The Madison Water Utility’s latest tests for toxic chemicals in drinking water found further indications the source of the hazardous material is the nearby Wisconsin Air National Guard base.
The tests looked for — and found — additional types of PFAS — synthetic chemicals linked to cancers and other serious health problems — that have been used in the military’s firefighting foam, the water utility said in a statement Tuesday.
“Because firefighting foams contain a mixture of PFAS compounds, we did expect to find some additional PFAS chemicals at low levels when testing was expanded,” said Joe Grande, the utility’s water quality manager.
Four additional types of PFAS were revealed to be in drinking water from Well 15 on East Washington Avenue. Each of the four was measured at just above the detection limit of 2 parts per trillion.
Meanwhile, two of the most common forms of the toxic chemical were found at levels roughly the same as in previous tests.
Tests analyzed at two labs averaged 11.4 parts per trillion, which is below a controversial 2016 U.S. Environmental Protection Agency health advisory of 70 parts per trillion for the two compounds, the water utility said.
The EPA advisory is controversial in part because it is up to five times too high to protect children, infants and fetuses, the federal government’s leading toxicology agency said last year.
In the Madison results released Tuesday, there was an increase in the total concentration for all the types of PFAS found, however there was some uncertainty about exactly how much was found, according to data from the water utility.
More than 3,000 types of PFAS have been synthesized for use in products such as nonstick pans, food wrappers, fabric protectors and firefighting foam.
They have been linked to a variety of serious health problems. The Wisconsin Air National Guard base on Madison’s North Side is the likely source of the drinking water contamination.
Because the National Guard hasn’t tested off the base, it’s difficult to know exactly where PFAS is spreading and when heavier concentrations may reach drinking water.
The water utility has begun monthly tests to help ensure that increased concentrations are noticed sooner rather than later.
Samples taken on Feb. 4 were sent to two labs. One lab checked for 30 types of PFAS compounds, while the other looked for 24. In tests going back to November 2017 when PFAS was detected at Well 15 near East Washington Avenue, there were efforts to find as many as 18 PFAS compounds.
In the latest tests, one lab found a combined 56 parts per trillion for 10 PFAS compounds it detected, but the results included caveats. There was an indication the reported 3 parts per trillion for one compound might not be valid, and the 2.9 parts per trillion for another compound was listed as approximate.
The total is higher than the combined 41.5 parts per trillion for six PFAS compounds from sampling done in October.
In the latest Madison drinking water results, the other lab reported 45 parts per trillion for eight compounds, but a portion of the measurement was considered approximate. Levels were listed as approximate for four of the compounds totaling 9.5 parts per trillion.
“Variability among labs is not uncommon, and it also reflects the absence of a standard method for PFAS testing,” Grande said. “We expect directly comparable results in the coming months because of consistency in the types PFAS compounds we’re testing for and the lab method used. Any trends will become more clear as monthly testing continues this year.”