Cancer is commonly linked to toxic chemicals, and although the overall incidence of cancer is not high, the deadliness of the disease means it gets a lot of media attention. The EPA considers an “acceptable” cancer risk from man-made pollution to be one additional cancer case for every 100,000 people. Yet this is nothing more than an unenforced suggestion; many chemical exposures vastly exceed this level, and little or nothing is done about it. Even at this “acceptable” rate of 1 extra cancer per 100,000 people, this would add up to approximately 3,100 additional cancer cases just in the U.S. alone. Now consider that some chemicals are linked to increased cancer risks that are 20 to 50 times this amount, and multiply this number by the tens of thousands of potentially cancer-causing chemicals our there (each of which is allowed to create its own “acceptable” cancer risk), and you start to see the potential scope of this problem.
A 2010 report published by the President’s Cancer Panel by Dr. LaSalle Leffall Jr. and Margaret Kripke, M.D., stated that it’s known that at least 6% of all cancers are environmentally caused, but warned that the actual number could be much higher. (O’Callighan, 2010) As a general rule, most experts believe that around half of all cancer cases are attributable to toxic chemicals, and a few extremists even assert that cancer is almost exclusively a problem of toxic exposures. Such an extremist view is unlikely; it’s known that viruses cause around 20% of cancer cases, and random, cancerous DNA mutations no doubt occur on their own. Yet it’s safe to say that a sizeable chunk of cancer cases (maybe even the majority) are linked to toxic exposures.
Cancer Causing Chemicals
Asbestos, cigarette smoke and air pollution all show strong links to cancer. A more moderate cancer risk is posed by arsenic, atrazine, DDT, dioxin, and bisphenol-A, all of which have been found to disrupt gene expression in a way that might lead to cancer. Referring to the research on 20 or so common synthetic chemicals, Tami Gouveia-Vigeant and Joel Tickner (2003) note that “The vast majority of those studies show direct links to cancer, or increased susceptibility across almost every body system.” If you extrapolate these findings across all the chemicals we don’t have adequate data on, it’s safe to say that most chemicals are probably linked to some small increase in cancer risk.
How do chemicals cause cancer?
Chemicals can be linked to cancer in two ways. First, the chemical itself can cause cells to turn cancerous by causing mutations in the cell that lead to a malignant growth. (Refer to our eBook section on genetic changes from chemicals for more information on how this happens.) A number of chemicals have been shown to cause cancerous mutations in cell cultures.
Chemicals may also increase cancer in an indirect way – not by causing cells themselves to turn cancerous but by affecting the body in a way that makes cancerous growths more likely. For example, there’s a heated debate over whether organophosphates lead to cancer. Although they don’t produce cancerous cells in a petri dish, they have been linked to lowered levels of a cancer suppressing hormone and an impaired immune system, both of which could lead to increased rates of cancer, even if the chemical agent itself isn’t what causes the cancer.
Or consider the fact that many breast cancers are fueled by estrogen. This hormone is produced in fat tissue, one of the reasons that obese people have higher rates of the disease. By logical reasoning, this would suggest that estrogen mimics such as BPA could increase cancer risks, which is indeed what we see in animal studies.
Just as with any health issue, there are many variables that can tilt the scale in one direction or another. As Myss and Shealy state, “Even carcinogenic agents (chemicals that seem to induce cancerous changes in cells) are inadequate in and of themselves to produce the disease unless there are co-factors.” (1993, p. 327) Such co-factors can include things like stress, diet, living conditions, and other illnesses a person may be battling at the time.
The link between chemicals & childhood cancer
As previously stated, it’s believed that children accumulate as much as half of their lifetime cancer risk by age two as a result of early chemical exposure. (EPA, 2005) The Environmental Protection Agency estimates that children are about 10-times more vulnerable to cancer-causing chemicals on average, and that chemicals which cause cancer by directly interfering with DNA are approximately 65-times more potent for infants and toddlers than those same chemicals are for adults.
Philip and Alice Shabecoff observe that “In two generations, from 1950 to 2001 – from the boomers’ childhood to their children’s – the rate of childhood cancers of all types leapt 67.1 percent, exceeding rates among adults. The United States has the fourth-highest incidence of childhood cancer in the world. Since the 1970s, when tracking such data became reliable, brain cancer among children has increased about 35 percent and acute lymphocytic leukemia over 47%. …The highest rates for all childhood cancers are for the years 2001 and 2005, and it’s thought the trend will continue.” (2010, p. 36)
A recent study by the University of Texas found that those living within 2 miles of the Houston Ship Channel (which exposed them to butadiene, among other chemicals) had a 56% higher risk for childhood leukemia than those living 10 miles away. (Morrison, Heath & Jervis, 2008) Deirdre Imus, founder of the Deirdre Imus Environmental Center for Pediatric Oncology, believes recent increases in pediatric cancers are largely due to the poor environmental quality of our homes.
“Almost all childhood leukemia’s and many other childhood cancers begin before birth, so we have to look at the exposures of the mother and even the father,” says Dr. Martyn Smith. He adds that it usually requires at least two events to set the stage in motion, both before birth and after. “A virus could start the disease, then a chemical in the environment might make the disease worse. Or the other way around.” (Shabecoff & Shabecoff, 2010, p. 99)
Proving the link between chemicals & cancer
Because of the variables involved, it isn’t always easy to link specific chemicals to specific cancer outbreaks. Cancer clusters certainly occur by chance, just as when you flip a coin you will often get several heads or several tales in a row merely by chance. The fact that cluster patterns occur by chance has given cover to polluters, who can dismiss chemically induced breakouts as a random fluctuation. The problem, however, is that not every cancer cluster is the result of random variation, and distinguishing the chemically caused ones from the natural chance clusters is almost impossible.
The closest anyone’s ever come has been the cancer cluster that broke out in Woburn, Massachusetts, in which 21 children had died of cancer by 1986 in an area served by two well pumps that were known to be toxic. Decades later, two hydrogeologists, Dr. E. Scott Bair and Maura Methany, one of his graduate students, used modern computers to piece together a model that calculated more than 100,000 different variables – a feat that was impossible with the technology that existed back then. When they ran this simulation, the kids who died of cancer had been precisely those whose mothers drank the most polluted water while pregnant. (Bair, 1997)
Yet another after-the-fact study came to a similar conclusion, finding that “The risk of leukemia significantly increased as the amount of contaminated water from wells G and H delivered to the households increased.” It was also found that once the two contaminated wells were shut down, the incidence of childhood leukemia also all but went away, and the area now has an incidence of childhood leukemia lower than the national average. (Costas et al., 2002; Shabecoff & Shabecoff, 2010, p. 119)
So although we may not be able to link specific chemicals with specific cancer cases, we know without a doubt that toxic chemicals are playing a significant role in cancers of all types, and especially childhood cancers.