"Environmental agencies are often quick to declare the air, water and soil safe after chemical disasters like the Ohio train derailment — but huge knowledge gaps exist."
"Shortly after entering the field of public health in the early 1970s, Stephen Lester learned there was one thing he should steer clear of studying: how exposure to multiple chemicals at once might be devastating human health.
It was nearly impossible to secure government grant money for mixture studies, due to monumental hurdles in interpreting the results and ultimately determining which chemicals might have caused any documented health issue. If, for example, you exposed a rat in a lab to seven chemicals and the rat developed cancer, you could conclude the mixture causes cancer but are no closer to being able to say which toxin or combination of toxins was responsible. Researchers didn’t bother submitting grant applications to do such work.
Little has changed in the 50 years since. Few mixture studies receive funding, and very little data on the effect of chemical mixtures exists. And when disasters strike, scientists assess risk the way they’ve been doing it for decades: one chemical at a time — even though the reality is that people are often exposed to a cocktail of different chemicals."
Advertisement 
