Over the last decade, biological research has thrown up so many surprises that conventional medical wisdom is turned repeatedly on its head. One such instance happened last week, when the French National Institute of Health and Medical Research published a paper saying safe levels of pollution are not really safe in the long term. It is not that there is anything wrong with the limits set by regulators. It is that the combined effect of many pollutants at safe levels can be harmful in the long run.
This finding, which does not seem startling when stated, actually has the potential to revolutionise toxicology, or the science of toxic chemicals. A safe dose is a basic concept in toxicology, based on which regulators set limits of exposure. If there is no safe dose, all our current toxicity regulations have to be discarded. Setting new norms wouldn’t be easy either, because no one would know what limits to set for each pollutant, and a zero limit is an impossible target to achieve for many pollutants. This would worry all those who want to remain healthy and take the trouble to maintain a healthy lifestyle.
There seems to be no real way of completely avoiding pollution in this world. As scientists have found out now, pollutants can enter our body in low doses — even if we wash and peel and cook our food — through what we eat and cause many metabolic diseases. We also know now that air pollution can clog our arteries in the long run. So it doesn’t matter if you eat healthy, exercise well, sleep soundly and avoid stress; your environment can give you Type II diabetes or heart disease.
For some time, a few toxicologists have been arguing against the concept of a safe dose of a pollutant. Frederick vom Saal, professor at the University of Missouri, has been campaigning against this concept when applied to endocrine disruptors. These are chemicals that mimic natural hormones and thus disrupt their function. Vom Saal has published research that shows toxic effects, particularly to foetuses, at extraordinarily low doses of exposure of some endocrine disruptors. The most common is Bisphenol A, or BPA, one of the most widely used chemicals in the world. There is no way anybody can avoid BPA exposure at the moment.
Virtual Models
Vom Saal’s work is controversial, and some toxicologists do not accept his thesis. But now it turns out that his ideas can be extended to other pollutants as well. If seemingly harmless drugs can combine in the body to produce deadly effects, there is no reason to suppose that pollutants cannot have similar effects. We are surrounded by automobile and coal plant exhausts, pesticides, plastics, arsenic and lead in water, nanoparticles and probably hundreds of thousands of other chemicals that we do not see or know about.
It is a riot of pollutants. Every year, chemists synthesise hundreds of new chemicals that did not exist before. Of course they are in low doses, but they are manufactured in larger volumes when found to be useful. Currently there is no regulation that requires each of these chemicals to be tested for human health impact before release into the environment.
Such studies are also impractical and will slow down progress, if not create an impossible situation for the chemical industry. Virtual testing can make a difference, when adopted at some point over the decade. Till our virtual models improve, we could clean up the obvious pollutants. A country with sick people has no future.
