The scientific research that describes the impact of pesticides on wildlife suggests that pesticides affect reproduction, growth, neurological development, behaviour and the functioning of the immune systems (Canadian Environmental Law Association, Draft, 2000).

While these studies have generally been done on animals exposed to higher concentrations than those to which humans are in fact exposed, the experts use their findings to extrapolate effects on humans since it is difficult, even impossible to demonstrate what effects pesticides have on human beings. The wildlife toxicity data has shown that the young (at pre- and post-natal stages of growth) tend to exhibit greater sensitivity to pesticides, and that pesticide effects may manifest themselves later in life and may even be transmitted from generation to generation.


Acute and Chronic Effects
From: The Standing Committee on Environment and Sustainable Development, House of Commons, Canada

Exposure to pesticides can cause acute or chronic effects on health. Acute (or short-term) effects generally occur immediately after heavy exposure to pesticides, and are well-documented. Work by Dr. Pierre Mineau, a researcher with Environment Canada's Canadian Wildlife Service, has shown that an insecticide can kill instantly. Some insecticides used in granular form, such as carbofuran and terbufos, are highly toxic to birds that ingest them as dietary grit. Dr. Mineau told the Committee that a single granule of carbofuran52 can be instantly lethal to a small bird. For terbufos, the kill rate is about 50% (Evidence, Meeting No. 12, December 2, 1999).

A chronic effect develops over a long period of time, and may last for several years after initial exposure. The effect may be related to long-term or repeated exposure to a pesticide at a low dosage, or to exposure to a high dosage for a short time. Chronic health effects typically include cancer, interference with the development of the fetus and child, and disruption of the reproductive, endocrine, immune and/or central nervous systems (neurotoxic effects) (Butterfield and Rosenberg, 1998, Gilbertson, 1998, Chance and Harmsen, 1998, Pernille et al., 1998). There is controversy surrounding the identification of many chronic effects of pesticide exposure, because of inconsistencies in the research, contradictions among existing studies, and because of data gaps. It is difficult, therefore, to demonstrate a conclusive link between pesticides and certain illnesses, as was pointed out to the Committee by Dr. Kelly Martin of the Canadian Association of Physicians for the Environment:

Despite the confounding factors in these studies, the witness believes that the potential for serious impact on human health is cause for concern. While the evidence may be limited, the hypotheses developed by the scientific community are of sufficient concern that they warrant further investigation. Dr. Martin added:

Dr. Merryl Hammond, founder of Action Chelsea for the Respect of the Environment also expressed her concerns to the Committee:

Butterfield, M. and D. Rosenberg, Exposure: Environmental Links to Breast Cancer, film screening, Ottawa, October 1998; Gilbertson, M., Linking Water Quality to Wildlife and Human Health," Focus, International Joint Commission, November 1998, p.18-19; Chance, G.W. and E. Harmsen, "Children are Different: Environmental Contaminants and Child Health," Canadian Public Health Review, Volume 89, Supplement 1, May/June 1998, p. 10-14; Pernille, A., Grandjean, P., Jorgensen, T., Brock, J.W., and H.B. Hartvig, "Organochlorine exposure and risk of breast cancer," Lancet, 352(9143), 1998, p. 1816-1820.

The potential effects of the main chemical groups of pesticides are described in:

Potential Effects of Pesticides on Health


Vulnerable Groups
From: The Standing Committee on Environment and Sustainable Development, House of Commons, Canada


   1.  Children

   2.  Females, People in Poor Health, People Who Work with Pesticides, and Residents of the North

CCA Lumber (Pressure Treated Wood)

CCA lumber has been the center of a storm that has grown from a whisper to a roar over the past year.

The concern is over the wood’s rot and insect resistant properties achieved from the preservative CCA, which is chromated copper arsenate, a pesticide. Two of the ingredients of CCA are arsenic and chromium, both on the U.S. government’s Top 20 Hazardous Substances list.

Concerns over health risks from the use of this pressure treated lumber have sparked a voluntary phase out of this product by industry. The reason, according to manufacturers, was “market pressure”. And the reason for the market pressure is arsenic and its threat to human health.

Pressure treated lumber is the greenish wood frequently used for decks, play sets, picnic tables, docks, boardwalks, surrounding people’s gardens, and many other uses.

The National Academy of Sciences and the National Research Council in the U.S. have produced seven reports on arsenic, concluding multiple times that it causes a range of cancers including lung, bladder and skin cancer in humans. In 2001, a new National Science Council study concluded that health risks from arsenic are greater than previously assumed.

Another new study released by the Environmental Working Group and the University of North Carolina-Asheville, warns that arsenic used to treat wood products doesn’t dissipate with time and that children who play on decade-old equipment are as likely to be exposed to high levels of the potential cancer-causing agent as are those who play on structures manufactured recently. Using wipe tests from 263 decks, play sets, picnic tables, and sandboxes in 45 states, researchers found arsenic levels on wood surfaces remain high for 20 years. Children who rub their hands on a tiny surface area of new or old playground equipment have a one-in-ten chance of coming into contact with 10 times as much arsenic as the EPA drinking water standard allows.

The disposal of CCA wood also poses a problem of huge proportions. There is no effective way to dispose of it because arsenic never breaks down.

CCA wood has been banned in Switzerland, Japan, and Indonesia and its use is restricted in Germany, Denmark and Sweden.

An option for consumers is to substitute less toxic alternatives for pressure treated wood. Consumers can effectively use naturally rot-resistant woods, including larch (also known as tamarack), hemlock, juniper, redwood, and cedar.

Arsenic Treated Wood precautions:

• Do not burn treated wood indoors or outdoors: the smoke and ash are very toxic.

• Do not put treated wood in your mouth

• Do not let children chew or lick treated wood

• Do not use treated wood for wood chips, mulch or compost

• Do not use treated wood for cutting boards or counter tops or anywhere it has direct contact with food

• Do not use treated wood to store food or animal food

• Do not use treated wood for bee hives

• Do not let treated wood come into contact with drinking water

• Do not grow edible plants near treated wood

• Do not let children or pets play under treated decks or stairs

• Do not use CCA treated wood or wood products in construction projects where children can come in direct contact with the material

• If a CCA structure burns, precautions should be taken to avoid the fumes, and extreme precautions should be used in dealing with the ash.

If you have existing structures made of CCA wood:

Sealing surfaces with polyurethane oil-based stains will slow arsenic leaching and reduce skin contact. Resealing should be done every year or two and more often for high friction areas. Water based sealants DO NOT prevent leaching of arsenic. Don’t use products that may chip or peel and need scraping and sanding before recoating. Scraping or sanding may dislodge more arsenic.

• If you must Work with CCA Wood:

• Don’t work with treated wood indoors.

• Saw the wood outdoors. Do not inhale sawdust from treated wood. Wear eye protection, a mask and rubber or leather gloves.

• Do not allow sawdust to collect on the ground.

• Wash exposed skin areas thoroughly after working with the wood.

• If sawdust gets on your clothes wash them separately.