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Chlorpyrifos ENV H 572 Hilary Zetlen. Chlorpyrifos  Organophosphate pesticide  Marketed by Dow Chemical since 1965  Domestic and agricultural uses.

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Presentation on theme: "Chlorpyrifos ENV H 572 Hilary Zetlen. Chlorpyrifos  Organophosphate pesticide  Marketed by Dow Chemical since 1965  Domestic and agricultural uses."— Presentation transcript:

1 Chlorpyrifos ENV H 572 Hilary Zetlen

2 Chlorpyrifos  Organophosphate pesticide  Marketed by Dow Chemical since 1965  Domestic and agricultural uses

3 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

4 Annual use, Lbs. (% crop treated)

5 Regulatory Standing  CERCLA  Reportable quantity of release = 1 lb.  Clean Water Act  Allowable level = 20 ug/ L  FDA  ppm on food  FIFRA / EPA  Currently undergoing registration review  NRDC / PAN requesting revocation of registration  Final decision in 2015

6 Stakeholders  Dow Chemical Corp. and pesticide manufacturers  Agribusiness, small farmers, and agricultural communities  Consumers  Government agencies  The environment

7 Hazard Identification

8 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

9 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

10 Acetylcholinesterase Inhibition

11 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!

12 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

13 Dose-Response Assessment Child ingestion in an agricultural setting

14 EPA Reference Dose  RfD = 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

15 IRED Human Health Assessment

16 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 = g plasma/infant  (6.17 pg chlorpyrifos/ g plasma) * g plasma = pg/infant  So how many mg/kg?  pg/infant * (1 mg/1,000,000,000 pg) * (1 infant/3.24 kg) =  2.59 * mg/kg at birth!! – about 100 times smaller than EPA RfD  significant psychomotor and cognitive delays at 36 months

17 Exposure Assessment

18 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

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20 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

21 Chemical fate  Biological half-life  Approx hours  Metabolites excreted in urine  Soil half-life  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

22 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 * mg/kg  Oral dose  Hand-to-mouth behavior  100% absorption / 3.24 kg newborn = 1.6 * mg/kg  Inhalation dose  30 ug/m 3 24 hours after pesticide application  60 times higher than EPA limit!

23 Risk Summary  EPA RfD: mg/kg/day for children  Prenatal exposure with significant developmental effects:  Approx * 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.

24 Precautionary Assessment

25 Community / Social Issues ParameterScore Goal2 Need2 Future Generations3 Democratic, community based process2 Alternatives3 Total12/15

26 Exposure Issues Exposure3 Multiple exposures3 Children exposed5 Consumer products3 Occupational exposure3 Food exposure3 Total20/20

27 Hazard/Toxicity Hazard 9 Individual Sensitivity3 Ecological hazard3 Volume5 Persistent 1 Bioaccumulation2 Uncertainty2 Total25/30

28 Risk Management

29 Risk Perception  “Pesticide Drift” and children in California  ates/story/story.php?story Id= ates/story/story.php?story Id=  Dow Chemical on Chlorpyrifos and kids  om/myths-vs-facts.htm

30 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

31 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

32 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.

33 Resources  EPA - Chlorpyrifos Fact Sheet:  EPA - Chlorpyrifos Risk Information:  EPA - Chlorpyrifos Interim Risk Management Decision:  ATSDR - Chlorpyrifos ToxFAQs:  Pesticide Action Network – Chlorpyrifos:  National Agricultural Statistics Service - Agricultural Chemical Use Database:  National Resources Defense Council - Our Children At Risk:  Dow Chemical - Chlorpyrifos Protects:  NPR - "Pesticide drift eluding efforts to combat it", 2/28/10:http://www.npr.org/templates/story/story.php?storyId=

34 Questions?


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