Could traditional food resource consumption put tribal communities at greater PFAS risks?

Gavin Dehnert of Wisconsin Sea Grant at the University of Wisconsin Madison was asked by the Voigt Intertribal Task Force to come look at contaminants found in the liver of several wolves found by the task force. This started some research into looking at more traditional food sources consumed by Native Americans and also looking at PFAS contaminants through a “One Health” lens rather than looking individually at environmental health, human health and wildlife health. Dehnert said the research conducted showed varying bioaccumulation of PFAS compounds in various plants, animals and even water. He said research could be informed by the amounts of compounds that were found in these environments and how those amounts changed within one environment, and that this could only be done using a more holistic approach. His research found that exposure was not evenly distributed and, in many Native cultures and tribal communities that rely on more traditional foods, it seems that there may be increased risks in ares with higher PFAS contamination.

He presented his research at the Great Lakes PFAS Summit recently. He said his goal was to look at trees, fish and water, sediment and aquatic plants. He began his presentation talking about maple sap and maple syrup. He wanted to know if PFAS had an impact on maple sugar bushes and if the variation in harvest practices.

In general, the research showed there was little difference in PFAS levels that were dependent on collection methods. Buckets, sap bag and more Western style tubing systems were used, Dehnert said, and there seemed to be no difference in PFAS levels based on different methods.

PFAS was found in seven of the 10 samples in his study, he said. Most of the levels of PFAS found from these very rural samples, Dehnert found, were relatively low. Only two short-chain PFAS were found, PFBA and PFPeA, which Dehnert said made sense, as short-chain PFAS has a higher solubility in water and would be easily taken up by sugar bushes.

The next question was what the difference might be when sap was made into syrup. Because it takes 40 gallons of sap to make one gallon of syrup, he wondered whether concentrations would increase or whether there would be evaporation that might remove some of the PFAS. Researchers were able to test three maple syrup samples, and found the concentrations in the syrup to be 25-30 times higher compared to the sap. 

Denhert said he was no longer just seeing the two short-chain PFAS, however. Ten types of PFAS were detected in all of the different samples. In the end, he said, PFAS could be found in both sap and syrup.

“We can listen to sugar bush trees and let nature tell the story,” he said.

He also wanted to look at what aquatic environments could tell researchers about PFAS. He concentrated specifically on lakes in the Ceded Territory with high tribal harvest. He looked at spearing declarations and took recommendations from the Task Force to narrow the research down to 60 lakes from the over 600 lakes in the Ceded Territory.

The good news was that not all lakes in the study had elevated levels of PFAS. However, a few did. He said that water could be used to understand contamination quickly and provide immediate knowledge for tribal harvest.

Wild Rice Reservoir was one of the lakes in the study with relatively high levels of PFAS. Samples from various parts of the lake showed consistent levels of PFAS, no matter where the samples came from. Sediment samples from those same areas, however, had a much more widely different PFAS levels. Not only were PFAS levels in sediment different from place to place in the lake, but the types of PFAS found differed as well.

“What we’re finding in water is not always what we’re finding in sediment,” he said. “Sediment is also more spot specific.”

Dehnert then wondered what those differences in sediment could mean for plant uptake in those areas. He looked at wild rice, or manoomin, as well as arrowhead, also known as duck potato. Not only are arrowhead bulbs edible, but presence of the plants can be an indicator for wild rice habitat. 

His research found that PFAS in soils around arrowhead were much higher than in water in the same area. However, he found no PFAS detected in the roots of leaves of the arrowhead. In general, he said, it seemed aquatic plants had less uptake of PFAS than terrestrial plants.

Dehnert then turned to fish, looking specifically at walleye, yellow perch and northern pike. He detected PFAS in all fish in the Wild Rice Reservoir, with PFOS being the dominant PFAS found. What was more important, he said, was that levels were not much different from northern and walleye, with both having relatively high levels that would put them close to, if not into “do not eat” levels.

His research also found that in the Turtle Flowage, where PFAS levels were lower in general, bioconcentration did not seem to be a factor in fish. However, bioconcentration was a factor in the Wild Rice Reservoir. More PFAS was found in walleyes there than in the water.

“Maybe what fish are telling us is that not all lakes with PFOS are going to have PFOS levels high in fish,” he said, positing that there is perhaps some threshold where that is the case. He noted that not all fish were the same, and not all lakes were the same. In general, more sampling and more research was needed to netter understand how PFOS is moving through the environment. 

Dehnert said the research may conclude that tribal guidelines may not be in line with state guidelines, especially where Tribal harvesting and consumption includes much more fish and other harvestable goods from the lakes.

While guidelines have been created for consumables such as fish, none exist for consumables such as maple syrup, wild rice and arrowhead. Even terrestrial consumables such as cranberries, mushrooms and others that are foraged from the land have not been studied enough to create those consumption guidelines. 

“We want to make sure that these tribes are still going out, still harvesting food, still practicing their treaty rights, so how do we play that balance between protecting human health, but as well as protecting treaty rights?” Dehnert said.

He reminded that everything is interconnected. Where PFAS is in the environment, it is not just impacting humans. It is also impacting the environment, animals and plants in that environment. He called for researchers to collaborate and look at the problem from a variety of angles.

Beckie Gaskill may be reached via email at [email protected].