Dichlorvos Profile

Dichlorvos Profile

QUICK SUMMARY

  • A pesticide used to control insects in food storage areas and on livestock
  • Associated cancers: Leukemia, forestomach and pancreatic tumours (animal studies only)
  • Most important route of exposure: Inhalation
  • Uses: Kills insects in food storage areas, greenhouses, and barns, and controls parasites in livestock and domestic animals
  • Occupational exposures: Via manufacturing or applying dichlorvos
  • Environmental exposures: Via its use in pest strips or sprays for insect control in homes and the public
  • Fast fact: Dichlorvos is not used on outdoor crops.

General Information

Dichlorvos is a synthetic organic chemical used as a pesticide.[1] It is a dense, sweet smelling, and colourless liquid which evaporates easily into air and reacts readily with water.[1] Dichlorvos is a member of the organophosphate group of pesticides.[1] It may also be referred to as DDVP, and trade names include Vapona®, Atgard®, Nuvan®, and Task®.[1,2] There are numerous other synonyms and product names; see the Hazardous Substances Data Bank (HSDB) for more information.[2] There are 10 products containing dichlorvos as an active ingredient registered with the Canadian Pest Management Regulatory Agency (PMRA), one of which is registered for domestic use.[3]

Dichlorvos has been classified by the International Agency for Research on Cancer (IARC) as Group 2B, possibly carcinogenic to humans. This classification is based on animal studies showing increased rates of leukemia and forestomach and pancreatic tumours in rats, and increased esophageal and forestomach tumours in mice following exposure.[4] An analysis of data from the Agricultural Health Study in the US did not find elevated cancer rates in pesticide applicators exposed to dichlorvos.[5]

Dichlorvos is highly toxic to the nervous system.[1] Acute exposure to dichlorvos may cause nausea, fatigue, drowsiness, and headache. Coma, respiratory arrest, and death may result from high exposures.[1]

Regulations and Guidelines

Occupational Exposure Limits (OEL) [6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]

Canadian Jurisdictions OEL (mg/m3)
Canada Labour Code 0.1 (IFV) [sk, dsen]
AB 0.1 [sk]
SK, NU 0.1 (IFV) [sk, sen]
0.3 (IFV) [stel, sk, sen]
BC, ON, 0.1 (IFV) [sk, sen]
NB, NL, PE, MB, NS 0.1 (IFV) [sk, dsen]
QC 0.9 [sk]
YT 1 [sk]
3 [stel, sk]
NT 0.9 [sk]
2.7 [sk, stel]
Other Jurisdiction OEL (mg/m3)
ACGIH 2018 TLV 0.1 (IFV) [sk, dsen]
mg/m3 = milligrams per cubic meter
IFV = inhalable fraction and vapour
sk = easily absorbed through the skin
dsen = dermal sensitization
sen = potential for sensitization
stel = short term exposure limit (15 min. maximum)
ACGIH = American Conference of Governmental Industrial Hygienists
TLV = threshold limit value

Canadian Environmental Guidelines

Jurisdiction Limit Year
Veterinary New Drug List, Sec. 2: Food and Drug Act Included 2001[21]
BC’s Contaminated Sites Regulation, BC Reg 375/96 Sets soil standards for the protection of human health:
Agricultural and low density residential sites: 8 μg/g
Urban park and high density residential sites: 15 μg/g
Commercial and industrial sites: 100 μg/g
2017[22]
μg/g = micrograms per gram
Dichlorvos was not included in other Canadian government environmental guidelines reviewed.[23,24,25,26,27,28]

Canadian Maximum Residue Level (MRL) Limits[29]

Food Item(s) MRL (ppm)
Tomatoes 0.25
Non-perishable packaged foods of low fat content (<6%) 0.5
Non-perishable packaged foods of high fat content (>6%) 2.0
ppm = parts per million

Canadian Agencies/Organizations

Agency Designation/Position Year
Health Canada DSL – high priority substance with lowest potential for exposure 2006[30]
PMRA Re-evaluation of dichlorvos – ongoing 2008[31,32]
Agreement Respecting the Great Lakes Basin Ecosystem Listed as a “Hazardous Polluting Substance 1987[33]
DSL = domestic substance list
PMRA = Pest Management Regulatory Agency
Dichlorvos was not included in other Canadian government chemical listings reviewed.[34,35,36]

Main Uses

Dichlorvos has been widely used as an insecticide since 1961.[4] It is mainly used to control insects in food storage areas, greenhouses, and barns, and to control parasites in livestock and domestic animals.[1] Dichlorvos is also used to control insects in workplaces.[37] In general, dichlorvos is not used on outdoor crops.[1]

Dichlorvos may be used in the form of dust, granules, pellets, impregnated resin strips, or concentrates.[4] It can be diluted with other liquids and used as a spray, or incorporated into slow-releasing plastics.[1]

Canadian Production and Trade

No evidence was located on Canadian production or trade of dichlorvos.

Environmental Exposures Overview

The general public is most likely to be exposed to dichlorvos by inhaling contaminated air. CAREX Canada’s environmental estimates indicate that levels of dichlorvos in outdoor air do not result in an increased risk of cancer (very low data quality). Unfortunately, no recent data or studies were identified for dichlorvos levels in indoor air.

