Transcript EHS507.1.29.04.ExpRoutes.m10

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
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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)
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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
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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
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• Rare, but may be associated with ingestion orders of
magnitude higher
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
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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
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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
EHS 507