Diazinon Profile

Diazinon Profile

QUICK SUMMARY

  • A pesticide used to kill ticks, mites, and roundworms on various crops; its use is declining
  • Associated cancers: Lung cancer, non-Hodgkin lymphoma (limited evidence)
  • Most important route of exposure: Ingestion, skin contact
  • Uses: Control of insects on berries, fruits, nuts, ground crops, cereals, tobacco, and Christmas trees
  • Occupational exposures: Via applying or manufacturing diazinon
  • Environmental exposures: Primarily via food, but food residue levels tend to be low
  • Fast fact: Domestic use of diazinon is prohibited in Canada.

General Information

Diazinon is an organophosphate pesticide used as an insecticide, acaricide (for ticks and mites), and nematicide (for nematodes or roundworms).[1] Depending on purity, it may be a colourless oil to an amber or brown liquid. Diazinon’s chemical name is O,O-diethyl O-2-isopropyl-6-methylpyrimidin-4-yl phosphorothioate, and it is sold under trade names such as Diazol®, Protector Ear Tags®, and Diazol Oil®.[1,2] As of 2016, there are nine products containing diazinon as an active ingredient registered with the Canadian Pest Management Regulatory Agency (PMRA), none of which are registered for domestic use.[2]

The International Agency for Research on Cancer (IARC) reclassified diazinon as Group 2A, probably carcinogenic to humans, in its 2015 assessment of the carcinogenicity of five organophosphate pesticides.[3] IARC’s review looked at studies of agricultural exposures in the USA and Canada, which found limited evidence of carcinogenicity in humans for lung cancer and non-Hodgkin lymphoma.[4,5,6] There was also limited evidence that diazinon causes cancer in animals, but convincing mechanistic evidence that it can induce DNA or chromosomal damage in animal and cell culture studies.

Diazinon exposure in humans can lead to a variety of symptoms and effects, depending on the degree of exposure.[7] It typically affects the nervous system, causing symptoms such as headache, dizziness, anxiety, eye pupil constriction, and in extreme cases, difficulty breathing, coma, or death.[8]

Regulations and Guidelines

Occupational Exposure Limits (OEL)

Canadian Jurisdiction OEL (mg/m3)
Canadian Labour Code[9] 0.01 [TWA; IFV; Skin]
AB[10] 0.01 [TWA; skin]
BC[11] 0.01 [TWA; v; skin]
NB[12] 0.01 [TWA; skin]
MB[13], NS[14], NL[15], ON[16], PE[17] 0.01 [TWA; IFV; skin]
QC[18] 0.1 [TWA; skin]
YT[19] 0.01 [TWA; skin] 
0.03 [stel; skin]
NT[20], SK[21], NU[22] 0.01 [TWA; IFV; skin] 
0.03 [stel; IFV, skin]
Other Jurisdictions OEL (mg/m3)
ACGIH 2018 TLV[23] 0.01 [TWA; IFV; skin]
mg/m3 = milligrams per cubic meter
TWA = time-weighted average, assuming a typical 8-hour workday and a 40-hour workweek of a chemical substance present in the air in a worker’s respiratory zone
IFV = inhalable fraction and vapour
skin = easily absorbed through the skin; identifies substances that contribute significantly to overall exposure by the skin route
v = inhalable fraction, vapour and aerosol
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
Ontario Ambient Air Quality Criteria 24 hours: 3 µg/m3 2016[24]
British Columbia’s Contaminated Sites Regulation

Sets soil standards for the protection of human health:
Agricultural and low density residential sites: 10 μg/g
Urban park and high density residential sites: 20 μg/g
Commercial and industrial sites: 150 μg/g

Drinking water: 20 μg/L

2017[25]
Quebec’s Regulation Respecting the Quality of Drinking Water MAC = 0.014 mg/L 2015[26]
Canadian Drinking Water Guidelines MAC = 0.02 mg/L 2017[27]
Health Canada’s Maximum Residue Limits for Foods Food type: 
Cantaloupes, watermelons: 0.25 ppm 
Swiss chard: 0.25 ppm 
Cucumbers: 0.5 ppm 
Brussels sprouts: 0.5 ppm 
Strawberries: 0.75 ppm 
Kale, spinach: 0.75 ppm 
Apricots, plums, pears: 0.75 ppm 
Range: 0.25-0.75 ppm
2017[28]
Agreement Respecting the Great Lakes Basin Ecosystem 0.08 µg/L 1987[29]
CCME Water Quality Guideline Rank = “Medium hazard”  2008[30]
WHO Drinking Water Guideline Excluded from guideline values because it is “unlikely to occur in drinking-water” 2011[31]
µg/m3 = micrograms per cubic meter
MAC = maximum allowable concentration
ppm = parts per million
µg/L = micrograms per liter
CCME = Canadian Council of Ministers of the Environment
WHO = World Health Organization
Diazinon was not included in other Canadian government environmental guidelines reviewed.[32,33]

Canadian Legal Status[34]

