CHLORPYRIFOS

CHEMICAL NAME: 0,0-diethyl O-(3,5,6-trichloro-2-pyridyl) phosphorothioate

CAS REGISTRY NUMBER: 2921-88-2

CHEMICAL FAMILY: Organo-phosphate Insecticide

MOLECULAR FORMULAE: C9 H11 Cl3 NO3 PS

DESCRIPTION: Red liquid with mercaptan-type odour.

USAGE: Broad spectrum insecticide used on wide variety of crop types, for the control of locusts and is present in some cattle dips for the control of ticks and lice. Also registered for domestic gardens; as indoor insect control, termiticide, for pet products and commercial and industrial insect control.

Agricultural - insecticide

Industrial - termiticide and insecticide

Domestic - termiticide

TOLERANCE & EXPOSURE LEVELS: ACGIH TLV is 0.2 mg/m3 for chlorpyrifos. ACGIH STEL is 0.6 mg/m3 for chlorpyrifos.(1)

HEALTH EFFECTS: SHORT TERM: Chlorpyrifos is very toxic to humans, between 1 teaspoon and 1 ounce may be fatal. (7) Chlorpyrifos toxicity is considerably greater if administered orally compared to dermal. (11) Primary routes of exposure are inhalation, skin or eye contact. Inhalation exposure to high concentration may cause upper respiratory irritation, central nervous system depression headache, dizziness, increased sensitivity to epinephrine, irregular heartbeats, incoordination, muscle twitching, tremor, pinpoint pupils, blurred vision, tightness in chest, and convulsions. Eye contact may cause pain, moderate irritation.(6) Poisoning also impairs Central Nervous System. (2)

LONG TERM: Continual absorption at intermediate dosage may cause influenza-like illness which includes symptoms like weakness, anorexia and malaise.(2) Prolonged or repeated over exposure to the product Lorsban may result in delayed liver and or kidney damage. (1) Other chronic exposure effects are behavioural neurotoxicity and organo-phosphate induced delayed neuropathy. (11)

CARCINOGENICITY:This material is not considered to be a carcinogen by the National Toxicology Program, the International Agency for Research on Cancer, or the Occupational Safety and Health Administration. (1)

MUTAGENICITY: Chlorpyrifos was mutagenic in microbial inhibition assays.(5)

REPRODUCTIVE EFFECTS: No human data available.

BIO-ACCUMULATION: Animal studies suggest that Chlorpyrifos is rapidly absorbed and metabolised to 3,5,6-trichloro-2-pyridinal (TCP). The parent compound and metabolite are rapidly excreted in the urine. (2) 3,5,6-trichloro-2-pyridinol detected in urine of 5.8% of 6990 samples from general population (1976-80), mean in urine of pest controlllers in Texas:5.6-8.3 ug/l.(13)
Suspected Effects:

ANIMAL TOXICITY DATA: Acute Oral 163mg/kg Toxicity Category 11 Acute Dermal 1505mg/kg Toxicity Category 11 Avian Oral 76mg/kg Freshwater fish Rainbow Trout 3ppm Chlorpyrifos residues have been detected in the kidney and fat from cattle dipped once in a 0.025% emulsion. Fats of Australian cattle contained the breakdown product, 0,0-diethyl 0-(3,6- dichloro-2-pyridyl) phosphothioate after being treated with chlorpyrifos for cattle tick.(11)

CARCINOGENICITY: Two studies submitted to USA EPA, neither suggest carcinogenicity. (2)

REPRODUCTIVE EFFECTS: EPA evaluated 3 studies and determined that Chlorpyrifos is not teratogenic at levels up to 25mg/kg. Chlorpyrifos does not produce reproductive effects at dose levels up to 1.2mg/kg/day. (2)

MUTAGENICITY: Two assays in bacterial systems are weakly positive for DNA damage. (3)

Wildlife Data: Isolated in kurrawong autopsies from the Sydney region.(8) Detected in 1990 sampling of three eggs of Little Terns (0.06-0.36ppm), one liver sample from Little Terns (0.02ppm) and one Pelican egg (0.5ppm) from the Wallace Lake Colony, central coast of NSW. (15) When applied to freshwater ponds, cladocerans and copepods were killed and a 42% mortality rate in Mallard ducklings. (11)

