead levels in dust comparing the lead intervention homes and the accident intervention comparison homes. There was a 75% and 50% reduction in the amount of lead observed on window sills and bedroom floors in the homes which participated in the lead intervention compared to the accident intervention.

Rhoads, G. et al, (1999). The Effect of Dust Lead Control on Blood Lead in Toddlers: A Randomized Trial. Pediatrics, 103(3): 551-555.(39)

The study was conducted to evaluate an intervention consisting of maternal education and household dust control measures on blood

Young children between the ages of 6 and 36 months. (n = 113).

Jersey City, New Jersey

Children were randomized into two groups, a study group and control group. The study group intervention was composed of maternal

Blood lead level fell 17% in the intervention group and did not change among controls. Household dust and dust lead measures fell significantly (reduced by 50%) in the intervention group.

34


lead levels in young children at risk of excessive lead exposure.

education and biweekly assistance with household cleaning.

Schultz B, et al. (1999) A retrospective examination of in-home educational visits to reduce childhood lead levels. Environmental Research, 80; 364-368.(40)

To examine the efficacy of a one hour educational visit in reducing the blood lead levels of children with moderate levels of lead poisoning.

Children under 6 years of age who had elevated blood lead levels between 20 and 24 μg/dL.

Milwaukee, Wisconsin

Children with elevated blood lead levels between 20 and 24 μg/dL were found through a retrospective examination of Milwaukee Health Department records. Children were then randomized to receive an in-home educational visit by a health professional or to be in a control group. In-home educational visits lasted about an hour and discussed dust clean-up practices to reduce lead exposure.

After the intervention, the average observed blood lead level declined by 4.2 μg/dL (-21%) for the intervention group compared to a decline of 1.2 μg/dL (-6%, p<0.001) for the reference group. The decline in blood levels was 3.1 μg/dL greater (15% ) in the families who received education in the homes versus those that did not(p =0.001).

Staes C, et al. (1994) Retrospective study of the impact of lead-based paint hazard remediation on children’s blood lead levels in St. Louis, Missouri. American Journal of Epidemiology, 139(10):1016-1026.(41)

To compare changes in the blood lead levels of children whose dwellings did and did not undergo remediation for lead-based paint hazard

Children younger than age 6 years who had an initial diagnosis of a venous blood lead level of 25 μg/dL or higher and who had not yet received treatment with a chelating agent.

St. Louis, Missouri

Using records from the St. Louis City Health Department, the authors identified children with blood lead levels ≥25 μg/dL. Using t tests and multiple linear regression methods, they then compared the relationship among

The geometric mean blood lead level decreased 23% among children living in remediated dwellings and 12% among children in non-remediated dwellings (p=0.07). The effect of remediation was greater among children whose blood lead levels at diagnosis were ≥35 μg/dL (-22%) than among those whose blood lead

35


the change in blood lead levels and the remediation status of the child’s dwelling at follow-up.

levels at diagnosis were between 25 and 34 μg/dL (1%).

Yiin, LM et al. (2002) Comparison of techniques to reduce residential lead dust on carpet and upholstery: the New Jersey assessment of cleaning techniques trial. Environmental Health Perspectives, 110(12): 1233-1237.(42)

To determine whether a conventional (non-HEPA) vacuum cleaner could achieve cleaning results comparable with those of a HEPA vacuum cleaner.

Children under 6 years of age with a blood lead level ≥20 μg/dL.

New Jersey Homes where a child with a blood lead level ≥20 μg/dL were randomly assigned to receive cleaning of carpets and upholstery with either a high-efficiency particulate air (HEPA) filtered vacuum or a regular canister vacuum cleaner. Lead levels of dust wipes were then compared across interventions.

The vacuum sampling data showed that the HEPA and non-HEPA vacuum cleaners resulted in 54.7% (p=0.006) and 36.4% (p=0.02) reductions in lead loading on soiled carpets comparing the pre- and post-intervention levels. The overall difference in lead loading was not statistically significant (p=0.293). Neither type of cleaner was effective at reducing lead levels on carpets and upholstery below federal guidelines.

Yiin, LM., Lioy, PJ., and Rhoads, GG.,(2003): Impact of Home Carpets on Children Lead Intervention Study. Environmental Research, 92(2): 161-165.(43)

The study examined the effectiveness of cleaning carpets as an intervention to reduce blood lead levels in children.

Children less than 6 years of age

New Jersey Children were classified into two groups, the carpeted house group and the uncarpeted house group. All eligible houses were classified as carpeted and uncarpeted depending on the number of carpeted rooms. Both types of houses were then cleaned according to a high-efficiency particulate air filtered vacuum

The results of the study showed a significant reduction of children blood lead levels for the uncarpeted home (p =0.004) and no significant change was found for the carpeted homes (p =0.0566).

36


protocol.Soil Abatement InterventionsFarrell et al (1998): Soil lead abatement and children’s blood lead levels in an urban setting. American Journal of Public Health, 88(12): 1837-1839.(44)

The effect of abating soil lead was assessed among Baltimore children.

