Return to the list
Canada - Final Regulatory Action
DDT CAS number:
Date circular:

Chemical name: 1,1'-(2,2,2-trichloroethylidene)bis[4-chloro-benzene]

Final regulatory action has been taken for the category: Industrial

Final regulatory action: The chemical is Severely Restricted

Use or uses prohibited by the final regulatory action:

The Regulations prohibit the manufacture, use, sale, offer for sale or import of DDT, or a mixture or product containing DDT, unless the substance is incidentally present.
DDT was first registered as a pesticide in the 1940s, and although it was never manufactured in Canada, it was widely used in pest control products to control vector-transmitted diseases like malaria, as well as insects in forestry and agricultural applications. DDT was widely used during World War II to protect soldiers and civilians from malaria, typhus and other diseases spread by insects. In response to increasing environmental and safety concerns, most uses of DDT in Canada were phased out by the mid-1970s. Registration of all uses of DDT was discontinued in 1985, with the understanding that existing stocks would be sold, used or disposed of by December 31, 1990.
DDT remains a very useful pesticide for vector control in countries endemic for infectious diseases such as malaria, dengue, lymphatic filariasis.
There have been no known industrial uses.

Use or uses that remain allowed:

The Regulations do not apply to DDT that is:
contained in a hazardous waste, hazardous recyclable material or non-hazardous waste;
contained in a control product (i.e., pesticide);
present as a contaminant in a chemical feedstock used in a process from which there are no releases of the substance and provided that the substance is destroyed or completely converted in that process to a substance that is not listed in Schedule 1 or 2 of the Regulations; or
used in a laboratory for analysis; in scientific research; or as a laboratory analytical standard.
The Regulations also establish a permit system that provides a mechanism for temporarily exempting certain applications of a substance listed in the Regulations. A permit may be granted only if the Minister of the Environment is satisfied that there is no technically or economically feasible alternative or substitute available for the substance. In addition, the Minister must be satisfied that measures have been taken to minimize or eliminate any harmful effects of the substance on the environment and human health. Finally, the applicant must provide an implementation plan that identifies specific timelines for eliminating the substance. Each permit lasts for 12 months, and can be renewed only twice.

The final regulatory action was based on a risk or hazard evaluation: Yes

Summary of the final regulatory action:

The Prohibition of Certain Toxic Substances Regulations, 2005 prohibits the manufacture, use, sale, offer for sale and import of toxic industrial substances listed in Schedules 1 and 2 to the Regulations. DDT is found on Schedule 1, which lists substances subject to total prohibition, with the exception of incidental presence. Note: The prohibition of DDT under the Regulations applies only to non-pesticide uses; pesticide uses are prohibited under the Pest Control Products Act.

The reasons for the final regulatory action were relevant to: Environment

Summary of known hazards and risks to the environment:

DDT was assessed against the criteria for selection of Track 1 substances under the federal Toxic Substances Management Policy (TSMP) in the 1990s. This policy provides a management framework based on two key objectives: virtual elimination from the environment of toxic substances that are persistent, bioaccumulative, and result primarily from human activity (Track 1); and life-cycle management of other toxic substances and substances of concern to prevent or minimize their release into the environment (Track 2). The criteria for the selection of substances for Track 1 is provided in Table 1 (attached). The Ministers of the Environment and of Health used a summary of a review of the physical, chemical and toxicity properties to justify a decision that DDT meets the criteria for management as a Track 1 substance under this policy.
Predominantly Anthropogenic
Although the generation of DDT and its metabolites by natural processes cannot be excluded, such contributions to the total existing levels in the environment are considered negligible. The analysis of sediment core samples reveals that DDT and its metabolites were not detectable in Lake Ontario prior to the 1940s, and peaked in the late 1950s and early 1960s. This demonstrates that the concentrations of DDT and its metabolites in environmental media are related to the production and dispersive use of this insecticide. On the basis of the available information, it was concluded that the concentration of DDT in the environment is due largely to the quantities used or released as a result of human activity.
Air: DDT may evaporate during and following its application. DDT in air exposed to sunlight will be subject to both direct photolysis and photo-oxidation. Photo-oxidation half-life estimates range from 17.7 hours to 7.4 days. DDT adsorbed onto particulate matter in the atmosphere is ultimately deposited by precipitation and dustfall. Long-range transport of DDT to the Arctic is well documented. DDT has been detected in Arctic air, soil, snow and ice and virtually all levels of the arctic food chain.
Soil: Half-life measurements under field conditions for the aerobic degradation of DDT in soil range from 2 years to greater than 15 years. In flooded soils or under anaerobic conditions, the biodegradation is faster, with half-life estimated from 16 to 100 days, and the metabolite residue is DDD. DDD is highly persistent in soils, sediments and water, with half-lives estimated as high as 190 years.
Water: Direct photolysis in aqueous media is very slow with an estimated half-life of 150 years. Indirect photolysis half-lives are affected by natural substances in water. Substances such as humic acids increase the degradation rate of DDT, the observed half-life in natural waters being lower than that measured in distilled water. Half-life estimates for photo-oxidation in natural waters range from 7 to 350 days. The half-life for the hydrolysis of DDT in water is estimated to be 22 years.
Sediment: Using sediment cores from Lake Ontario, half-lives of DDT in sediments of 14 to 21 years have been estimated by plotting the ratio of DDT to its anaerobic breakdown product DDD over time. Many studies indicate that bottom sediments in lakes and rivers act as reservoirs for DDT and its metabolites.
On the basis of the available information, it was concluded that DDT is persistent in air, water, soil and sediment.
Bioconcentration factors (BCFs) for DDT have been calculated in both aquatic and terrestrial organisms. Whole organism BCFs up to 13,880 have been reported in bacteria, 58,100 in marine algae, and 84,000 in freshwater marsh plants. The invertebrate Mytilus sp. has shown BCFs of as high as 690,000. Aquatic vertebrates such as fathead minnow and rainbow trout have demonstrated BCFs up to 154,100 and 51,355, respectively. The reported log Kow for DDT range from 6.2 to 7.48. On the basis of available information, it was concluded that DDT is a bioaccumulative substance.
In response to environmental and human health concerns, Canada and other countries have taken initiatives to manage DDT. On the basis of the available considerations, it was concluded that DDT is equivalent to toxic under the Canadian Environmental Protection Act.

Expected effect of the final regulatory action in relation to the environment:

DDT is not used, sold, produced, imported or exported in Canada. The Regulations ensure that DDT is not introduced into industrial applications in the Canadian market, which could represent an increase in risk to Canadians' health and the health of the environment. The Regulations will also assist Canada in meeting its international obligations respecting DDT under the Stockholm Convention on Persistent Organic Pollutants (POPs).

Date of entry into force of the final regulatory action: 15/05/2005