The above chart shows the amounts of NPRI listed pollutants that Canadian companies report having released to the air, water or land or have injected into deep wells on their properties from 1995-1997 and the amounts they project through 2000. Because the number of sites reporting and the types of pollutants included in the inventory changes over time, there are two sets of figures. The All Data line represents total amounts. The Matched Data covers only figures on the same pollutants from the same sites over time, showing controls over time on a given range of pollutants.

Waste and consumption

Many of the substances that threaten human health are by-products of the manufacture of goods and chemical compounds. There is evidence that a lot of pollution could be eliminated through more efficient production that incorporates the real value of natural resources into system design — a process often called Natural Capitalism.

Inefficiencies in many production cycles not only produce dangerous pollutants, but waste valuable resources such as energy, raw materials and water. Producing goods in ways that maximize the efficient use of these materials would automatically reduce the amount of toxic substances released into air, water and soil thus making the production more economically and environmentally sustainable, and less dangerous to humans.

The economics of toxic substances

Some substances used to kill insects also kill other, valuable species and threaten humans. There is a trade-off between trying to increase food production and avoiding harm to human health, In the long run, the health and financial costs of using pesticides that accumulate in the food chain can be very high. The Ontario Farm Family Health Study suggests that people who use these chemicals in their work can experience negative health impacts within a few years or less of use.

One of the most studied pesticides is DDT, which was first registered for use in Canada in 1946. ( 1998, Chronology of organochlorine use and regulation in North America) Within a few years, scientists were finding DDT in birds' eggs, showing that the compound was accumulating in the food chain.

Rachel Carson was one of the first people to link poisons in the ecosystem with threats to human and animal health. Her writings about the dangers of DDT and other persistent pesticides, particularly her 1962 book, Silent Spring, helped trigger the modern environmental movement. Despite the evident risks of DDT, there were great economic, social and cultural pressures to keep using this cheap and effective insecticide.

After nearly a decade of scientific warnings, most uses of DDT in Canada and the United States were banned in the mid-1970s. Public awareness of the dangers of accumulating DDT also led to controls in a number of other nations. Because it is cheap, however, DDT is still widely used in many developing countries to control agricultural pests and malaria-bearing mosquitoes.

International efforts to control toxic chemicals

For years, nations have been wrestling with how to reduce or eliminate toxic substances that persist in the environment. Many of them travel across continents on wind and water currents or in the bodies of migrating birds. Negotiators have focused on what has been called the "dirty dozen." The Government of Canada has been very active in working to achieve an international agreement on these persistent organic pollutants (POPs).

The 12 pollutants targeted by negotiators are:

Aldrin	A pesticide applied to soils to kill termites, grasshoppers, corn rootworm and other insect pests, aldrin can also kill birds, fish, and humans
Chlordane	Used extensively to control termites and as a broad-spectrum insecticide on a range of agricultural crops, chlordane remains in the soil for a long time
DDT	An insecticide controlled in many nations, but still widely used in tropical countries, particularly to combat malaria. It builds up in the food chain, and has caused harm to wildlife, including thinning of eggshells
Dieldrin	Used principally to control termites and textile pests, dieldrin persists in soil. It is highly toxic to fish, aquatic animals and predatory birds
Dioxins	These chemicals are produced unintentionally due to incomplete combustion, as well during the manufacture of pesticides and other chlorinated substances. Some dioxins have been classed as possibly cancer causing. In test animals, they cause birth defects, cancer, immune system problems and disruptions in cell growth
Endrin	A chemical used against insects and rodents. It is highly toxic to fish
Furans	These compounds are produced unintentionally from many of the same processes that produce dioxins, and also during the production of PCBs. Like dioxins, furans are classified as possible human carcinogens
Heptachlor	Primarily used to kill soil insects and termites, this chemical is believed responsible for the decline of several wild bird populations. It also kills or causes reproductive problems in test animals
Hexachloro- benzene	HCB is used to kill fungi on some food crops. It is also a byproduct of the manufacture of certain industrial chemicals and exists as an impurity in several pesticide formulations. In high doses, HCB is lethal to some animals and, at lower levels, adversely affects their reproductive success. It interferes with enzymes that control the production of hemoglobin, a constituent of blood
Mirex	This is an extremely persistent chemical that was used as a fire retardant and a pesticide. It is toxic to a number of plants and animals, and is classified as a possible human carcinogen
Toxaphene	This insecticide is chemically similar to DDT. It is highly toxic to fish, and is classified as a possible human carcinogen
PCBs	This family of chemicals has been used widely in electrical, hydraulic and other equipment. PCBs were formerly used in many consumer products. They cause cancer in laboratory animal tests, and have been linked to health problems such as embryo mortality and deformities in wildlife

Missing Information
The Canadian Commissioner on Environment and Sustainable Development, in a May 1999 report, said that out of 22 OECD countries that answered a survey on pesticide use, only Canada and the Slovak Republic do not collect data on the sale of pesticides.