childrens health pesticide exposure
TRANSCRIPT
Challenges in Protecting Children from Pesticide Exposure
Michael J. DiBartolomeis, PhD, DABT
California Department of Public Health
January 20, 2015
Chemical Pesticides
• Chemicals used to kill, repel, control, or prevent pests • Classes: insecticides, fungicides, herbicides, antimicrobials
and disinfectants, rodenticides • Designed to be used individually or in combination • Pesticide formulation = active ingredient(s) + other
(“inert”) ingredients • Most are synthetic agents new to humans and the
environment Nearly 900 “active ingredients” in about 1,400 registered
products 83 restricted use active ingredients in 300 products 288 “inert” ingredients allowed
Pesticides Contribute to Disease
• Asthma and other respiratory problems
• Skin problems
• Birth Defects
• Cancer
• Loss of ability to learn (lower IQ)
• Liver, kidney, or other organ disease
• System failure (e.g., immune, reproductive, endocrine)
• Nervous system disorders
• General poor health (“morbidity”)
• Premature death (“mortality”)
Regulating Pesticide Use and Safety
• Federal laws require pesticides to be tested for toxicity before they are marketed; safety testing is only done for individual pesticides
• Laws and rules also require safety measures to be taken to protect workers and nearby residents
• Label = law
• Registration decisions must consider economics
• The laws and the rules are not always enforced
Regulating Pesticide Use and Safety
Toxicology I.
Data Review & Risk Assessment
Exposure
Integrated Pest Management
II.
Management Options
Regulation
Investigation III.
Implementation & Enforcement
Reporting
Acute Toxicity Testing
• Oral toxicity study LD50 (rat)
• Dermal toxicity LD50 (rat)
• Inhalation toxicity LC50 (rat)
• Primary eye irritation (rabbit)
• Primary dermal irritation (rabbit)
• Dermal sensitization (Guinea pig)
• Delayed neurotoxicity (hen)
Subchronic Toxicity Testing
• Two feeding studies (rat, dog)
• 21-Day dermal
• 90-Day dermal
• Inhalation (rat)
• Two neurotoxicity studies (rat, hen)
Chronic Toxicity Testing
• Two feeding studies for animal’s lifetime or two years (rat, dog)
• Two cancer bioassays (mouse, rat) for animal’s lifetime or two years
• Two birth defect studies
• Reproduction study spanning two generations
• Developmental neurotoxicity study
Genetic Toxicity Testing
• Gene mutation
• Structural chromosome damage
• Other genetic toxicity
• Requires at least three studies, one study from each of the three different categories
• Live animal studies, single cell organisms, cell tissue or cellular components such as DNA, or cell cultures
Exposure to Chemicals
• Contact has to be made with a chemical: no exposure = no toxicity
• Toxic chemicals generally produce the greatest effect and most rapid response when they get into the bloodstream
Exposure Data Sources
• Environmental monitoring (air, water, soil)
• Food residue testing
• Biomonitoring
• Personal monitors
• Illness reports & investigations
Exposure Dose and Duration
• The dose is the amount of a chemical that is needed to cause an effect
• The length of time that a person is in contact with a chemical matters
• Human exposures are often described in relation to a sensitive time period
Children’s Exposure to Pesticides
Sources Airborne (drift, ambient)
Carpet, floor
Clothing
Drinking water
Food
Grass, soil, other surfaces
Household products
Parents or other adults
Surface water
Locations Home
Irrigation ditches
Nearby fields
Parks
School
Streams, rivers with agricultural runoff
Why Are Children More Susceptible to Pesticide Toxicity than Adults?
• Greater exposure pound-for-pound
• Eat and drink more; inhale relatively more air
• Decreased ability to detoxify many chemicals
• Less well-developed immune systems
• Undergo rapid growth, during which cells are more vulnerable
• Exposure to toxic chemicals early in life
• Heightened biological vulnerability (e.g., thalidomide, DES, fetal alcohol syndrome)
Principal Causes of Children’s Illness in the US
• Asthma
• Cancer
• Birth defects
• Neurodevelopmental disorders
• Obesity and diabetes
Organophosphate Pesticides: Neurodevelopmental Disorders
• High-dose exposure can cause acute poisoning
• Exposure during pregnancy to lower levels may cause:
Shorter duration of pregnancy
Small head circumference, low birth weight
Developmental delays
Poorer neonatal reflexes
Lower IQ and poorer cognitive functioning in children
Increased risk of attention problems in children
Food Quality Protection Act of 1996
• Pre- and postnatal toxicity
• Completeness of data (exposure and toxicity to infants and children)
• Developmental neurotoxicity
• Endocrine disruption
• “Safety” factor
• Risk assessment for pesticides with a common mechanism of toxicity
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Risk
• Estimate of the probability of harm • For a chemical, risk is the product of exposure
(dose) times toxicity • Requires defining an acceptable level of harm • May be voluntary or involuntary • Existing vs. future (potential) risks • Individual vs. population • Single or mixtures (additive, antagonistic, or
synergistic)
Shortcomings of Risk Assessment
• Not transparent: includes analysts’ judgments and values
• Disempowering (undemocratic)
• Leads to regulatory delays (“paralysis by analysis”)
• Allows some amount of pollution to continue
• Methodology is lacking; limited by uncertainty and data gaps
• Often neglects qualitative aspects of pollution
• Little public participation
• Subpopulations or individuals may be more vulnerable,
sensitive, or susceptible than “average”
• Limited capacity to identify and prevent impacts on public
health and the environment from emerging threats
Other Environmental Decision-Making Models
• Regulation model: risk/benefit
• Public health model: surveillance, intervention, education
• Exposure based: body burden (or burden on ecosystem)
• Public involvement: democratic process
• Precautionary model: based on prevention