Mark Ruffalo stars in a new movie about a real-life corporate lawyer who exposed a chemical companys poisoning of local water systems serving tens of thousands of West Virginians. Dark Waters, released widely on Friday, touches on a major water contamination concern emerging across the country.

The role complements Ruffalos real-life activism. Over the years hes traveled the country denouncing oil pipelines and hydraulic fracturing for natural gas. Last month, he testified in Congress on the need for regulation of polyfluoroalkyl substances known as PFAS, the toxic chemical the new film depicts.

But Water Defense, the nonprofit Ruffalo founded in 2010, has quietly folded without explanation. It may have had something to do with a fight Ruffalo picked in Flint, Michigan.

Scientists and local activists first exposed excessive amounts of lead in Flints water in 2015, forcing the government to admit the water was unsafe for drinking and take remedial action. But in 2016, Ruffalo warned that Flints water was also unsafe for bathing.

Using its own technology a device Ruffalo had touted in a statement as a new product that will empower citizens to take water quality testing into their own hands Water Defense took samples from several Flint bathrooms. The organization reported it found dangerous chemicals in the bathwater, suggesting that it could be causing rashes. Ruffalo said on CNN that nobody could guarantee the water was safe for bathing.

Scientists disputed the warning , saying Water Defense had used nonstandard testing methods and that regular testing actually found typical amounts of contaminants that are monitored by federal regulations. Two years later, Scott Smith, Water Defenses chief investigator and the inventor of the propriety testing method, recanted his claims. Water Defense itself did not recant, but quietly deleted the scary press releases from its website.

Ruffalo himself seemed to drop the issue. Water Defense director Ramsay Adams told HuffPost last week that the organization has been inactive since 2017. Its website went down last week after a HuffPost inquiry.

Ruffalo declined to comment for this story.

The dispute over the safety of washing with Flint water played out primarily between Ruffalo and Marc Edwards, a Virginia Tech civil engineering professor who helped expose the lead levels and legionella bacteria in Flints water in 2015. Ruffalo said nobody could trust the government or even Edwards, who had been one of the governments harshest critics. Edwards then countered Ruffalo and said his bathing comments may have contributed to an outbreak of bacterial infections because people were hesitant to wash themselves using tap water.

Ruffalo had not completely fabricated concerns about bathing in Flints water. His warnings echoed complaints from many Flint residents since 2014, when the city, under the control of the state government, switched its water source to the Flint River instead of purchasing it from Detroits water system. The corrosive river water leached lead from the citys aging pipes, exposing Flint children to higher levels of the harmful neurotoxin.

Though lead exposure and legionella were the most prominent impacts of the Flint water crisis, right from the start city residents complained that their water appeared dirty and caused rashes. Officialdom struggled to explain why.

There was stuff in the water besides lead, said Harold Harrington, a plumbers union official with the UA Local 370 in Flint. He said he helped install dozens of filters in the wake of the water crisis and saw firsthand that a lot of people suffered from rashes. He said the union donated $25,000 worth of shower filters.

I believe 100% that water wasnt safe to bathe in, Harrington said, adding that he was glad when Ruffalo visited Flint in March 2016.

In August 2016 the Centers for Diseases Control published the results of an extensive review of water in the homes of people who were suffering skin problems. The agency reported that while the chlorine and mineral content of Flints water could have caused rashes when the city was using river water, there was no scientifically known explanation for the skin problems after the city had switched back to Detroits water in October 2015. But the report noted that stress can make skin problems worse. Flint residents had plenty to be stressed about.

Sometime after the dispute with Edwards, Smith and Water Defense parted ways. Smith wrote a long post on Edwards blog explaining the mistakes he believed hed made. He called the dangerous chemicals press release a good example of what I would not do in the future.

Smith has since repurposed his proprietary foam, the technology Water Defense used in Flint. Now hes testing its effectiveness for fighting algae blooms and legionella bacteria . (He had originally pioneered the foam as a way of containing oil spills.) He stressed that hes trying to avoid making any claims about his work without vetting from third party experts.

Ruffalo has moved on to campaigning against PFAS, a substance that has been used in non-stick Teflon and other commercial products and can accumulate in the human body with dangerous health effects, including cancer. He and other clean water advocates want Congress to crack down on the companies that polluted the environment with PFAS, and also to require regulators to monitor PFAS levels in public drinking water systems.

Ruffalo and the company that produced Dark Waters have launched a Fight Forever Chemicals campaign with tips for reducing exposure. The government is just beginning to study the possible health implications of drinking water contaminated with PFAS.

Republicans mocked Ruffalo at the November hearing for testifying on water issues as a celebrity with no scientific expertise. Ruffalo defended himself by saying he would rather not spend his time in the water space, but he felt like he has to.

I have been gifted with this outsize media coverage, celebrity, Ruffalo said. I could do car commercials and make a lot more money. I could use that [celebrity] for any number of things to ingratiate and enrich myself. I feel like from this blessing that Ive been given that I want to give people the voice that dont have a voice.