A University of Maine computer scientist is leading an effort to develop an interactive online tool to help government regulators and the general public monitor forever chemical hotspots across the country and help identify what places should be tested next.

Torsten Hahmann, an associate professor of spatial computing, wanted to find a way to combine and analyze the growing body of evidence from scientists and government agencies investigating PFAS, otherwise known as per and poly-fluoroalkyl substances, in hopes of providing a comprehensive view of a national problem.

“There is a ton of data out there and plenty of people are testing, but nobody knows how it all fits together,” said Hahmann, who joined UMaine’s School of Computing and Information Science in 2013. “We are building connections among different pools of data.”

With a $1.5 million, three-year grant from the National Science Foundation, Hahmann is leading a team from UMaine and three other universities to develop the Safe Agricultural Products and Water Graph, or SAWGraph. It is being developed for use by the U.S. Environmental Protection Agency.

The tool will be based on a prototype that Hahmann and colleagues are now building for Maine showing soil and water wells contaminated by the state’s now-defunct wastewater sludge spreading program. The NSF grant will allow his team to refine and expand the prototype.

PFAS are a group of over 9,000 manmade chemicals used since the 1950s in industrial and household products like waterproof clothes, nonstick cookware and firefighting foam. Studies show that PFAS is linked to cancer, kidney malfunction, immune suppression and pre-eclampsia.


Their long-lasting carbon-fluoride bonds break down slowly, making them durable and highly resistant to heat, corrosion, water and stains. They build up over time, in the environment as well as in people. They can be found in rivers, eggs, deer, breastmilk, blood and even rain.

The national tracker will strive to connect testing data uploaded from state and federal records back to the likely source of contamination, note the potential impacts on food and water supplies, and map out how PFAS travels through the environment.

Once complete, SAWGraph will power an online map that will display contamination sites color-coded based on where the PFAS was found (soil, water, farm, food, domestic or wild animal), the source of the PFAS, and if the area was ever fertilized with wastewater sludge.

SAWGraph users can then break down the information based on the category of contamination and location, from the state to the municipal level, Hahmann said. New data from state and federal agencies will automatically be uploaded into the software as it becomes available.

“We’ve been talking with Maine and federal agencies to see what they would like to see,” he said. “We can create and present multiple sets of data at once, which can help with rather complex queries about things people really want to know, rather than just show rows and columns of numbers.”

Eventually, SAWGraph users should be able to look at data from all the wells located downstream from any water source polluted by PFAS, for example. They will be able to see what counties have undergone testing, and which have the highest and lowest levels of PFAS contamination.


The tool also could help users decide for themselves if nearby food or water supplies are possibly at risk, Hahmann said. It could help the public identify possible threats to their properties, and state and federal agencies determine where else testing might be needed.

Scientists could use it to identify what other data is needed to tackle the PFAS threat, Hahmann said.

“We’ve done some testing, but we only have so much capacity,” he said. “We can’t test everything.”

Maine is on the front lines of PFAS legislation. Last year, after a string of farms connected to the state’s decades-old sludge spreading program shut down because of PFAS contamination, Maine became the first state to ban sludge recycling and PFAS in nonessential products.

Maine is halfway through its review of 1,100 sites where sludge was used as farm fertilizer. It has found 49 farms with high PFAS levels. As of June, the results weren’t great. About 23% of the wells exceeded the state’s interim drinking water standard. The soil at 39 farms exceeded safe hay and silage levels.

Over half of the 5.2 million tons of sludge produced in the U.S. each year is applied to farming fields or forests, often for free or far below the price of chemical fertilizers. Before PFAS, it was seen as a win-win, saving farmers’ money and closing the waste recycling loop.

In 1997, at the height of Maine’s sludge spreading days, the state sent 48% of its 267,000 tons of sludge to farmers to be applied to the fields, turned 38% of it to compost, and buried the final 1% in a landfill, according to state Department of Environmental Protection records.

By 2021, the sludge numbers had flipped: Maine buried 82%, composted 11% and spread 6%.

In 2022, after a string of farm closures, Maine became the first state to ban all sludge recycling. Some states, like California, ban sludge landfilling and require it to be spread to reduce methane emissions.

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