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Down-the-Drain Products and iSTREEM®: A Game-Changer in Evaluating Risk

Posted by Jenn Collins on May 10, 2021

While ecological risk assessment has focused on priority contaminants such as pesticides for decades, scientists and regulators around the world have had an increasing focus on the environmental impact of everyday chemicals found in home and personal care products and pharmaceuticals. These materials, along with a few others used indoors, constitute down-the-drain products.

Most of us probably don’t put much thought into our own, continuous contributions to down-the-drain materials. As a quick exercise, I made a list of my down-the-drain contributions just from this morning. First, hygiene products: toothpaste, mouthwash, shampoo, soap, conditioner, body lotion, deodorant, some plethora of skincare products, makeup, and hair products…then my daily vitamins and medication. I had a few extra minutes for chores this morning, so I needed to add dish soap, laundry detergent, and fabric softener. But wait, there’s more! Clothing in the washing machine can also contribute to down-the-drain exposure through the breakdown of synthetic fibers into nanoparticles and microplastics…so I need to add that to my list. That’s a pretty long list for an hour morning routine and it drives home an important point: most of what we use in our homes ends up going down-the-drain where, for those of us in cities, it is eventually transported to a municipal wastewater treatment plant (WWTP).   

After treatment, the effluent from WWTPs feeds into surface water bodies. Thankfully, we have tools like iSTREEM® to help us model the fate of these down-the-drain materials to ensure safety in our surface and drinking water. iSTREEM® is a publicly-available, web-based, spatially explicit model that estimates the concentration of a chemical that goes down-the-drain and the residual levels that subsequently enter the aquatic environment. Providing predicted environmental concentrations in effluent, receiving waters, and drinking water intakes, iSTREEM® is a critical tool beyond screening-level and used in higher-tier risk assessment of down-the-drain products.

iSTREEM® was originally developed decades ago by Procter & Gamble. Over the past 10 years, through a collaboration with the American Cleaning Institute, and Waterborne has been at the helm of the model’s development, testing, expansion, and outreach. In fact, iSTREEM® was named as one of the 20 most innovative and influential tools in 2013.

Waterborne’s iSTREEM® work, led by Raghu Vamshi, involves continuous evolution of the model and its application. Beyond its utility as an exposure assessment tool for conventional down-the-drain products in the U.S., we have employed modifications of iSTREEM® to investigate microplastics, veterinary medicines, pharmaceuticals, and artificial sweeteners. In addition, we actively engage in outreach activities of the model to encourage and support the user community.

In collaboration with Proctor & Gamble and American Cleaning Institute, we have officially expanded the iSTREEM® framework into a global model to cover China, Japan, Canada, Mexico, and more. This expansion was made possible by modern improvements in technology and computing power which allows us to efficiently integrate high-resolution datasets at a global scale. The current evolutionary step for iSTREEM® allows it application for exposure assessments of down-the-drain products not just in the U.S., but across the globe.

Visit istreem.org for the latest on iSTREEM® and stay tuned to our future newsletter for release of the publication describing iSTREEM global expansion and outreach activities!