U.S laws promote this sort of unscientific behavior. As a result of such widespread abuses of the scientific method, many Americans have begun to lose confidence in science as a way of knowing about the world. When science is disconnected from the typical regulatory process, it openly acknowledges uncertainty. Then there is true uncertainty, which is an event with unknown probability. The effect of such combined exposures on your immune system is simply unknown.
Most environmental problems involve true uncertainty.
This, too, erodes people's confidence in science as a way of knowing. It is therefore vague and difficult to craft into workable policies. Likewise, the principle that the polluter should pay is often not useful in the real world because it is not obvious how much the polluter should pay, or when. Now some innovative thinking has come along to improve the situation. In recent years Robert Costanza, an economist at University of Maryland, has been exploring ways to improve environmental decision-making under conditions of uncertainty.