Jurisdiction Legislation Title Notes
Federal Pest Control Products Act, SC, 2002, c 28 Not included
  Pest Control Products Regulations, SOR/2006-124 Not included
Provincial/Territorial    
AB, BC, NB, NL, NT, NU, PEI, QC, SK, YK Multiple titles Not included
MB Non-Essential Pesticide Use Regulation, Man Reg 285/2014 Diazinon is not allowed for domestic/cosmetic use.
NS List of Allowable Pesticides Regulations, NS Reg 181/2010 Diazinon is not allowed for domestic/cosmetic use.
ON Pesticides Act, RSO 1990, c P. 11, as amended by the Cosmetic Pesticides Ban Act, 2008, S.O. 2008, c. 11 – Bill 64 – Assented to: June 18, 2008 Diazinon is not allowed for domestic/cosmetic use.

Several provincial, territorial, and municipal governments have passed laws to reduce the risk of pesticide products to human health and the environment. These may include restrictions on sales, production, or trade.[35,36] Although several provinces and one territory have implemented some form of cosmetic pesticide policy (QC, 2003; NB, 2009; ON, 2009; AB, 2010; PEI, 2010; NS, 2010; NL, 2012; YK 1994), only the Ontario and Nova Scotia legislation is considered strong enough to significantly reduce cosmetic pesticide exposure.[25] For example, Ontario’s Cosmetic Pesticide Ban Act, which has the most comprehensive restrictions on lawn and garden pesticides in North America, prohibits the cosmetic use of over 250 pesticide products and over 95 pesticide ingredients, including diazinon.[37]

Main Uses

Diazinon is an organophosphate pesticide used as an insecticide, acaricide (for ticks and mites), and nematicide (for nematodes or roundworms).[1] Diazinon is non-systemic, which means it must come into direct contact with the target species and does not circulate within the plant. It may be applied as dust, granules, spray, seed dressing, and within impregnated materials.[1] Diazinon is primarily used in the agricultural sector and on livestock, although its use is being reduced in Canada.[38] Diazinon is not available for domestic use in Canada.[2]

Historically, diazinon was widely used in Canada across a range of settings, such as for lawn, turf, and home gardens; however, concerns regarding its toxicity led to phase-out programs in North America beginning in 2004.[8,39] Diazinon has been banned for use in the United States on golf courses and sod farms since 1988, after decimating congregating bird flocks.[7]

Diazinon is used in the agricultural sector.[38] Diazinon is currently applied in Canada for selected insect control on berries, fruits, nuts, ground crops, cereals, tobacco, livestock, and Christmas trees. Several applications were recently subjected to a phase-out period according to a PMRA re-evaluation in 2013. For critical uses of diazinon, where no alternative products were identified, longer-term phase-outs were implemented to allow transition strategies and alternative risk management tools to be developed. The phase-out included ceasing the use of diazinon for fruit trees (including apricot, peach, plum) by December 2013, and for Christmas trees, several berries (strawberries, raspberries, loganberry, gooseberry), root vegetables (carrots, radish, turnip, rutabaga), fruit trees (apple, pear), and tobacco by December 2016. The PMRA stated that using diazinon for soil drenching and for ear tag applications remains acceptable. Soil drenching is an application method where a mixture of pesticide and water is applied directly to the base of an infected tree. Ear tags are often used to control fleas and ticks in livestock.[1]

Canadian Production and Trade

Since November 2006, the PMRA has tracked and reported sales information on Canadian pesticides. There was between 50,000-100,000 kilograms of active ingredient (kg a.i.) of diazinon sold in Canada in 2010, 2011, and 2012.[40] Less than 50,000 kg a.i. of diazinon was sold in Canada in 2009.[41] In 2008, diazinon was ranked as having the 10th highest insecticide sales per kg a.i., with more than 50,000 kg a.i. sold in Canada in 2008.[42] For the remaining years reported, diazinon was not among the top 10 insecticides sold in Canada.

The application and sales of diazinon varies considerably by each province in part due to the pest profile of each region. Diazinon was listed as one of the top 10 pesticide active ingredients by sales volume in BC, PE, NS, and NB in 2003.[43] Out of the three provinces where kg a.i. data is available, BC had the highest sales volume, with an average of 27,796 kg a.i. sold per annum between 2003-2010.[44] In contrast, 7,979 kg a.i. were sold in Ontario, and 2,542 kg a.i. were sold in Alberta in 2008.[45,46]

TradeMap lists diazinion export and import data; however, reporting for pesticides is not standardized and the data is incomplete.[47]

Environmental Exposures Overview

Food is considered the primary source of human exposure to diazinon, although food residue levels tend to be low.[8] Pesticide residues, including diazinon, are monitored by the Canadian Food Inspection Agency (CFIA) under the National Chemical Residue Monitoring Program (NCRMP).[48] To a lesser extent, people may be exposed when diazinon is applied agriculturally nearby or in urban areas (lawns and gardens). This would occur through touching recently sprayed plants or from drinking contaminated waters.[8] An individual may be exposed through inhalation, skin contact, or ingestion.

