A Bay Journal article (2019-06-17) reported on the potential threat microplastics pose to both the Chesapeake Bay and water treatment plants. The article noted that while the Chesapeake Bay Program has classified microplastics as a contaminant of mounting concern, researchers are still do not know the full environmental and health risks they can pose.

Microplastics are very small pieces of plastic (often 5 millimeters or less in size) that now found throughout the Bay and its tributaries. Often broken down from larger plastic litter, microplastics enter the aquatic foodchain after being “eaten” by single-cell organisms that think it is food. The plastics then work their way up the aquatic foodchain and end up in fish and ultimately people.

The article noted that the Bay Program Scientific and Technical Advisory Committee held a workshop to assess the threat. From the article:

“We might have an idea of the exposure, but on the effect side, we’re not so sure,” said Jerry Diamond, an ecotoxicology and risk management expert with the consulting firm Tetra Tech, at the outset the meeting.

“With a chemical, we can say that this concentration of copper has this effect, so if you have this much in the water it’s not good,” Diamond said. “For microplastics, we don’t have that.” …

At the workshop, a consensus emerged that more work is needed to measure not just the presence but also the potential harm that microplastics cause when they’re prevalent in the region’s habitats, the bellies of fish and shellfish, and even drinking water.

The article summarized current research surrounding microplastics, including:

• Microplastics are found throughout the Bay and its tributaries but are more prevalent in surface waters near urban and suburban areas after heavy rainfall
• Transport of microplastics in waters needs further study (i.e., how far can microplastics travel from a source and where are there significant sources)
• Other contaminants and harmful chemicals can bind to microplastics, potentially increasing their concentration
• Microplastics can carry harmful bacteria and pathogens
• Microplastics have been shown to harm the development of some aquatic species, decrease immune responses, and increase stress

Workshop attendees stressed the importance of establishing a baseline as to what constitutes a harmful concentration of microplastics. Another important area of study is the increasing presence of microplastics in drinking water. From the article:

Water treatment processes may come into play too, as scientists learn more about the presence of microplastics in drinking water. The Hampton Roads Sanitation District is working with the Virginia Institute of Marine Science to understand what types of microplastics might be making it through the plant’s treatment process. That question seems more urgent now that the plant is infusing some of its processed water back into the aquifer, where it could become a drinking water source for the future.