EHS 507

Food Exposures: Fruits and Vegetables Fruits and vegetables may become

contaminated by multiple pathways – Purposeful spraying or soil treatment with

pesticides, fertilizers– Ambient air pollutant deposition, or absorption

by, plants– Contaminants dissolved in rainfall or irrigation

water which contacts plants– Plant root absorption of contaminants in soil and

in groundwater

EHS 507

EHS 507

Exposure to pesticides can involve complex processes and multiple pathways.

Exposure to pesticides can involve complex processes and multiple pathways.

EHS 507

Food Exposures: Dairy & Meats Basic issues are similar to those for

fruits and vegetables Exposure pathways and modeling

even more complex than for fruits and vegetables– Must consider

• Contamination of animal food sources (same host of issues as for human food sources)

• Contamination of drinking water sources

• Uptake, metabolism, distribution, and excretion in the animal

• Pre-consumer processing of foods (e.g., pasteurization of milk)

EHS 507

Food Exposures: Fish and Shellfish

Fish and shellfish are of substantial concern as contaminated food sources:– Both heavy metals (e.g., mercury)

and lipophilic substances (e.g., DDT metabolites, polychlorinated biphenyls (PCBs)) may bioconcentrate in aquatic food chain• Contaminants can be present both

in surface water and retained for very long periods in sediments as continuing “reservoir”

– Subsistence and, to lesser extent, sports fisherman may consume many times average of overall population

EHS 507

Food Exposures: Breast Milk

Important because: – Usually only source of nutrition for the

infant and large caloric intake as compared to body weight

– Infants likely to be especially sensitive to adverse health effects of contaminants

– Lipophilic substances (dioxins, DDT metabolites, etc.) will concentrate in breast milk

EHS 507

Soil and house dust ingestion: children

Children expected to be at greatest risk for intake of contaminants through soil and house dust– Increased susceptibility to toxins– Frequent mouthing of objects and hands (> 80 %

in those <1 year)– Play activities– Wide range of estimates of average daily ingestion

• Use of 100 mg/d recommended as a conservative estimate of soil ingestion in toddlers (ages 2-4)

– Pica = deliberate ingestion of non-nutritive substances

• Rare, but may be associated with ingestion orders of magnitude higher

EHS 507

Soil and House Dust Ingestion: children Ingestion of substances while indoors

– Ingestion of lead paints (lead salts have sweetish taste) a well-recognized and studied risk• Use of lead for interior paints banned for many

years, but peeling layers of paint in older households still may present a risk

– House dust may be a particular risk because of residual pesticides as well as lead

EHS 507

Ocular Exposures

Major concern here is with direct local effects

Strong acids, strong bases, oxidants, etc. of particular concern

Potential for irreversible damage and, in very severe exposures, loss of vision

Systemic absorption rarely a significant issue

EHS 507

Parenteral Exposures

Main concern is in occupational settings – injection of infectious agents under the

skin– exposure to “sharps” in healthcare

settings: hypodermic needles, scalpels, etc.

– Injection and/or exposure through cuts/abraded skin may also occur in other settings: laundering of bedding, fireman/policemen/emergency responders, etc.

– Major agents of risk in the U.S. : HIV, Hepatitis B, Hepatitis C

– Chemical properties of injected materials usually of little concern because typical volumes involved are minute