Last month the US National Institutes of Health (NIH) and other collaborating agencies announced that they are using a new robotic system to study the toxicity of 10,000 chemicals that are currently used in consumer products, personal care products, food additives, pharmaceuticals and other industrial products.
The first question that springs to mind from this report is why are there so many chemicals that need to be tested for toxicity?
The sheer numbers dramatically illustrate the gap between industry's capacity to innovate with new chemicals and the capacity to verify their safety for human health and the environment.
But this is not the whole story: some of this toxicity testing backlog results from the fact that the very definition of "toxic" has been gradually changing as new discoveries are made in environmental health. In fact, the 10,000 chemicals under study by the NIH are actually only the tip of the iceberg of all of the chemical compounds in commerce today.
Depending on the precise chemical and which hormone it interferes with, endocrine disruptors can lead to a number of surprising effects, such as interfering with the maturation of adult animals or changing the male to female sex ratio in animal populations.
This leads to a new type of toxicity – the individual animals may not actually be sick at all, but it is clear that the population is unhealthy, because reproductive success is likely to be lower when adults do not properly mature or there are lower numbers of one sex than there should be. As a result, an entire species could crash without any individual ever being apparently sick.