Precaution and Triclosan
The other day I was pointed to an article by Cass Sunstein in the Boston Globe online, about the precautionary principle. I agree with Dr. Sunstein that fundamentally the precautionary principle is incoherent as a risk management tool, at least in the way a lot of the “deep green” people view it. All policy choices entail risks of some form; these may be disparate risks that fall differentially across the population, but we risk making irrational decisions if we don’t try to wrestle with them. Some of his examples are pretty dim, but then again he’s writing for the general audience, who is pretty dim when it comes to making decisions where uncertainty is involved.
In most or nearly all cases where risks are being assessed, you’ll be making a decision based on incomplete information. It may not be prudent to allot the time or resources to do the studies to more fully assess a risk before deciding to act on it. Indeed, the call for more study has become a strategy used by some corporations for deferring action on controlling health risks associated with their products, or with chemical substances that their workers are exposed to. It’s effective too, because, like the general audience, nearly all policy makers are genuinely bad dealing with environmental decisions under uncertainty.
There’s a “strong” version of the precautionary principle, which in effect is to take action to stop something that poses a significant risk until you prove it’s safe. That’s a recipe for either precipitous action or inaction, with Dr. Sunstein’s favorite example being invading Iraq. The more reasonable version of the principle suggests that a lack of decisive evidence of harm should not be grounds for not taking action. For example, the 1992 Rio Declaration, setting out principles for sustainable development, states, "Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation" (see Principle 15).
Of course, matters become more difficult to resolve in practice. A good example is antibacterial soaps containing triclosan. Soaps containing triclosan were no more effective than plain soap at preventing infectious illness symptoms and reducing bacterial levels on the hands. Also, several laboratory studies demonstrated evidence of triclosan-adapted cross-resistance to antibiotics among different species of bacteria. The conclusion of a recent review was:
The lack of an additional health benefit associated with the use of triclosan-containing consumer soaps over regular soap, coupled with laboratory data demonstrating a potential risk of selecting for drug resistance, warrants further evaluation by governmental regulators regarding antibacterial product claims and advertising. Further studies of this issue are encouraged.
Triclosan is used extensively in consumer products, including personal care products, textiles, and plastic kitchenware. The triclosan molecule has some structural similarities to phenols, diphenylethers and polychlorinated biphenyls (PCBs). It is widespread in low levels in waterways throughout the U.S., and has the potential for bioaccumulation in the environment. Biological monitoring performed by the CDC in 2003 and 2004 has detected triclosan in 75 percent of the urine samples collected from a representative sample of the U.S. population. In other words, traces of triclosan are detectable in a large number of people. Finally, triclosan was recently screened using mammalian cell lines for endocrine disrupting potential, and yes, there’s a possibility it’s an endocrine disruptor (potentially interfering with cell signaling that occurs in brain, heart and other cells, according to the UC Davis researchers).
Antibacterial soaps and consumer products have been identified as risk factors for antibiotic resistance. Infections from Methicillin-resistant Staphylococcus Aureus (MRSA) are becoming a growing concern for hospitals and healthcare professionals. Recommendations for managing MRSA in the community aren’t calling yet for getting rid of soaps and products containing triclosan. Noone is calling triclosan a threat to human reproduction yet (for example, CERHR isn’t investigating it).
However, it does raise the question of when action is warranted to reduce exposure to triclosan. There’s limited evidence that it isn’t terribly effective as an antibacterial agent in consumer products, and may contribute to antibiotic resistance. It’s widespread in the environment, bioaccumulative, detectable in humans, and now has emerging evidence of subtle adverse effects that might affect future generations. Absolutely nothing conclusive about any of it, but with the currently regulatory framework and political environment, it could involve decades of study and deliberation before a decision is made that widespread use of triclosan poses a risk or not. Then, if the determination is yes, it poses a risk, several more years would be required before it’s out of the product distribution chain.
This seems like a perfect application for the precautionary principle. However, until the precautionary principle develops some intellectual rigor, and possibly a quantitative framework, it’s going to remain a nice idea without a lot of decision-making punch.
Labels: endocrine disruptors, environmental health policy, precautionary principle, triclosan