Avis Antel

The Canadian Cancer Society recently hosted a two-day conference* to provide a forum for the discussion of research, policies, and practices surrounding agricultural and other non-cosmetic uses of pesticides. This was in response to a wide range of opinion about pesticides, from calculations of risk/benefit in the scientific literature to questions about protection for human health and the environment. Cosmetic-pesticide restrictions are in place in Quebec, Ontario and many towns and cities but what about farms? Participants and speakers included North American and European scientists, physicians, and farmers, as well as representatives from groups like BCAM and the chemical/pesticide industries.

Initial presenters supported the continued regulated use of pesticides, citing evidence that most pesticides are non-carcinogenic; the challenge is to isolate those that are carcinogenic. They also believe that pesticide residue in the blood is so far below the level considered unsafe that it poses no real threat – although one speaker did present data showing that levels of residue are even lower in the blood of children eating organically-grown fruits and vegetables. Moreover, the newer forms of pesticide, unlike older versions, are said to biodegrade very quickly. Of particular interest to BCAM, recent studies of the organochlorine insecticides, despite being known endocrine disruptors and xenoestrogens, apparently do not lead to an increased risk of breast cancer. (This flies in the face of an Ontario study which found that women who work on farms have about three times the breast cancer risk of those not on farms.**)

A subsequent speaker described epidemiological studies in California exploring the relationship between proximity to and/or higher use of pesticides and increased rates of childhood cancer.

Childhood exposure to carcinogens may increase susceptibility to cancer for persons choosing certain occupations in later life, but exposure to hormone disruptors may be more dangerous than carcinogens. According to the IARC (International Agency for Research on Cancer), children’s risk of cancer may not manifest itself until adulthood as the ‘windows of exposure’ vary depending on the individual’s physiological development. An attendee warned that hormone disruptors cause the “sin” of the mother to be visited on her children and grandchildren. He also commented that the use of non-cosmetic pesticides is highly regulated and that we should be more concerned about the unregulated ingredients in personal care products and off-label use of medicines.

Epidemiological evidence is not the same as evidence of carcinogenic activity. Regulators view epidemiological evidence much like circumstantial evidence in court. It is able to suggest associations but doesn’t provide proof the chemical caused the disease. One speaker stressed the difficulty of establishing cause and effect, warning us that relationships that seem obvious are not always what they appear. As an example he cited a tongue-in-cheek article published in an epidemiology journal which showed a significant correlation between fluctuations in the stork population and out-of-hospital deliveries!

The presenters on the first day challenged the use the precautionary principle as a basis for regulations governing the use of non-cosmetic pesticides. There are many different definitions of the principle, making it less valid as a viable standard; it is based on risk but regulations are based on hazard and hazard is not equivalent to risk. One interesting comment was that the precautionary principle is a fallback position to cover situations where there is insufficient data to make an informed decision, and most pesticides are so highly regulated that this principle does not apply.

During the second day of the conference, we heard from speakers who took positions more allied to that of BCAM. The European countries seem to be much further ahead of Canada and the U.S. in searching for ways to reduce exposure to pesticide contaminants through organizations like CEHAPE (Children’s Environment and Health Action Plan for Europe) and HEAL (Health and Environment Alliance). These organizations use precautionary-based policies and practices.

CEHAPE has regional priorities: a commitment to a reduction in mortality and morbidity, to safe secure human settlements, a reduction in respiratory diseases due to indoor and outdoor pollution, and a reduction in risks of disease and disability arising from exposure to hazardous chemicals, physical and biological agents, and hazardous working environments.

HEAL’s mission is to monitor health concerns and evidence and to stimulate the broader health community’s understanding and participation. Its priorities are environment and health, safe use of chemicals (e.g., REACH, or Registration, Evaluation, Authorisation & restriction of CHemicals), climate change, reductions in indoor and outdoor air pollution, as well as sustainable development, public participation, and safe urban environments.

The presentations on pesticide use on farms stressed that applications and handling influence level of risk. Occupational Health and Safety regulations stress the safest non-cosmetic use of pesticides, including required information about the pesticide, the training of the user, the possibility of substituting other pesticides where possible, control of drift, and strict rules about timing of pesticide use.

From the point-of-view of the farmer, pesticides are part of the system although their use can be reduced through knowledge and the use of alternatives — which also may be questionable in terms of health and safety. Where do we draw the line? As one speaker noted, 40,000 Americans are killed every year in car accidents but no one thinks about banning cars.

Farm income and expenses are important factors when considering use of pesticides — farmers need to produce as much as possible for as little as possible. Currently, less than 2% of Canadians are involved in primary agriculture, an industry that needs to compete globally. Pesticides are expensive and generally used sparingly and often as a last resort. Ironically, the attempt to control costs can result in uncertified de facto organic farming when pesticide use is reduced or eliminated to cut costs.

Can organic farming feed the world? The principles of organic farming are: to protect the environment, to maintain soil fertility, to recycle resources, to promote the health and safety of livestock, to ensure product integrity, and to offer local produce. The regulatory framework for organic farming is strict but certification as organic means only that the farming is organic, not that the product is.

The conference concluded with the hope that meetings such as this will stimulate more research and more discussion, and that we will soon have better evidence of a conclusive link between health and a clean environment.

* ‘Exploring the Connection: A State of the Science Conference on Pesticides and Cancer’, November 12-13, 2008, Marriott Yorkville Bloor Hotel, Toronto, Ontario

** Brophy, JT, Keith MM, Gorey KM et al “Occupation & Breast Cancer: A Canadian Case-Control Study” Ann NY Acad Sci, 1076:765-777 (2006). (See also “Cancer society turns sights to farm pesticides” by Martin Mittelstaedt, Globe & Mail, Nov. 12, 2008)