The majority of environmental exposure to dichlorvos occurs through pest strips or sprays for insect control in homes and in public.[4,38] Dichlorvos is not known to bioaccumulate in plants or animals.[1] It evaporates easily into the air and can break down via a reaction with water vapour (this reaction is faster under warm and humid conditions).[1] Dichlorvos may enter the environment through landfill waste contamination, accidental spills during transport, and leaks from storage containers.[1] Dichlorvos does not bind easily to soil and moves through it quickly. However, its breakdown in soil is slower than in air or water.[1] Therefore, skin contact may occur via contaminated soil. On dry hard surfaces it can persist longer; on wood, 39% of dichlorvos may remain for up to 33 days.[37]

Small amounts of dichlorvos residue have been detected in food.[1,38] However, the general population is expected to be minimally exposed to dichlorvos through food and beverages. The World Health Organization and the Food and the Agriculture Organization of the United Nations have designated 0 – 0.004 mg/kg of body weight as an acceptable daily intake (ADI) of dichlorvos.[37] Unfortunately, no data was available for dichlorvos levels in food or beverages. As a result, CAREX Canada was not able to conduct an adequate environmental exposure assessment for this exposure route.

Drinking water is a potential route for exposure to dichlorvos.[37] CAREX Canada’s environmental estimates indicate that levels of dichlorvos in drinking water result in an increased risk of cancer (low data quality).

Exposure may also occur in populations living near hazardous waste sites containing dichlorvos (usually in the form of liquid solution or as solid plastic pellets or strips) or sites where it is manufactured, processed, or stored.[1]

Dichlorvos is not reportable to the National Pollutant Release Inventory.[39] A search in the Household Products Database yielded five products, which included pest control strips and bed bug treatments.[40]

US Household Products Database

Search Term Quantity Product Type
‘Dichlorvos’ 5 Bedbug treatment, mosquito traps, pest control strips

For more information, see CAREX Canada’s environmental exposure estimates for dichlorvos.

Occupational Exposures Overview

The most common route of occupational exposure to dichlorvos is through inhalation, however dermal contact can also occur.[1]

Workers with the highest potential for exposure to dichlorvos are those who produce and use it.[4] These occupations include chemical plant workers, transport workers, and pesticide applicators.

CAREX Canada has not prioritized diazinon for exposure estimate development. This is because a lack of exposure data precluded it in the past. However, the team is investigating new sources of data and methods in order to potentially address this exposure in the future.

Sources

1. Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for Dichlorvos (1997) (PDF)
2. Toxicology Data Network (TOXNET). Hazardous Substances Data Bank (Search term: “dichlorvos”)
3. Health Canada. Pesticide Label Search (2016)
4. International Agency for Research on Cancer (IARC). Monograph summary, Volume 53 (1991) (PDF)
5. Koutros S, Mahajan et al. Dichlorvos exposure and human cancer risk: results from the Agricultural Health Study. Cancer Causes and Control 2008;19:59-65.10.1007/s10552-007-9070-0.
11. Government of Newfoundland and Labrador. Regulation 5,12 Occupational Health and Safety Regulations (2012)
12. Government of the Northwest Territories. Occupational Health and Safety Regulations, R-039-2015 (2016) (PDF)
14. The Canadian Legal Information Institute (CanLII). Government of Nunavut’s Occupational Health and Safety Regulations, Nu Reg 003-2016 (2010)
16. Government of Prince Edward Island. Occupational Health and Safety Act Regulations Chapter 0-1 (2013) (PDF)
18. Government of Saskatchewan. The Occupational Health and Safety Regulations, 1996 (2016) (PDF)
19. The Canadian Legal Information Institute (CanLII). Yukon’s Occupational Health Regulations, O.I.C. 1986/164 (2012) (PDF)
20. Occupational Safety and Health Administration (OSHA). Annotated PELs (2018)
22. Government of British Columbia. Contaminated Sites Regulation B.C. Reg. 375/96 (2017)
25. The Canadian Legal Information Institute (CanLII). Ontario Drinking Water Quality Standards, O Reg 169/03 (2017)
26. The Canadian Legal Information Institute (CanLII). Regulation respecting the quality of drinking water, CQLR c Q-2, r 40 (2016)
27. Ontario Ministry of the Environment and Climate Change. Ontario’s Ambient Air Quality Criteria (2016)
28. Alberta Environment and Parks. Ambient Air Quality Objectives (2017)
30. Health Canada. Prioritization of the DSL (2006)
33. International Joint Commission. Revised Great Lakes Water Quality Agreement of 1978 (1978) (PDF)
34. Environment and Climate Change Canada. CEPA List of Toxic Substances (1999)
36. Canadian Council of Ministers of the Environment (CCME). National Classification System for Contaminated Sites (2008) (PDF)
37. World Health Organization. Guidelines for Drinking-water Quality. Fourth edition. (2011) (PDF)
38. US Environmental Protection Agency (EPA). Dichlorvos (2007)
39. Environment and Climate Change Canada. National Pollutant Release Inventory (NPRI) Facility Search (Substance name: ‘Dichlorvos’)
40. US Household Products Database (HPD). Household Products (Search term: ‘Dichlorvos’)

Other Resources

  1. Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for Dichlorvos (1997) (PDF)
  2. International Programme on Chemical Safety (IPCS) INCHEM. Environmental Health Criteria 79: Dichlorvos (1989)
  3. International Programme on Chemical Safety (IPCS) INCHEM. Document: Evaluation of some Pesticide residues on food (1967)

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