Q: Dow says that they do a lot to understand the possible hazards of their products. But all of their tests are conducted on single chemicals, when everyone knows we’re exposed to a sea of chemicals — mixtures of chemicals — every day. Aren’t these mixtures more dangerous than the single chemicals?

A: Dow actively conducts and supports research to understand the possibility of additional or increased danger introduced with exposure to a mixture of chemicals — that is, the issues of additivity and synergy of chemicals.

An additive effect is the interaction of two or more chemical substances that has a combined effect equal to the sum of the effects of each substance alone.

A synergistic effect results from two or more chemical substances acting in such a way that the total effect is even greater than the sum of the effects of the individual substances.

Alternatively, an antagonistic effect suggests an interaction between substances that results in a combined effect that is less than the sum of the effects of each substance alone.

People are exposed to extreme mixtures of chemicals as a part of their everyday lives and usually tolerate them well. For example, the food we eat currently consists of an assortment of fruits, vegetables, meats — which, taken together contain a mixture of hundreds of chemicals, including many natural toxins. Furthermore, people take multiple drugs for various ailments — an extremely common scenario especially in the elderly — yet drug interactions are relatively rare. It should be emphasized, however, that drug interactions are very different from environmental exposures because the drugs are given at high doses intended to cause changes in the body.

Dow considers it unlikely that the trace levels of chemicals we encounter in our ambient environment will cause adverse effects on our health.