Pesticides more influential in causing cancer than previously thought

Mar 20 2006

New research at the University of Liverpool suggests that environmental contaminants, such as pesticides, are more influential in causing cancer than previously thought.

Previous studies in cancer causation have often concluded that exposure to carcinogenic or endocrine-disrupting chemicals, for example, organochlorines (OC) - found in pesticides and plastics - occurs at concentrations that are too low to be considered a major factor in cancerous disease. Now new research at the University of Liverpool, published in the Journal of Nutritional and Environmental Medicine, has found that exposure even to small amounts of these chemicals may result in an increased risk of developing cancer - particularly for infants and young adults.

The research consisted of systematic reviewing of recent studies and literature concerning the environment and cancer, and was supported by the Cancer Prevention and Education Society. Professor Vyvyan Howard and John Newby, from the University's Department of Human Anatomy and Cell Biology, also found that genetic variations, which can predispose some people to cancer, may interact with environmental contaminants and produce an enhanced effect.

Professor Howard said: "Organochlorines are persistent organic pollutants (POPs), which disperse over long distances and bioaccumulate in the food chain. For humans the main source of OC exposure is from diet, primarily through meat and dairy products. Children are exposed to dioxin, a by-product of OCs, through food; dioxin and other POPs can also cross the placenta and endanger babies in the womb. Breastfed infants can be exposed to OCs with endocrine disrupting properties that have accumulated in breast milk. Our research looks at involuntary exposure to these chemicals in the air, food and water.

"Environmental contaminants - in particular synthetic pesticides and organochlorines with hormone-disrupting properties - could be a major factor in causing hormone-dependent malignancies such as breast, testicular and prostate cancers. Preventative measures for these types of cancer have focused on educating the public about the danger of tobacco smoke, improving diet and promoting physical activity. We should now, however, be focusing on trying to reduce exposure to problematic chemicals."

The research team has also looked at anecdotal evidence, from practicing physicians in pre-industrial societies, which suggests that cancerous disease was rare amongst particular communities, such as the Canadian Inuits and Brazilian Indians. This suggests that cancer is a disease of industrialisation.

Professor Howard added: "The World Health Organisation estimates that between one and five percent of malignant disease in developed countries is attributed to environmental factors; but our research suggests this figure may have been underestimated."

Jamie Page, Chairman of Cancer Prevention and Education said: "This research is very important and suggests that there are links between chemicals and cancer. It is our opinion that if progress if to be made in the fight against cancer, far more attention and effort must be made to reduce human exposure to harmful chemicals."

Professor Howard's finding will be published in the Taylor & Francis Journal of Nutritional and Environmental Medicine and can be viewed at www.tandf.co.uk/journals/titles/13590847.asp