Which causes cancer?
1. Wood dust from cutting and shaping lumber. 2. Tamoxifen, the anti-cancer drug. 3. Ethylene oxide, a gas used to sterilize medical instruments. 4. Ordinary sunlight.
All of the above appear in the 2003 edition of the bible for people who sometimes wonder, “What the heck, does everything cause cancer?”
The answer is a firm, “no.”
But 228 things definitely do, including some eyebrow-raisers like wood dust, the estrogen drugs used in hormone replacement therapy (HRT) and birth control pills, ordinary daylight, industrial chemicals that are mainstays in production of many consumer products, and even life-saving prescription drugs.
They all appear in the federal government's official list of known “carcinogens,” things that cause cancer.
Under a federal law, the National Toxicology Program (NTP) prepares the list and updates it every two years. NTP is part of the National Institute of Environmental Health Sciences, which is one of the National Institutes of Health.
Scientists actually nominate substances for the list. Expert panels of government and non-government scientists review the evidence and decide whether to list a substance. NTP then publishes its Report on Carcinogens, now in its 10th edition. It can be read and printed without charge at http://ehp.niehs.nih.gov/roc/toc10.html.
The report makes a distinction between “known” human carcinogens, and “reasonably anticipated” carcinogens.
A substance gets in the first category when there's plenty of evidence of its cancer-causing nature from studies in people. It goes into the “suspect carcinogen” group when the strongest evidence is from tests in laboratory animals.
Listing affects how substances are labeled, handled, and used - especially in workplace settings where people often face the highest exposure.
The report is a bonanza of accurate, dispassionate information for individuals concerned about the chemicals they encounter in the workplace, at home, or even while pursuing hobbies like woodworking.
For instance, it describes the how and why of wood dust's status as a carcinogen, new on the list this year, in a way that may encourage woodworkers and carpenters to wear those dust masks or respirators regularly.
The Report on Carcinogens, however, may be one of the most misunderstood and misused of all technical government science documents.
It does not detail the seriousness of a substance's cancer risk, for instance, or put the risk in perspective by thoroughly discussing benefits of certain listed substances that may far outweigh the risks.
That goes for medications like tamoxifen, which have good effects that far outweigh the bad. Tamoxifen saves lives from breast cancer. But is also increases the risk of a less-serious and more treatable cancer of the lining of the uterus.
Environmental groups sometimes cite a substance's listing in the report as evidence that it poses a serious threat to people in their everyday lives. Listing alone does not mean a substance poses such a threat, the report clearly states.
In fact, the threat may be tiny or nonexistent for people who get little exposure.