People should not eat livers from white-tailed deer harvested within about 5 miles of a contaminated Johnson Controls/Tyco Fire Products facility in Marinette, according to an advisory issued Tuesday by state health and natural resources officials.
The recommendation is based on testing that found elevated levels of perfluorooctane sulfonate (PFOS) in liver tissue of all 20 deer sampled near the industrial site.
The findings suggest “eating liver from deer in this area is likely to result in significant PFAS exposure,” according to the Wisconsin Department of Natural Resources.
PFOS is one of a family of dozens of per- and polyfluoroalkyl compounds known collectively as PFAS. The chemicals are used in industrial processes and manufactured goods, including firefighting foam.
The contaminants enter the environment through accidental spills of PFAS-containing materials, discharges of PFAS-containing wastewater to treatment plants and certain types of firefighting foams.
Epidemiology studies suggest some PFAS are associated with increased risk of pregnancy-induced hypertension, liver damage, thyroid disease, asthma, decreased fertility, some cancers and a decline in response to vaccines.
The environment in and around the Tyco facility, which manufactured firefighting foam, is known to have a high level of PFAS and is one of more than 40 Wisconsin sites being monitored for the contaminants by the DNR.
Sometimes called “forever chemicals,” PFAS don’t break down in nature and are being increasingly detected in water, soil, humans and animals.
In 2018, Michigan became the first state to issue a “do not eat” deer advisory due to PFAS. It found a level of 547 parts per billion PFOS in muscle tissue of one deer killed near the former Wurtsmith Air Force Base in northeastern Lower Michigan. The advisory remains in place for a small area around the retired base.
The Wisconsin study of PFAS in deer in Marinette began due to “high interest from the community,” according to the DNR.
For the investigation, 20 deer were killed in February at the JCI/Tyco Fire Technology Center in Marinette. Samples of muscle, heart and liver tissues from each deer were tested for 26 types of PFAS at the Wisconsin State Laboratory of Hygiene.
All 20 deer had a detectable level of PFOS in their liver tissue, ranging from 3.83 to 92 parts per billion. Eleven of the 20 had PFOS in excess of 10 parts per billion.
Across the samples, six types of PFAS (8:2 FTA, PFDA, PFHxS, PFNA, PFOS and PFUnA) were detected in the livers. One deer — a 2-year-old male — had all six, according to the DNR report.
Two deer had detectable levels of PFOS (2.29 and 3.07 ppb) in heart tissue, and one had PFOS (2.67 ppb) in muscle.
Since the liver functions as the body’s filter for contaminants, the finding of more PFAS in liver than muscle and heart tissue samples was expected by researchers who reviewed the study.
For comparison purposes, muscle samples from 13 hunter-killed deer in Price County were tested; no PFAS was detected in any of the animals, according to the DNR.
Although public health advisories regarding PFAS are relatively few and emerging, the Wisconsin DNR recommends restricting consumption of fish that have PFOS levels in excess of 10 ppb.
Since only one deer in Marinette had a detectible level of PFOS in its muscle tissue, and it was below the threshold for the agency’s fish advisory, the DNR opted to limit the “do not eat” recommendation to livers.
“We want to be clear that people should feel comfortable eating venison from deer they’ve harvested near this area,” said Tami Ryan, DNR wildlife health section chief.
A spokesman for Johnson Controls said he respected the DNR’s cautionary advice, but also noted officials in Michigan have set the action level for PFOS at 300 ppb.
“Deer hunting and love of the outdoors are important to our community and way of life,” said Fraser Engerman, Johnson Controls director of global media relations. “The safety of our community always comes first.”
Engerman said science and methods related to PFAS was still being understood and his company looked forward to continuing its work with the DNR “to help put the best practices in this new area of research to work.”
The DNR’s Ryan said 20 deer from other spots in Wisconsin would be tested for PFAS later this year.
The agency will hold two Zoom sessions Wednesday for people interested in learning more about the Marinette deer liver advisory or PFAS studies in the area.
The online sessions are scheduled from noon to 2 p.m. and from 6 to 7:30 p.m. No preregistration is required. Visit dnr.wi.gov for more information.