As has been frequently noted in prior posts, toxic torts are all about causation. Whenever a plaintiff alleges a particular type of disease or injury, alternatives need to be evaluated. This is especially so in the world of chemical exposure since many diseases or injuries can derive from a multitude of different chemicals or even some nonchemical conditions (e.g., the make-up of the bacterial population in one's gut may have a major influence on the cause of a variety of diseases). Two more have now entered the fray.
First is our old friend, ethyl alcohol (booze, beer, wine, the hard stuff). Even moderate alcohol use may substantially raise the risk of dying from cancer, according to a new study that offers the first update in decades regarding alcohol-related cancer deaths. Researchers examined seven types of cancers known to be linked to alcohol use: cancers of the mouth and pharynx, larynx, esophagus, liver, colon, rectum, and female breast. To link the cancer to alcohol use, they relied on surveys of more than 220,000 adults, 2009 U.S. mortality data, and sales data on alcohol consumption. Alcohol is tied to 3.2 to 3.7% of all U.S. cancer deaths.
Breast cancer accounted for the most common alcohol-related cancer deaths among women, contributing to 15 percent of all breast-cancer deaths. Among men, cancers of the mouth, pharynx, larynx and esophagus accounted for the most alcohol-linked cancer deaths.
Critics note that the study did not account for the style of drinking (consuming small amounts over time vs. occasional binge drinking); the critics note that binge drinking has the stronger association. The study's authors note that alcohol can have health benefits (e.g., coronary related disease), but they still assert that alcohol causes 10 times as many deaths as it prevents. They also note that there is no safe threshold for alcohol and cancer risk.
The study can be found at: http://ajph.aphapublications.org/doi/abs/10.2105/AJPH.2012.301199.
The second casual factor is hair dye. What is interesting is the number of steps necessary to trigger the causative agent. Hair dyes contain secondary amines (see http://en.wikipedia.org/wiki/Amine) that are capable of forming potentially carcinogenic nitrosamine derivatives (http://en.wikipedia.org/wiki/Nitrosamine) when exposed to atmospheric pollution. The authors point to numerous scientific articles that confirm the existence of secondary amines in hair dyes (and their intermediates), the possibility of nitrosation by atmospheric NOx of secondary amines to give the N-nitrosamines, and the significant safety risks on N-nitrosamines.
In humans nitrosamines are believed to be causative agents for gastic cancer. [Some tobacco specific nitrosamines are causative agents of lung cancer.] One study of rubber workers found that exposure to high concentrations of nitrosamines is associated with increased mortality from cancers of the oesophagus, oral cavity, and pharynx, but not with increased mortality from cancers of the stomach or lung. See http://oem.bmj.com/content/57/3/180.full. Nitrosamines are also present in many cosmetics, resulting from impurities in various ingredients.
The study can be found at: http://www.mdpi.com/1996-1944/6/2/517.
Thus, in alleged cancer cases, drinking patterns of and the use of cosmetics by the plaintiff may be a key issue to be explored when examining alternative causal explanations.