PESTICIDES – POSSIBLE CARCINOGEN (IARC 2B)
- 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.
Dichlorvos is a synthetic organic chemical used as a pesticide. It is a dense, sweet smelling, and colourless liquid which evaporates easily into air and reacts readily with water. Dichlorvos is a member of the organophosphate group of pesticides. 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. 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.
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. An analysis of data from the Agricultural Health Study in the US did not find elevated cancer rates in pesticide applicators exposed to dichlorvos.
Dichlorvos is highly toxic to the nervous system. Acute exposure to dichlorvos may cause nausea, fatigue, drowsiness, and headache. Coma, respiratory arrest, and death may result from high exposures.
Regulations and Guidelines
|Canadian Jurisdictions||OEL (mg/m3)|
|Canada Labour Code||0.1 (IFV) [sk, dsen]|
|SK, NT, 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]|
3 [stel, sk]
|Other Jurisdiction||OEL (mg/m3)|
|ACGIH 2020 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
|Veterinary New Drug List, Sec. 2: Food and Drug Act||Included||2001|
|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
μg/g = micrograms per gram
Canadian maximum residue level (MRL) limits
|Food Item(s)||MRL (ppm)|
|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
|Health Canada||DSL – high priority substance with lowest potential for exposure||2006|
|PMRA||Re-evaluation of dichlorvos – ongoing||2008[31,32]|
|Agreement Respecting the Great Lakes Basin Ecosystem||Listed as a “Hazardous Polluting Substance||1987|
DSL = domestic substance list
PMRA = Pest Management Regulatory Agency
Dichlorvos has been widely used as an insecticide since 1961. It is mainly used to control insects in food storage areas, greenhouses, and barns, and to control parasites in livestock and domestic animals. Dichlorvos is also used to control insects in workplaces. In general, dichlorvos is not used on outdoor crops.
Dichlorvos may be used in the form of dust, granules, pellets, impregnated resin strips, or concentrates. It can be diluted with other liquids and used as a spray, or incorporated into slow-releasing plastics.
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. 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). Dichlorvos may enter the environment through landfill waste contamination, accidental spills during transport, and leaks from storage containers. Dichlorvos does not bind easily to soil and moves through it quickly. However, its breakdown in soil is slower than in air or water. 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.
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. 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. 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.
Dichlorvos is not reportable to the National Pollutant Release Inventory. A search in the Household Products Database yielded five products, which included pest control strips and bed bug treatments.
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.
Workers with the highest potential for exposure to dichlorvos are those who produce and use it. 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.
- Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for Dichlorvos (1997) (PDF)
- International Programme on Chemical Safety (IPCS) INCHEM. Environmental Health Criteria 79: Dichlorvos (1989)
- International Programme on Chemical Safety (IPCS) INCHEM. Document: Evaluation of some Pesticide residues on food (1967)
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