your backyard for an afternoon of cutting the grass, you'll probably be slathering on some sunscreen before you go.

We know that the sun's powerful rays are responsible for most cases of malignant melanoma, the most deadly form of skin cancer, and for years we have been told how to protect ourselves from this deadly disease. However, sun exposure may not be the root of all skin cancer.

With the help of funding from the Canadian Institutes of Health Research (CIHR), Dr. Richard Gallagher at the British Columbia Cancer Research Centre is trying to determine if there may be another environmental trigger for the disease. "There have been clues from previous studies suggesting that people who handled a lot of organochlorines in their jobs have an elevated risk of melanoma," explains Dr. Gallagher.

Organochlorines are a large group of chemicals including pesticides such as DDT, aldrin and mirex and the coolants known as polychlorinated biphenyls (PCBs).

In the 1970s, many governments phase out the use of DDT, PCBs and other organochlorines when researchers discovered that the chemicals had negative effects on the environment and human health."Organochlorines are still an issue because they are so persistent in the environment," says Dr. Gallagher "They bio-accumulate in the bodies of humans and other animals, so organochlorines from the '70s are still out there."

Dr. Gallagher is heading a research project that will help determine whether or not these toxins cause malignant melanoma. He and his team are comparing the levels of various organochlorines in the blood of melanoma patients to the levels in people without the disease. Patients in the study will also fill out detailed questionnaires on their history of sun exposure so that Dr. Gallagher can try to separate the effects of the chemicals from the effects of sunlight, something that previous studies have not done.

The study's findings may someday help doctors determine a patient's risk of developing melanoma, and may also help researchers and policy makers assess the safety of other
pesticides and industrial chemicals. However, Dr. Gallagher cautions that this is a preliminary study and any findings will have to be validated with further research.

"We don't want to give people the impression that this is a big issue before we've actually confirmed that there is a connection between organochlorines and melanoma," says Dr. Gallagher.

"If you are concerned about developing melanoma, your best bet is to avoid exposing your
skin to too much sun."