chlorpyrifos env h 572 hilary zetlen. chlorpyrifos organophosphate pesticide marketed by dow...
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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?