Children from 6 months to 6 years of age.

Baltimore, Maryland

Two neighborhoods were randomly assigned to study and control conditions. In the study area contaminated soil was replaced with clean soil.

One year post-abatement children’s blood levels were 9.7 μg/dL in the study group (compared to 9.6 μg/dL at baseline) and 8.4 μg/dL in the control group (compared to 9.1 μg/dL at baseline). The change in blood lead levels comparing the intervention and control group one-year post abatement was not significant. Therefore, soil abatement did not lower children’s blood lead levels.

Lanphear, et al. (2003) The Effect of Soil Abatement on Blood Lead Levels in Children Living Near a Former Smelting and Milling Operation. Public Health Report, 118:83-91(5)

An evaluation of the effect of soil abatement on children’s blood lead concentrations and on environmental levels of lead and arsenic.

Children between the ages of 6 and 72 month living in homes with average soil lead concentration >500ppm.

Midvale, Utah Two cross –sectional survey were performed. The first(1989) was a random sample of 6 to 72 month children(n =112) and the second(1998) included all 6 to 72 month old children (n = 215)

The results of the study showed a significant decline in lead and arsenic in soil and interior dust in homes that underwent soil abatement (p<0.05). The blood lead levels of children ages 6 to 72 month who lived in soil abated housing declined 42.8% faster that who children lived in unabated housing(p = 0.14). In children 6 to 36 months, the decline was 45.4% faster (p = 0.03). Soil abatement was associated with a significant decline in children’s blood lead and indoor environmental levels of lead and arsenic.

Weitzman et al., (1993). Lead-Contaminated Soil Abatement

The study tested the hypothesis that a

Children of less than 4 years of

Boston. (Urban areas

Randomized control trial of the effects of

The results of the study shows that abatement of lead-

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and Urban Children’s Blood Lead Levels. Journal of the American Medical Association, 269(13): 1647-54.(45)

reduction of 1000ppm or more of lead in soil accessible to children would result in a decrease of at least 0.14mμmol/L (3μg/dL) in blood lead levels.

age with venous blood lead levels of 7 to 24μg/dL. (n = 152)

with a high incidence of children lead poisoning and high soil lead levels).

lead contaminated soil abatement on blood lead levels of children followed up for approximately 1 year after the intervention. Children were randomized to one of three groups, the study group, whose homes received soil and interior dust abatement and loose paints removal; comparison group A whose homes received interior dust abatement and loose paint removal; and comparison group B, whose homes received only interior loose paint removal.

contaminated soil around homes results in a modest decline in blood lead levels. The mean blood lead level of the study group declined 1.53 μg/dL more than that of group A and 1.92 μg/dL more than that of group B. The magnitude of the decline independently associated with soil abatement ranged from 0.8 to 1.6 μg/dL after controlling for potential confounders.

Interventions Targeting Multiple PathwaysAschengrau, et al. (1994) The impact of soil lead abatement on urban children’s blood lead levels: phase II results from the Boston lead-in-soil demonstration project. Environmental Research, 67:125-148.(27)

To study the impact of an urban soil lead abatement project on children’s blood lead levels.

Children who lived in areas with a high incidence of lead poisoning, were under 4 years, and had a finger stick blood lead level from 10 to 20 μg/dL.

Boston, MA Soil abatement was conducted at homes that had average surface soil lead levels of at least 1500 ppm. The soil abatement consisted of removing 6 in. of top soil from the entire yard and replacing it with 8 in. of clean soil and ground cover. The

A soil lead reduction of 2060 ppm is independently associated with a 2.25 to 2.70 μg/dL decline in children’s blood lead levels. Several yards showed evidence of recontamination with lead both at 6-10 and 8-22 months after soil abatement; however, recontamination levels were fairly low (<300 ppm).

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authors then compared children’s blood lead levels before and after the intervention.

Aschengrau et al., (1997). Residential Lead-Based-Paint Hazard Remediation and Soil Lead Abatement: Their Impact among Children with Mildly Elevated Blood Lead levels. American Journal of Public Health, 87(10): 1698-1702.(28)

The study describes the impact of residential lead based paint hazard remediations and soil abatement on children with mildly elevated blood lead levels.

Children with blood lead levels between 7 and 24μg/dL and who were less than 4 years of age were enrolled in the study. (n = 152).

Boston, MA Children were randomized to two groups (Group 1—soil abatement, interior dust abatement; and interior loose-paint stabilization; Group 2—Interior loose paint stabilization only). Changes in blood lead levels were observed following paint hazard remediation alone and in combination with soil abatement.

Lead-based paint remediation alone was associated with statistically significant blood lead increase of 6.5 μg/dL over the subsequent 9 months of follow-up but with an increase of only 0.9 μg/dL when combined with soil abatement. Neither intervention reduced blood lead levels in children.

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