Environmental Exposures and Cancer Risk

By Barrie McDowell

Between September 2008 and January 2009, an advisory panel set up within the National Cancer Institute look at the potential effects of environmental exposures on cancer in our community. The Panel consists of three members appointed by the US President, who by virtue of their training, experience, and background are exceptionally qualified to appraise the National Cancer Program. At least two members of the Panel are distinguished scientists or physicians.
This is the 240 pages report submitted in April 2010 by President’s Cancer Panel warning that “the true burden of environmentally induced cancers has been grossly underestimated” and urging steps be taken to reduce people’s broad exposure to carcinogens. It is worth the read for anyone who is interested in preventing cancer and in preserving the continuation of the human race. This report recommends several practices to reduce environmental exposure in our everyday lives. We highlight some of the points and issues raised in this report as we have already previously emphasised these in our book “Is Your Food Killing You?”
Research on environmental causes of cancer has been limited by low priority and inadequate funding and there is a lack of emphasis on environmental research as a route to primary cancer prevention, particularly compared with research emphases on genetic and molecular mechanisms in cancer. This report states that “Efforts to identify, quantify, and control environmental exposures that raise cancer risk, including both single agents and combinations of exposures, have been complicated by the use of different measures, exposure limits, assessment processes, and classification structures across agencies in the U.S. and among nations. In addition, efforts have been compromised by a lack of effective measurement methods and tools.” Current toxicity testing relies heavily on animal studies that utilize doses substantially higher than those likely to be encountered by humans and fails to take into account harmful effects that may occur only at very low doses especially to developing foetuses and during childhood. This category is more vulnerable than adults to increased cancer risk and other adverse effects from virtually all harmful environmental exposures. In addition, a potential agent is tested singly rather than in combination with other potential environmental agents making the results weak, flawed, or uncorroborated. Environmental carcinogens are everywhere; in our soil, air, water, and numerous consumer products.
Manufacturing and other industrial products and processes are responsible for a great many of the hazardous occupational and environmental exposures experienced by us. Many banned contaminants remain in our environment because of the slow decomposition. The report states that “Pesticides (insecticides, herbicides, and fungicides) approved for use by the U.S. Environmental Protection Agency (EPA) contain nearly 900 active ingredients, many of which are toxic. Many of the solvents, fillers, and other chemicals listed as inert ingredients on pesticide labels also are toxic, but are not required to be tested for their potential to cause chronic diseases such as cancer. It is overwhelming when you consider all the things that are or might be hazardous from our drinking water to cell phones to vaccines.
Women usually have higher levels of many toxic and hormone-disrupting substances than men. Some of these chemicals have been found in maternal blood, placental tissue, and breast milk samples from pregnant women and mothers who recently gave birth. Thus, chemical contaminants are being passed on to the next generation, both prenatally and during breastfeeding. Some chemicals indirectly increase cancer risk by contributing to immune and endocrine dysfunction that can influence the effect of carcinogens. Ideally both mothers and fathers should avoid exposure to endocrine disrupting chemicals and other possible carcinogens prior to the child’s conception and throughout pregnancy and early life.
The fact is, instead of using preventive methods towards these environmental agents, the governing bodies need incontrovertible evidences that these agents are a hazard before action to ameliorate it is initiated. By this time, the agent will have affected millions and what it has already done to our genetic makeup and to the survival of our future generations we can only speculate on.
Interestingly and not unsurprisingly, the panel’s assertions have been disputed by the American Cancer Society which argues that lifestyle factors like smoking, sun exposure, alcohol consumption, exercise and diet are the main causes of cancer. According to the National Cancer Institute, tobacco accounts for 29% to 31% of cancer deaths, diet for 20% to 50%, infectious disease for 10% to 20%, ionizing and ultraviolet light for 5% to 7%, occupational exposure for 2% to 4%, and pollution for 1% to 5%. Shelia Hoar Zahm, deputy director of cancer epidemiology and genetics at the National Cancer Institute notes, however, that these numbers are from a 1981 paper reviewing studies from the 1970s, which probably studied exposures dating back to the 1960s and earlier.
How could it be possible that governing health experts cannot agree what is causing cancer? Who should we believe? Is it possible that both are correct? After all, environmental toxins are in our diet and lifestyle. We eat convenience foods that has been processed with chemicals, high heat and irradiation and stripped of its nutritional value and instead contains carcinogenic compounds formed during the processing steps. We eat food that is high in the wrong kinds of fats; obtaining omega-3 fats from sources that are contaminated with mercury, polychlorinated biphenyls (PCBs) and dioxins; consuming olive oil that is exposed to heat and has lost its potential antioxidant properties; we eat fresh fruits and vegetables not in a synergistic way to prevent but to increase cancer etc. We are advised by our national health authorities to eat synthetically produces vitamins and food that has no proven benefit to our health, instead causing the opposite and increasing the risks of cancer. Lifestyle factors such as smoking and alcohol consumption are associated with socialising and the use of consumer products that contain potential toxins such as perfumes and toothpastes.
We feed our babies with milk that has been exposed to contaminated plastic such as from Bisphenol-A (BPA) bottles and give them food from jars due to our hectic (or lazy) lifestyles. We are so civilised that we have to come indoors without removing our shoes and use the same clothes indoors that we have been using outdoors, where exposure to certain types of hazardous agents are greater. It is diet and lifestyle that after all is causing cancer!