For too many years, municipalities, industry, and communities have relied on the properties of large bodies of water to diffuse persistent pollutants to below detectable levels. Now new research shows that dilution, which never was an environmentally acceptable solution to pollution, may not even behave as expected. Researchers from the University of Wisconsin have found much larger than expected concentrations of pollutants from personal care products as far as 3.2 km from shore. The concentrations away from the shore were identified as presenting a medium or high risk to the environmental health of the lake ecosystem. The researchers conclude their report:

The most frequently detected PPCPs [Pharmaceuticals and personal care products] were metformin [an antidiabetic drug], caffeine, sulfamethoxazole [an antibiotic], and triclosan [an antibacterial]. Given the widespread detection of PPCPs, these pollutants are not ephemeral and pose an environmental risk to the sixth largest lake in the world. Therefore, high dilution is not adequate to mitigate the risk from this cocktail of PPCPs and the potential ecological risk for large lake systems is much higher than previously understood.

The fact that many of the environmentally toxic substances used in PPCPs [in the case of caffeine, used in many beverages and not fully metabolized by the body] find their way through sewage treatment plants and out into the aquatic environment is by no means a new finding. The fact that these chemicals are not adequately diluted, if there is such a thing as adequate dilution, is adding to our body of knowledge. It can only be a matter of time before the public begins to consider the pollution of lakes as large as Michigan with toxic substances to be socially and environmentally unacceptable.

Industry will almost certainly be fingered as the transgressor. Governments will likely step in to regulate the use of common aquatic contaminants. Municipalities will seek money from PPCP manufacturers and brandowners to pay for sewage treatment plant upgrades to remove these substances from effluent discharges. Environmental groups will point fingers at what they consider to be the most polluting products.

In the case of polyethylene microspheres, some companies have shown that they can play a leadership role in removing the potentially harmful ingredients from their products (see, for example, http://www.unilever.com/sustainable-living/Respondingtostakeholderconcerns/microplastics/) It seems to GallonDaily that companies could benefit, by avoiding regulations, sewer levies, and criticism, if they worked more aggressively and more openly to remove these additional persistent environmental contaminants from their consumer products or, where removal may not be possible, as in the case of drugs, to inform consumers as to less environmentally harmful ways to use and dispose of the product.

A full list of the substances identified in Lake Michigan, their concentrations, the test methodology, and much more information is available in the paper published in the Elsevier journal Chemosphere at http://www.sciencedirect.com/science/article/pii/S0045653513010412