Environmental Carcinogenesis -- Separating Fact From Fiction

One can hardly read a newspaper, turn on the radio or a television station, or surf the Internet without finding a myriad of information concerning yet another physical, chemical, or biological agent in our environment that can 'cause cancer' or, at least, lead to some one of another of a myriad of health effects that can affect our lives. Furthermore, we are also assaulted on television with as 'middle-of-the night infomercials' touting various natural or human made products that can benefit our health, or 'protect' us against a predisposition to cancer or other ailments, or guard us against exposure/attack in some undefined way from toxic materials and/or carcinogens. Most often, rather than being helpful (and maybe even accurate) this onslaught of information results in unmitigated confusion (at best) and very likely fear and/or false hope, and maybe even bad decision-making, for many.

This challenge of understanding 'real risk' vs. 'perceived risk' from natural or human-made chemical or physical agents present in our modern environment is not new. In 1962, for example, Rachel Carson's lyrical, yet as many believe, scientifically flawed, book Silent Spring was released. The book argued eloquently, but perhaps in much too broad strokes and, at times, erroneously, that pesticides, especially DDT, were poisoning both wildlife and the general environment while simultaneously seriously endangering human health. The large and significant emotional public reaction to Silent Spring launched the modern environmental movement -- which was very important and should be applauded. DDT itself became the prime target of a growing anti-chemical and anti-pesticide movement during the 1960s. Unfortunately, DDT toxicity and/or carcinogenicity data was never reasonably established and 'off-hand' commentaries alluding to things such as profound bleeding occurring in a man spraying DDT were never scientifically validated. Furthermore, reasoned scientific discussion and sound data not just on toxicity of DDT itself, but also on the balance of potential unfavorable effects vs. the favorable human health effects of DDT (ridding large population areas from vector-associated diseases) were brushed aside.

Basically, a fully integrated, in-depth risk/benefit analysis never took place, and 'effective dose metrics' integrated with an ecological impact at a host of levels of exposure were lacking. In the end, moving from DDT to other measures of mosquito control took time and in the interim period (between DDT removal from use and the development of alternatives) untold millions of lives were lost worldwide to diseases such as Malaria, Dengue Fever, Rift Valley Fever, and Yellow Fever.

A more-recent (but less deadly) example of understanding 'real vs. perceived' risk in the 'modern world' might be cooking with microwaves. Humans have been heating meals for thousands of years using fire, hot water and/or steam from hot springs (or boiling water in pots on over a fire), or merely cooking on hot rocks heated by the sun. Microwaving food is a relatively new process, having been introduced only in the last several decades. "Nuking" a pizza, or leftover food, is a quick and easy way to get a hot meal and not necessarily burn the roof of your mouth. As one might suspect, a host of 'human health' concerns have been raised over the use of microwaves in our modern kitchens (concerns ranging from electromagnetic radiation exposures to significantly overheating foods.

But is using a microwave worse for you than firing up the oven or, perhaps, using lighter fluid saturated charcoal? Well, a number of national and international organizations have judged that microwave ovens, when properly used, are indeed safe and appropriate modern cooking (ignoring the taste of the cuisine).

Moreover, from an environmental standpoint, a microwave oven is ecologically sound in that it uses much less electricity than a conventional oven, and there is no need for combustible petroleum products to 'start the fire.' In fact, microwaving meat can actually significantly reduce carcinogens over conventional heating, including such serious human carcinogens such as Heterocyclic amines and Polycyclic aromatic hydrocarbons, chemicals formed when muscle meat (beef, pork, fish, and poultry) is cooked using high-temperature methods, such as pan frying or grilling directly over an open or charcoal-fueled flame.

In reality, one could make a sound argument for a 'risk' with just about anything. In essence, risk is not universally the same for everyone in every situation, and these examples are merely representative of issues in which perceived 'risk vs. 'reality' may be at odds with one another relative to human perceptions as well as 'exposures' to environmental agents.

Overall, good risk assessment can only be made with accurate and validated information. The scientific community must play the key role in helping the public understand complex science issues. For example, scientists may differ with one another over the interpretation of research outcomes (based upon their own data or the interpretation of the data of others) and hold differing opinions about big scientific questions (i.e., Global Warming, Drug Risk/Benefits, Environmentally-associated cancers, etc). Such debates are important and necessary to help to fully understand the total data available, to anticipate and perform confirming experiments, and ultimately lead to a scientific community-based final assessment. But when spurious statements are pulled out of context and broadly disseminated, the result can me disinformation and resultant difficult and poor decision-making.

On a Global scale, the World Health Organization (WHO), located in Geneva, Switzerland, plays a significant role in this community-based final assessment. WHO is the 'Health Arm' of the United Nations and a specialized agency that concentrates exclusively on health by providing technical cooperation among countries, carrying out programs to control and eradicate disease, and focused on improving the quality of human life worldwide.

An important arm of WHO is the International Agency for Research on Cancer (IARC), which plays a key role in helping the world community understand 'fact from fiction' relative to human risk from exposure to carcinogens. Emphasis is placed on elucidating the role of environmental and lifestyle risk factors and studying their interplay with genetic background in population-based studies and appropriate experimental models. This emphasis reflects the understanding that most cancers are, directly or indirectly, linked to environmental factors and thus preventable. The IARC Monographs and Working Group Reports Programs are core elements of the Agency's portfolio of activities, with international experts working collaboratively to elucidate all evidence of the carcinogenicity (or lack of carcinogenicity) of specific environmental chemical or biological insults. The Agency is also committed to studying approaches for the early detection of cancer and in evaluating prevention strategies.

An example of the importance of IARC can be found in a recently published report stating that the air many of us breathe poses serious health risks. Thus, 'Air Pollution' (indeed a highly complex mixture) is a now officially a carcinogen, and there are no caveats about the new classification. This report comes came out, by chance, simultaneously with recent news that air pollution in China has virtually shut down some cities in that country because of noxious air quality and incipient health risk.

Air pollution is known to precipitously increase the risk of bladder cancer and, obviously, lung cancer, as well as contributing to heart disease and a myriad of respiratory ailments. The IARC report indicated that polluted air is about as carcinogenic as high concentrations of second-hand cigarette smoke (before you scoff this off as minimal exposure imagine sitting in a thick, smoke-filled room 24/7 for months at a time). This is a global problem well beyond China, but people in developing countries with large populations and booming manufacturing sectors with few pollution controls are particularly at risk. The same might be said for smog-cloaked US cities when complex with temperature inversions (hence the frequent 'smog alerts' that occur in some cities). It is inevitable that as pollution levels climb, so will the rate of cancer, the WHO said, and as a result IARC has identified air pollution as the worst, and most widespread global environmental carcinogen.

I have been a part of several IARC Working Groups and can confirm that the process is arduous and thorough, and significant debate occurs before and during the meetings of experts before a report is 'signed off' and made public. The group as a whole makes a decision, stakes their collective scientific reputations on that decision, and the report is then released for public consumption (for a list of reports see here).
Reports of this type from IARC (and other comparable groups within the U.S. and other nations) are key to helping the public understand 'risk' and providing significant professional judgment on controversial topics involving public health.

So, before accepting as 'truth' something overheard in a conversation, or from a 30-second snippet on TV or the radio, or culled from undocumented sources from the Internet, it is always best to take a 'step back' and 'consider the source' and try to understand if the information you have has been 'vetted/adjudicated' in some manner or is merely an 'opinion' shared.