ChlorpyrifosENV H 572

Hilary Zetlen

Chlorpyrifos

Organophosphate pesticide

Marketed by Dow Chemical since 1965

Domestic and agricultural uses

Prevalent Use

Broad spectrum of applications Treatment of crops, lawns, building materials.

10 million lbs. applied each year Majority applied to corn (approx. 5.5 millions lbs. annually)

Commonly used for vegetables, tree fruit in Washington state

Home use canceled in 2000 Previously most commonly used residential pesticide Limited to tightly controlled childproof mechanisms

Annual use, Lbs. (% crop treated)

Regulatory Standing

CERCLA Reportable quantity of release = 1 lb.

Clean Water Act Allowable level = 20 ug/ L

FDA 0.05-15 ppm on food

FIFRA / EPA Currently undergoing registration review NRDC / PAN requesting revocation of registration Final decision in 2015

Stakeholders

Dow Chemical Corp. and pesticide manufacturers

Agribusiness, small farmers, and agricultural communities

Consumers

Government agencies

The environment

Hazard Identification

What is it?

White crystalline solid

Synthesized from 3-methylpyridine

Hydrophobic; often applied dry or in an oil/solvent suspension

Frequently marketed as Dursban/Lorsban

Organophosphate Pesticides

“Nerve agents” Somewhat chemically similar to sarin, VX

Compounds of special concern to the EPA Priority for review under Food Quality Protection Act

Cholinesterase inhibitors Inhibits breakdown of acetylcholine Major consequences throughout nervous system Cognitive effects, among others

Acetylcholinesterase Inhibition

Chlorpyrifos Toxicity

Acute exposure Numbness, headache, dizziness, nausea, difficulty breathing, loss of

consciousness, convulsions, paralysis

Chronic exposure Cognitive impairment, disorientation, depression, lack of

coordination, speech difficulties

Other effects Lack of evidence for carcinogenic effect Possible endocrine disruptor!

Developmental Effects

Prenatal exposure Significant growth deficits in length and birthweight, increase in birth

defects Neurotoxicity Disruption of brain development at sub-acetylcholinesterase inhibiting

levels

Early childhood effects Measured umbilical cord blood concentrations at delivery >6.17 pg/g “high exposure” group Associated with significant psychomotor and cognitive delays at 36

months

Dose-Response AssessmentChild ingestion in an agricultural setting

EPA Reference Dose

RfD = 0.003 mg/kg/day

Dow Chemical Company: Sixteen human male volunteers ingested 0, 0.014, 0.03, or 0.10 mg/kg/day of

chlorpyrifos 20 days at the low and mid dose; treatment of the high-dose group (0.1

mg/kg/day) discontinued after 9 days due to a runny nose and blurred vision in one individual

Mean plasma ChE in this group was inhibited by about 65%

UF = 10 for human variability FQPA, 1996: additional UF of 10 for children and females <50 years old

“Low-to-mid confidence” in estimated RfD

IRED Human Health Assessment

Prenatal chlorpyrifos exposure

Average birthweight in “high exposure” cohort = 3.24 kg Lowest observed umbilical plasma concentration = 6.17 pg/g

Average adult plasma volume = 3.0 L 3.0 L * (1.025 kg/L) / 70 kg = 42 g plasma/ kg body weight

42 g/kg * 3.24 kg = 136.22 g plasma/infant (6.17 pg chlorpyrifos/ g plasma) * 136.22 g plasma = 840.48 pg/infant

So how many mg/kg? 840.48 pg/infant * (1 mg/1,000,000,000 pg) * (1 infant/3.24 kg) = 2.59 * 10-7 mg/kg at birth!! – about 100 times smaller than EPA RfD

significant psychomotor and cognitive delays at 36 months

Exposure Assessment

Exposure Routes

Ingestion Considered primary risk for Chlorpyrifos exposure for general

population Metabolites present in urine in 82% of US adults

Inhalation Requires presence of aerosolized pesticides Particular risk for applicators, mixer-loaders

Dermal Occupational exposures “Take-home” exposures

Agricultural workers and their families

Much higher concentrations of chlorpyrifos in home

Correlates with proximity to orchards/application zones

Accumulates on household surfaces, dust, dirt

Lingers after application

Chemical fate

Biological half-life Approx. 10-30 hours Metabolites excreted in urine

Soil half-life 60-120 days Sensitive to sunlight, microbial digestion Oxidation to chlorpyrifos oxon Little burden in water supply

Indoor half-life Estimated around 30 days Accumulates on sorbant surfaces

Child vulnerability

Children living in agricultural homes: Average of 0.52 ug chlorpyrifos/ pair of hands

Dermal dose 3% absorption / 3.24 kg newborn = 4.8 * 10-8 mg/kg

Oral dose Hand-to-mouth behavior 100% absorption / 3.24 kg newborn = 1.6 * 10-4 mg/kg

Inhalation dose 30 ug/m3 24 hours after pesticide application 60 times higher than EPA limit!

