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 to Chemicals

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

Mahalo