Chlorpyrifos Factsheet

What is chlorpyrifos? diarrhea and blurred vision. At Chlorpyrifos is an organophosphate insecticide used higher doses, abdominal in agriculture primarily on cotton, oranges, corn, and cramps, vomiting, sweating, almonds, among many other crops. Also known as tearing, muscular tremors, Lorsban (agricultural use products), among other pinpoint pupils, low blood trade names, and manufactured predominantly by pressure, slow heartbeat and difficulty breathing may 8 Dow AgroSciences, chlorpyrifos is one of the most be observed. widely used insecticides in the U.S. Nationwide in The Association of Occupational and Environmental 2001 (prior to the cancellation of residential uses) US Clinics (AOEC) lists all organophosphates generally EPA estimated that 11–16 million pounds of the and chlorpyrifos specifically as capable of causing insecticide were used, second only to malathion for 9 1 asthma in previously unaffected individuals. insecticide use. Exposure can also exacerbate asthmatic symptoms in Chlorpyrifos was widely used in homes as a individuals who already have the disease. residential insecticide (under the trade name In addition to acute symptoms, many recent studies Dorsban) through 2005 when its phaseout for those indicate that low-level exposure to chlorpyrifos uses was completed—the result of a U.S. interferes with the development of the mammalian Environmental Protection Agency regulatory nervous system.10 Neural cell replication and 2 decision based primarily on its hazards for children. differentiation are both affected, with a reduction in Although some agricultural uses were altered by this the number of neural connections observed in phaseout agreement—to reduce residue levels in exposed rats.11 harvested produce, agricultural use remains high. In California in 2004, 2.3 million pounds of chlorpyrifos Human epidemiological studies on pregnant women were reported sold.3 exposed to chlorpyrifos through involuntary home pesticide use demonstrate a link between in utero Exposure to chlorpyrifos exposure to chlorpyrifos and low birth weights and People can be exposed to chlorpyrifos by direct reduced head circumference of newborns. These dermal contact, contact with treated surfaces, effects were most significant for individuals whose ingestion of chlorpyrifos contaminated dust, and by genetic makeup is such that they produce low levels breathing air inside or outside treated buildings or of PON1, the enzyme responsible for detoxifying near fields where it was applied. Exposures also chlorpyrifos in the body.12 Chlorpyrifos is also a result from eating food contaminated with suspected endocrine disrupting compound; moderate 4,5 chlorpyrifos residues. Contact with flea collars doses have been shown to alter hormone levels in containing chlorpyrifos can also lead to exposure. animal studies.13 Chlorpyrifos is found in particularly high levels in In addition to heightened vulnerability to chlorpyrifos children. Data from the Center for Disease Control because of their developing nervous systems, and Prevention (CDC) showed that 93% of U.S. children are likely to be exposed to higher levels of residents sampled between 1999 and 2000 had chlorpyrifos than adults for several reasons. Children chlorpyrifos in their bodies. Children (6–11 years) eat, breathe, and drink more per pound of body showed levels almost twice as high as those of adults. weight than adults. Children also play on the floor Chronic exposure levels were 4.6 times the and in the grass where pesticide residues collect; and “acceptable” level for children and 3.0 times the they exhibit hand-to-mouth behaviors that increase 6 “acceptable” level for youth (12–19 years). their potential for exposure. Health Effects While the U.S. EPA lists chlorpyrifos as providing Organophosphate pesticides’ most well-known and evidence of no carcinogenicity, recent studies suggest documented effects are their inhibition of an enzyme possible links to both lung14 and prostate15 cancer. (acetyl cholinesterase), necessary for proper Chlorpyrifos is a significant air pollutant transmission of nerve impulses.7 Symptoms of low- Chlorpyrifos is a semi-volatile chemical that readily dose exposure may include headaches, agitation, leaves in gas form from leaf and soil surfaces to inability to concentrate, weakness, tiredness, nausea, become airborne, especially when outdoor Ecological Effects temperatures are high. A study done in July and Chlorpyrifos is moderately to very highly toxic to August 2004 and 2005 in Lindsay, California, birds, honeybees, fish, and aquatic organisms. demonstrated the presence of chlorpyrifos in the air According to the EPA, just a single application of near homes in this agricultural community. Over 100 chlorpyrifos poses a risk to small mammals as well.18 air samples were collected near homes and three- It is a persistent chemical that accumulates in the quarters of the samples had detectable levels. Eleven tissue of aquatic organisms and has a half-life in soil percent of the samples were above the levels ranging from 60 days to one year depending on determined to be “acceptable” for a 24-hour exposure climate and soil type.19 by children. The highest concentration observed was nearly eight times the allowable level.16 Air monitoring studies conducted by the California Air Resources Board also indicated the potential for high exposures in areas near application sites.17 Revised October 2006