Risk Summary

EPA RfD: 0.0003 mg/kg/day for children

Prenatal exposure with significant developmental effects: Approx. 2.59 * 10-7 mg/kg at birth

Significant exposures arising from: Agricultural communities Drinking water

U.S. allowable lifetime dose = 20 ug/L

Current standards are woefully inadequate to prevent long-term developmental consequences.

Precautionary Assessment

Community / Social Issues

Parameter Score

Goal 2

Need 2

Future Generations 3

Democratic, community based process 2

Alternatives 3

Total 12/15

Exposure IssuesExposure Issues  Exposure 3

Multiple exposures 3

Children exposed 5

Consumer products 3

Occupational exposure 3Food exposure 3Total 20/20

Hazard/Toxicity

Hazard 9

Individual Sensitivity 3

Ecological hazard 3

Volume 5

Persistent 1

Bioaccumulation 2

Uncertainty 2

Total 25/30

Risk Management

Risk Perception

“Pesticide Drift” and children in California http://www.npr.org/templ

ates/story/story.php?storyId=123817702

Dow Chemical on Chlorpyrifos and kids http://

www.chlorpyrifos.com/myths-vs-facts.htm

Registration review

Docket opened May 2009

Human health assessment Public comment period July-September of this year Scoping: lack of emphasis on developmental toxicology data!

Environmental/endangered species impact assessment Public comment October-December 2013

Final registration decision in 2015

Recent regulatory action

New limitations to protect salmon, steelhead under Endangered Species Act announced in September 2009

Created in conjunction with the National Marine Fisheries Service

New labeling guidelines

Limitations on application: buffer zones, increased environmental monitoring, fish mortality data

References Eskenazi, et al. Exposures of children to organophosphate pesticides and their potential adverse health

effects.

Fenske, et al. Children's exposure to chlorpyrifos and parathion in an agricultural community in central Washington State.

Fenske, et al. Biologically based pesticide dose estimates for children in an agricultural community.

Fenske, et al. Potential exposure and health risks of infants following indoor residential pesticide applications.

Gore. Environmental Toxicant Effects on Neuroendocrine Function.

Griffin, et al. Oral and dermal absorption of chlorpyrifos: a human volunteer study.

Gurunathan, et al. Accumulation of chlorpyrifos on residential surfaces and toys accessible to children.

Rauh, et al. Impact of Prenatal Chlorpyrifos Exposure on Neurodevelopment in the First 3 Years of Life Among Inner-City Children.

Simcox, et al. Pesticides in household dust and soil: exposure pathways for children of agricultural families.

Slotkin and Seidler. The alterations in CNS serotonergic mechanisms caused by neonatal chlorpyrifos exposure are permanent.

Resources EPA - Chlorpyrifos Fact Sheet:

http://www.epa.gov/pesticides/reregistration/REDs/factsheets/chlorpyrifos_fs.htm

EPA - Chlorpyrifos Risk Information: http://www.epa.gov/iris/subst/0026.htm

EPA - Chlorpyrifos Interim Risk Management Decision: http://www.epa.gov/oppsrrd1/reregistration/chlorpyrifos/

ATSDR - Chlorpyrifos ToxFAQs: http://www.atsdr.cdc.gov/tfacts84.html

Pesticide Action Network – Chlorpyrifos: http://www.pesticideinfo.org/Detail_Chemical.jsp?Rec_Id=PC33392

National Agricultural Statistics Service - Agricultural Chemical Use Database: http://www.pestmanagement.info/nass/app_usage.cfm

National Resources Defense Council - Our Children At Risk: http://www.nrdc.org/health/kids/ocar/chap5b.asp

Dow Chemical - Chlorpyrifos Protects: http://www.chlorpyrifos.com/

NPR - "Pesticide drift eluding efforts to combat it", 2/28/10:http://www.npr.org/templates/story/story.php?storyId=123817702

Questions?