Diazinon may enter the environment from agricultural applications, where it can be present in the soil, air, surface waters, and plant surfaces. It may be present in the air as either a vapour or a particulate. Diazinon breaks down relatively quickly in the environment with a half-life ranging from an hour to two weeks, depending on local conditions.[8,49] Diazinon is metabolized in animals that may come into contact with it, and it does not bioaccumulate or biomagnify.[8]

Occupational Exposures Overview

Workers may be exposed to diazinon through inhalation, ingestion, or dermal absorption.[8]

Agricultural workers (such as farmers, farm managers, and labourers) who apply this pesticide, along with those who manufacture it, are the most likely to be exposed at work.[3,8] Para-occupational exposure to this pesticide is also possible in children and family members of those who apply and use diazinon.[50] The potential for occupational exposure is expected to decrease substantially when the PMRA phase-out period ends in December 2016 since diazinon will no longer be available to apply by air-blast, spray, dusts, or granules. Only ear tag and soil drenching will be acceptable.[38]

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. Harper B, Luukinen B, Gervais J, Buhl K, Stone D. National Pesticide Information Center (NPIC)’s Diazinon Technical Fact Sheet(2009)
2. Pest Management Regulatory Agency (PMRA). Pesticide Label Search (Search term: diazinon, accessed September 2015)
3. International Agency for Research on Cancer (IARC). Monograph Volume 112: Evaluation of five organophosphate insecticides and herbicides (2015) (PDF)
4. Waddell BL, Zahm SH, Baris D, Weisenburger DD, Holmes F, Burmeister LF, Cantor KP, Blair A. “Agricultural use of organophosphate pesticides and the risk of non-Hodgkin’s lymphoma among male farmers (United States).” Cancer Causes Control 2001;12:509-517.
5. McDuffie HH, Pahwa P, McLaughlin JR, Spinelli JJ, Fincham S. “Non-Hodgkin’s lymphoma and specific pesticides exposures in men: cross-Canada study of pesticides and health.” Cancer Epidemiol Biomark Prev 2001;10:1155-1163.
6. Guyton KZ, Loomis D, Gross Y, El Ghissassi F, Benbrahim-Tallaa L, Guha N, Scoccianti C, Mattock H, Straif K. “Carcinogenicity of tetrachlorvinphos, parathion, malathion, diazinon, and glyphosate.” The Lancet Oncology 2015;16, 490–491.
7. Toxipedia. Diazinon (Search term: Diazinon, accessed September 2015)
8. Agency for Toxic Substances and Disease Registry (ATSDR). Public Health Statement: Diazinon (2008)
15. Government of Newfoundland and Labrador. Regulation 5,12 Occupational Health and Safety Regulations (2012)
17. Government of Prince Edward Island. Occupational Health and Safety Act Regulations Chapter 0-1, 119 (2013) (PDF)
19. The Canadian Legal Information Institute (CanLII). Yukon’s Occupational Health Regulations, O.I.C. 1986/164 (2012) (PDF)
20. Government of the Northwest Territories. Occupational Health and Safety Regulations, R-039-2015 (2016) (PDF)
21. Government of Saskatchewan. The Occupational Health and Safety Regulations, 1996 (2016) (PDF)
22. The Canadian Legal Information Institute (CanLII). Government of Nunavut’s Occupational Health and Safety Regulations, Nu Reg 003-2016 (2010)
23. Occupational Safety and Health Administration (OSHA). Annotated PELs (2018)
24. Ontario Ministry of the Environment and Climate Change. Ontario’s Ambient Air Quality Criteria (2016)
25. Government of British Columbia. Contaminated Sites Regulation B.C. Reg. 375/96 (2017)
28. Health Canada. Maximum Residue Limits for Pesticides Search term: ‘diazinon’
29. International Joint Commission. Revised Great Lakes Water Quality Agreement of 1978(1987) (PDF)
30. Canadian Council of Ministers of the Environment (CCME). National Classification System for Contaminated Sites: Guidance Document (2008) (PDF)
32. Health Canada. Cosmetic Ingredient Hotlist (2015)
34. The Canadian Legal Information Institute (CanLII). The Canadian Legal Information Institute website
37. Government of Ontario. Pesticides Act (2015)
39. US Environmental Protection Agency (EPA). Diazinon: Phase Out of all Residential Uses of the Insecticide> (2004)
44. Wins-Purdy, A. 2010 Pesticide Sales in British Columbia (2013)
47. International Trade Centre. TradeMap (2014) (Free subscription required)
48. Canadian Food Inspection Agency. Chemical Residues in Food (2016)
49. Toxicology Data Network (TOXNET). Hazardous Substance Database (Search term: ‘diazinon,’ accesses September 2015)
50. Arcury TA, Grzywacz JG, Barr DB, Tapia J, Chen H, Quandt SA. “Pesticide urinary metabolite levels of children in eastern North Carolina farmworker households.” Env Health Perspect 2007;115:1254-1260.

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