ENVIRONMENTAL EFFECTS: Environmental Fate: US EPA consider there is insufficient data to fully assess the environmental fate of Chlorpyrifos.(2) Chlorpyrifos is tightly adsorbed by soil and not expected to leach significantly. Volatilisation from soil surface will contribute to loss.(13) Depending on soil type , microbial metabolism of Chlorpyrifos may have a half-life of up to 279 days.(2) Higher soil temperatures, lower organic content and lower acidity increases degradation of chlorpyrifos. Chlorpyrifos inhibits nitrification and nitrogen fixation marginally, many bacterial strains were unable to degrade it but some micro-organisms can use chlorpyrifos as their only source of carbon and nitrogen.(11) Where it is used in subterranean termite control it may remain effective for up to 5-17 years.(9) When apllied to sandy soil, a 50% loss was noted after 2 weeks and when applied to high organic matter soil, a 50% loss was noted after 8 weeks. (11) If released to water, chlorpyrifos partitions significantly from water column to sediments. Hydrolysis halflife at 25C in neutral conditions:35-78 days. Photolysis half life at water surface in mid summer is approx. 3-4 weeks. The desorption from sediment can contribute to long term residual concentration in water column. (13) Detected in water sampling from the Dundurrabin area and in a combined water/sediment sample from Dorrigo water supply. (12) If released to air will react in vapor phase with photochemically produced hydroxyl radicals with half life 6.34 hours. Detected in 14/123 ambient air samples collected at 10 U.S. locations (1980) with max concentration of 100ng/m3 and mean of 2.1ng/m3. (13) Air in 16 houses treated for subterranean termites according to label instructions average 1.38-3.07 ug/m3 one year after treatment and 1.32- 1.82 ug/m3, 2 years after treatment. These were above the air equivalent of Acceptable Daily Intake set by New York Department of Health: 1.0ug/m3 (adult) and 0.49 ug/m3 (child). (14) Water MRL: 0.002ppm Milk MRL: 0.2 ppm Cereal Grains: 0.1 ppm Apples MRL: 1.0 ppm Edible offal Meat MRL: 2.0 ppm (10)

EPA DATA GAPS:

NOTES: Highly toxic and irritating chlorides produced on combustion. (6) Some formulations may include the organo-chlorine, 1,1,1-trichloroethane as a solvent. Both chlorpyrifos and 1,1,1,trichloroethane have the potential of enhancing either the detoxication or the bioactivation of each other. The majority of other formulations use hydrocarbon solvents such as hexane or xylene. (11)

** Disclaimer: These sheets are designed as summary information and as such are a guide only.

References:

1.Canadian Centre of Occupational Health Database - CCINFO 1991.

2.EPA Pesticide Fact Sheet, Chlorpyrifos 1984

3 EPA Chlordane, Heptachlor Aldrin & Dieldrin 1987 Technical Support Document.

4.Pesticides and Human Health, W.H.Hallenbeck&K.M.Cunningham-Burns School of Public Health, Uni. of Illinois Chicago, Springer-Verlag 1985

5.Contemporary Issues in Pesticide Toxicology & Pharmacology, Dr Judith Marquis, Associate Professor of Pharmacology,Boston Uni. Karger 1986

6.Chemical Hazard Response Information System, US Dept. of Transportation.

7.Oil & Hazardous Materials - Technical Assistance Data System, US EPA

8.Tel Conversation: Dr L Llewelyn National Parks & Wildlife Service 6.11.90

9.A-Z of Chemicals in the Home. Toxic & Hazardous Chemicals Committee. 1986

10.NH&MRC MRL Standards Draft 1989

11.Centre for Human Aspects of Science and Technology, Pub 1., Chlorpyrifos

12. Coffs Harbour Chemical Database 1991.

13.Handbook of Environmental Fate and Exposure Data for Organic Chemicals, Ed. P.H.Howard Lewis Pub. Michigan 1991

14.Chlorpyrifos, Dr Mary O'Brien J.of Pesticide Reform, Vol8 No4 1989

15.NSW Department of Agriculture, Pesticide Analysis No. CP90/633-635 Re: Pelican Eggs, Little Tern - Wallace Lake Colony