Kali Katerberg/Daily Mining Gazette Graduate student Emily Shaw speaks on her research covering contaminants in the Great Lakes and surrounding areas.

HOUGHTON — Contaminants in bodies of water create issues all around the world as they move up the food chain to humans.

Michigan Tech graduate student Emily Shaw spoke Monday on her research into poly-chlorinated biphenyls (PCBs), a major source of contamination in the Great Lakes Basin.

PCBs are man-made organic chemicals that were manufactured from 1929 to 1979 according to the EPA. Among uses were carbon-less copy paper and flame retardant, Shaw explained. PCBs are very resistant to degradation keeping them in the environment creating health risks and causing environmental damage.

PCBs are known carcinogens and can cause other non-lethal health issues.

“PCBs are accumulated and as you move up the food web they magnify,” Shaw explained.

Humans eating contaminated fish can get a large dose of these PCBs with continued consumption.

In the course of her work, she found a clear difference among fish species and an overlap in contamination between marked areas of concern and those that weren’t.

In areas of concern, carp toxicity levels exceeded EPA guidelines, as did walleye. Smallmouth bass were high in contaminants in areas that were not noted for concern.

“Different species assimilate PCBs differently that leads to differences in overall congener (a single PCB compound) body burdens but also toxicity,” Shaw explained.

With these findings in mind and EPA research, repeat consumption of PCB contaminated fish should be avoided.

“This is important when we look at it in context that toxicity can come from multiple food sources and if, for these species, they’re already over that guideline…including fish in your diet can push us over the overall limit,” Shaw said.

Following her research, Shaw sees a case for better monitoring of contaminated sites which may assist with understanding the effects of cleanup efforts.