1 U.S. Environmental Protection Agency. University, Occupational Medicine Group for 13 a) Rawlings, NC, Cook, SJ, and Waldbillig, Pesticide Industry Sales and Usage: 2000 and the Association of Occupational and D, Effects of the pesticides carbofuran, 2001 Market Estimates. Available at Environmental Clinics, chlorpyrifos, dimethoate, lindane, triallate, http://www.epa.gov/oppbead1/pestsales/index http://www.aoec.org/aoeccode.htm. trifluralin, 2,4-D, and pentachlorophenol on .htm. 10 Slotkin, TA, Levin, ED, Seidler, FJ, the metabolic endocrine and reproductive endocrine system in ewes, J Tox. Envi. 2 Chlorpyrifos Revised Risk Assessment and Comparative Developmental Neurotoxicity of Organophosphate Insecticides: Effects on Health, 1998, 54: 21–36. Agreement with Registrants, U.S. EPA, June b) Keith, LH, Environmental Endocrine 2000, Brain Development Are Separable from Systemic Toxicity, Envi. Health Persp. 2006, Disruptors: A Handbook of Property Data, http://www.epa.gov/pesticides/op/chlorpyrifo Wiley Interscience (New York, 1997). s/agreement.pdf. 114(5): 746-51 and references cited therein. 11 a) Aldridge JE, Seidler FJ, Meyer A, Thillai I, 14 Lee, WJ, A. Blair, JA Hoppin, JH Lubin, JA 3 CA Pesticide Sales Data for 2004, California Rusiecki, DP Sandler, M Dosemeci, MC Department of Pesticide Regulation, Slotkin TA, Serotonergic Systems Targeted by Developmental Exposure to Chlorpyrifos: Alavanja. Cancer incidence among pesticide Sacramento, CA, applicators exposed to chlorpyrifos in the http://www.cdpr.ca.gov/docs/mlassess/nopds Effects during Different Critical Periods. Envi. Health Persp. 2003, 111(14): 1736-43. Agricultural Health Study. J Natl Cancer Inst. old.htm. The 2004 data are the most recent 1;96(23):1781-9. 2004. available at the time this report was written. b) Jameson, RR, Seidler, FJ, Qiao, D, Slotkin, TA, Chlorpyrifos Affects Phenotypic 15 Alavanja, MCR, C Samanic, M Dosemecil, J 4 Agency for Toxic Substances and Disease Outcomes in a Model of Mammalian Lubin, R Tarone, CF Lynch, C Knott, K Registry. ToxFAQs(tm) for Chlorpyrifos. Neurodevelopment: Critical Stages Targeting Thomas, JA Hoppin, J Barker, J Coble, DP September 1997. Available at Differentiation in PC12 Cells, Envi. Health Sandler and A Blair. Cancer: possible http://www.atsdr.cdc.gov/tfacts84.html. Persp. 2006, 114(5): 667-72. association with increase risk of prostate 5 Fenske, RA, L. Chensheng, D. Barr, and L. c) Aldridge, JE, Meyer, A, Seidler, FJ, cancer. Use of Agricultural Pesticides and Needham. Children’s exposure to Slotkin, TA, Alterations in Central Nervous Prostate Cancer Risk in the Agricultural Chlorpyrifos and Parathion in an agricultural System Serotonergic and Dopaminergic Health Study Cohort. Am J of Epidem community in central Washington state. Synaptic Activity in Adulthood after Prenatal 157:800–814. 2003. Environmental Health Perspectives 2002; or Neonatal Chlorpyrifos Exposure, Envi. 16 Mills K and S Kegley. Air Monitoring for 110(5):549-553. Health Persp. 2005, 113(8): 1027-31. Chlorpyrifos in Lindsay, California: June- 6 Schafer, K.S., M. Reeves, S. Spitzer and S.E. 12 a) Whyatt RM and Barr, DB, Measurement of July 2004 and July-August 2005. Pesticide Kegley. Chemical Trespass: Pesticides in our organophosphate metabolites in postpartum Action Network, San Francisco, CA. April bodies and corporate accountability. Pesticide meconium as a potential biomarker of 2006. Action Network, San Francisco, CA. 2004. prenatal exposure: A validation study, Envi 17 Report for the Application and Ambient Air http://www.panna.org/campaigns/docsTrespa Health Persp, 2001, 109(4): 417-20. Monitoring of Chlorpyrifos (and the Oxon ss/chemicalTrespass2004.dv.html. b) Whyatt RM, Rauh V, Barr DB, et al. Analogue) in Tulare County during 7 Toxicology Information Briefs: Prenatal Insecticide Exposures and Birth Spring/Summer 1996, California Air Cholinesterase Inhibition, Extension Weight and Length among an Urban Minority Resources Board, Test Report #C96-040 and Toxicology Network, Cooperative Extension Cohort, Envi. Health Persp. 2004, # C96-041, April 7, 1998, Offices of Cornell University, Oregon State 112(10):1125-32. http://www.cdpr.ca.gov/docs/empm/pubs/tac/ University, the University of Idaho, and the c) Berkowitz GS, Wetmur JG, Birman-Deych chlrpfs.htm. E, et al., In Utero Pesticide Exposure, University of California at Davis and the 18 See reference #2 Institute for Environmental Toxicology, Maternal Paraoxonase Activity, and Head Michigan State University. Circumference, Envi. Health Persp. 2004, 19 Extension Toxicology Network. http://extoxnet.orst.edu/tibs/cholines.htm. 112(3):388-91. “Chlorpyrifos.” June 1996. Available at (d) Furlong, CE, Holland N, Richtera RJ, http://extoxnet.orst.edu/pips/chlorpyr.htm. 8 Reigert, JR and Roberts, JR, Recognition and Bradman A, Ho A and Eskenazi B. PON1 Management of Pesticide Poisoning, 5th ed., status of farmworker mothers and children as US EPA, 1999, a predictor of organophosphate sensitivity. http://www.epa.gov/pesticides/safety/healthca Pharmacogenetics and Genomics 2006, re/handbook/contents.htm. 16:183–190. 9 AOEC Exposure Codes, George Washington

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