We are what we eat: Scientists probe the potential effects of emerging contaminants

When contaminants get into the water system, some people might assume that standard water treatment techniques would make that water free from potential contamination.

The truth is, it is not that simple.

What happens when detergents, flavors, fragrances, hormones, medications, new pesticides, veterinary medicines, and other chemicals make their way into waterways of the Great Lakes Basin? Researchers are exploring these contaminants of emerging concern, or CECs, to help us better understand the potential impacts on wildlife and people.

For example, consider a commonly used over-the-counter pain reliever. Sunlight, temperature, pH or microbial activity will naturally break it down into different smaller compounds. Those smaller compounds, and the medication itself, are collectively termed “contaminants of emerging concern.”

Between the years of 2010 and 2014, our agency, the U.S Geologic Survey, and the Environmental Protection Agency (EPA) set out to characterize emerging contaminants present in Great Lakes Tributaries.  From 2015 to the present investigations have focused on assessing hazards and impacts these contaminants have on fish and wildlife species.

Daniel Gefell, biologist for the USFWS, holding a Bowfin at one of the sampling sites, USFWS.

Daniel Gefell, biologist for the USFWS, holding a Bowfin at one of the sampling sites, USFWS.

Funded by the Great Lakes Restoration Initiative, collaborators sampled water, sediment, and fish populations from a variety of different Great Lakes field sites. In New York, field efforts were primarily focused in the Rochester area and in the North Country in the St. Lawrence river drainage.

The most consistently studied organism is fish, with few studies directed toward the toxic effects in freshwater mussels, freshwater aquatic plants, or other native aquatic species. Four approaches were taken to evaluate fish populations and the effects of emerging contaminants.

1)         Biologists measured over 200 sampling sites and found that many of these emerging contaminants are consistently present in the water and sediment within the Great Lakes Tributaries.  From this information, biologists determined which chemicals are most often detected and at what levels so they could mimic environmental conditions with laboratory studies.

2)         In the same places where CECs were found, wild fish populations were evaluated for indicators of poor health including changes in physical appearance and reproductive health.

Drawing blood from a fish to send in for CEC analysis, USFWS.

Drawing blood from a fish to send in for CEC analysis, USFWS.

3)         Unexposed hatchery raised fish were caged and placed in the same areas where CECs were found and where wild fish were evaluated.  Hatchery fish were used because they were unexposed to CECs before the evaluation.  Biologists then compared hatchery fish to the wild fish to help determine the impacts of CECs on their health.

4)         Biologists looked at previous scientific publications of field and laboratory studies to take advantage of all the information we know about individual chemicals and their effects on fish. Biologists used the lab information to infer hazards to fish due to exposure of CECs.

So far, lab studies are confirming that many of the CECs have negative impacts on fish including mortality, developmental effects, and reduced reproductive capacity. Many studies have also confirmed that some CECs accumulate in fish.

Tumor on the mouth of a bullhead - Photo Credit Jo Ann Banda, USFWS.

Tumor on the mouth of a bullhead – Photo Credit Jo Ann Banda, USFWS.

What does it mean when other animals–or even people–eat those fish?

Not enough information is known yet to say for sure how eating fish living in a CEC rich environment could impact humans, but a study published in 2015 evaluated a large group of northeastern bats to determine if CECs could be found within those bat populations.

Have you ever heard of the phrase “you are what you eat”? That’s essentially what’s happening here.

Northeastern bats have a high metabolism, meaning they have to eat a lot of food! The bats are eating bugs, which may have lived in contaminated environments. In turn, eating a lot of insects could mean they have a higher likelihood of exposure to chemicals in the environment. The bugs are incorporating the contaminants into themselves from eating or living with exposure to these contaminants, and when the bats eat the bugs, the contaminants within the bugs are being incorporated into bat tissues.

The results of the 2015 study showed that CECs could be detected within the bats themselves. The CECs detected most frequently in samples were PBDEs (compounds used in flame retardants), salicylic acid, thiabendazole(a fungicide), and caffeine. Other compounds detected in at least 15% of bat samples were digoxigenin, ibuprofen, warfarin, penicillin V, testosterone, and N,N-diethyl-meta-toluamide (DEET), all of which are commonly used.

How do these contaminants make their way to bats? Well, we have some clues. When we dispose of household or personal items, or apply substances to our properties, they can make their way to streams. Insects accumulate them because they live in those areas, and then the bats feed on the insects.

Many of the CECs we are most concerned about were made to be biologically active in the human body (i.e. medications) and we know they work well because they made it into the marketplace. That information coupled with the fact that we know very little about the broader scope of CECs, besides lab studies, is troubling.

What this means for human health….we don’t know. A large number of people get their drinking water from the Great Lakes. Emerging contaminants have been found in some Great Lakes drinking water supplies.

These are complicated issues that warrant deeper exploration to determine the potential human and environmental health impacts as well as ways to help prevent the continued contamination of our environment.

We live in a world where these types of far-reaching health concerns have become prominent in our day to day lives. It is a stark reminder of the finite resources our world possesses and that the actions we take greatly impact not only our direct health and well-being, but the global health of all who inhabit the earth.

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