Chlorothalonil
Full Profile
General Information
Chlorothalonil is a colourless and odourless white crystalline solid that is soluble in water. It is used as a fungicide for vegetable, fruit, field, and ornamental crops as well as lawns and turfs.[2] It may also be referred to as Daconil, Bravo, or 1,3-dicyanotetrachlorobenzene.[2] There are numerous other synonyms and product names; see HSDB for more information.[2]
Chlorothalonil has been classified by IARC Group 2B, possibly carcinogenic to humans:[3] although no studies of its carcinogenicity in humans are available,[3] chlorothalonil is a kidney and stomach carcinogen in rats and mice.[3] Additionally, chlorothalonil can cause irritation of the skin and contact dermatitis.[4] It may also cause irritation of the mucous membranes of the eye and respiratory tract.[2]
Chlorothalonil has been ranked by CAREX Canada as Group A (immediate high priority) for both the occupational and environmental settings. Prioritization was based on the carcinogenicity and other toxic properties of the substance, the prevalence of exposure in Canada, and the feasibility of assessing exposure.
Regulations and Guidelines
No occupational exposure limits for chlorothalonil in Canada or any other international bodies were located.
Canadian Environmental Guidelines
Chlorothalonil was not included in the Canadian government environmental guidelines reviewed.[5,6]
Canadian Maximum Residue Limits 2009[7]
| Food | MRL (ppm) |
|---|---|
| Celery | 15 |
| Beans, Broccoli, Brussels Sprouts, Cabbage, Cauliflower, Cucumbers, Melons, Onions, Pumpkins, Squash, Tomatoes, Wasabi |
5 |
| Cranberries | 2 |
| Carrots, Mushrooms, Parsnips | 1 |
| Blueberries | 0.6 |
| Cherries, Peaches, Nectarines | 0.5 |
| Peanuts | 0.3 |
| All other foods | 0.1 |
Canadian Agencies/Organizations
| Agency | Designation/Position | Year |
|---|---|---|
| Health Canada | DSL – high priority substance with lowest potential for exposure | 2006[8] |
Chlorothalonil was not included in other Canadian government chemical listings reviewed.[9]
Main Uses
Chlorothalonil has been produced for commercial use since 1969.[3] It is used as an agricultural and horticultural fungicide, bactericide and nematocide.[3] It is a broad spectrum, non-systemic pesticide to control fungal foliar diseases of vegetable, field, and ornamental crops.[2] It is typically used on the following crops: citrus fruits, currants, berries, bananas, tomatoes, green vegetables, coffee, peanuts, potatoes, onions and cereals.[4]
Chlorothalonil may also be used as a preservative in paints, adhesives, and wood; as an anti-mold and anti-mildew agent; and as a micro-biocide, algaecide, insecticide and aracnicide.[2,3]
Canadian Production and Trade
In Canada the major products sold with chlorothalonil as the active ingredient include Bravo, Daconil, Ridomil Gold, Rigo Exotherm Termil Protectant Fungicide.[11] Syngenta Crop Protection Canada Inc is a distributor of many pesticides and fungicides, including chlorothalonil. Chlorothalonil is sold by Syngenta under its trade name Bravo500.[14]
The BC and Ontario pesticide surveys report the amount of chlorothalonil used or sold in their respective provinces:
| Province | Sold/Used | Year |
|---|---|---|
| BC | 26 t | 1999[10] |
| BC | 33 t | 2003[11] |
| ON | 38 t | 2003[12] |
Occupational Exposures
Inhalation and dermal absorption are the most important routes of occupational exposure.[4]
Occupational exposure can occur during chlorothalonil production and application, and also by handling treated crops.[3] Workers involved in manufacturing or distribution facilities can be exposed via contaminated air or dermal exposures.[4] Farmers and pesticide applicators may be exposed via inhalation or dermal absorption during pesticide application or contact with treated crops.[4]
Chlorothalonil is also used in the forestry industry, potentially exposing tree planters[15] and workers in contact with treated wood such as wood processors and cabinet manufacturers.[4]
Environmental Exposures
Sources of environmental exposure include ingestion of crop residues on foods,[4] living in close proximity to agricultural uses, and contaminated water.[16,17]
Chlorothalonil is strongly adsorbed to suspended matter in water, and may biodegrade. It is rapidly degraded in soil[4] and does not bioaccumulate in mammals.[4] The amount of chlorothalonil residue on foods depends on application rate, time interval between application and harvest, and the type of crop.[4]
In 1996, the WHO reported that analysis across several countries showed undetectable or low concentrations of chlorothalonil on food samples. Risk of exposure is decreased further by preparation activities such as washing, peeling and cooking foods.[4]
The most recent Health Canada Total Diet Study where pesticides were included was conducted in 1998 in Whitehorse.[18] The average intake of Canadians was estimated to be 4.78 nanograms per kilogram of body weight per day, or 0.02% of the acceptable daily intake (ADI) as set by the WHO (18). Food tested included broccoli (3.1% of MRL), celery (<0.1% of MRL), and tomatoes, (<0.1% of MRL).[19]
Release of chlorothalonil is not reportable to the National Pollutant Release Inventory (NPRI).[20]
US Household Products Database
| US Household Products 2010[13] | ||
|---|---|---|
| Search Term | Quantity | Product Type |
| 'chlorothalonil' | 13 | Weatherproof glosses, pesticides |
Sources
- Wikimedia Commons Photo, Chlorothalonil
- Hazardous Substances Database entry for Chlorothalonil (Search term: 'chlorothalonil')
- IARC monograph summary, Volume 73 (1999) (PDF)
- INCHEM, Environmental Health Criteria 183: Chlorothalonil (1996)
- Health Canada (2010) Guidelines for Canadian Drinking Water
- Exposure Guidelines for Residential Indoor Air Quality (1987)(PDF)
- List of Maximum Residue Limits regulated under the Pest Control Products Act (PDF current as of June 2009)
- Health Canada’s Prioritization of the DSL (2006)
- CEPA List of Toxic Substances (1999)
- BC Ministry of the Environment, Survey of Pesticide Sales and Use in BC (1999) (PDF)
- BC Ministry of the Environment, Survey of Pesticide Use in BC (2003) (PDF)
- Ontario Ministry of Agriculture and Food, Survey of Pesticide Use in Ontario, 2003 (2004)
- Household Products Database (US)
- Syngenta Crop Protection Canada, Inc. Products: Fungicide: Bravo500 (2009)
- Natural Resources Canada, Common Pesticides Used in Forestry (2007)
- EXTOXNET: Extension Toxicology Network, Pesticide Information Profiles, Chlorothalonil (1996)
- Cox, C. (1997) ‘Fungicide Fact Sheet – Chlorothalonil’ Journal of Pesticide Reform, Vol. 17, No.4 (PDF)
- Health Canada, Total Diet Study, Whitehorse (1998)
- Health Canada, Concentrations (ppb) of pesticide residues in foods from Total Diet Study in Whitehorse, 1998
- The National Pollutant Release Inventory
Other Resources
- EPA, Integrated Risk Information System, Chlorothalonil (2008)
- Pesticide Info Sheet: Chlorothalonil, BC Ministry of Agriculture, Food and Fisheries (2004) (PDF)
- Health Canada, Pest Management Regulatory Agency PMRL2008-29, Proposed Maximum Residue Limit, Chlorothalonil (2008) (PDF)