As Tucson-area officials struggle with chemical compounds known as PFAS turning up in drinking water, a scientific debate is building nationally over how much PFAS is too much.
But even as agencies come up with widely different standards on the issue, Tucson Water officials today say they believe the water they served to thousands of customers for an unknown period until late August was safe to drink.
That’s even though its PFAS levels in some areas of the city exceeded those that a federal agency recommends, that the state of Vermont requires and that at least two other states are considering.
The levels of PFAS (perfluoroalkyl compounds) in drinking water served to Tucson customers from a south-side treatment plant, of up to 30 parts per trillion, were first reported in the Star on Sept. 30.
The utility’s reasoning is that the only national standard existing today for the recommended maximum level — from the Environmental Protection Agency — is more than twice what Tucson Water was serving its customers.
“The water is safe for all uses including drinking,” Tucson Water said in a fact sheet last week. “It was also safe during the time period discussed in the Sept. 30, 2018 Arizona Daily Star article.”
Yet the EPA and another federal agency appear to be at odds over this very issue.
The EPA has since 2016 recommended no more than 70 parts per trillion of the two most common PFAS compounds for people who drink it over a lifetime.
Last June, a federal public health agency that’s part of the Centers for Disease Control, the Agency for Toxic Substances Disease Registry, released a previously suppressed draft report that in effect recommended no more than 18 parts per trillion for the same compounds.
Various states are all over the map on this question. Vermont allows 20 parts per trillion, less than one-third of what EPA recommends in drinking water. New Jersey and California are considering 27 parts per trillion.
Minnesota recommends 35 parts per trillion for one common PFAS compound and 27 for another. Michigan has a health advisory level of 70 parts per trillion for determining whether groundwater should be cleaned up. Its government has convened a scientific panel to consider if that should be lowered.
The EPA is also considering whether to impose formal drinking-water limits on the compounds and whether to classify PFAS as hazardous substances. That would increase the agency’s authority to clean them up in its Superfund toxic waste remediation program.
Generally, say researchers, standards for how much PFAS should be in water are growing tighter. The EPA lowered its PFAS health advisory from 600 to 70 parts per trillion only two years ago.
The vast majority of states for now are following the EPA’s recommendation of 70. Arizona legally has no choice but to do that. Our state law forbids officials from imposing environmental standards stricter than those of the feds.
Some researchers are calling for even lower levels, with a 5-year-old Harvard University study urging no more than 1 part per trillion PFAS. The advocacy-based Environmental Working Group says there is no safe PFAS level in drinking water, based in part on a German study.
Yet an Australian federal health agency concluded last summer after its review that there’s no evidence linking PFAS compounds to human health problems, although it added that such health impacts can’t be ruled out.
The U.S. EPA has concluded PFAS compounds are possibly carcinogenic to humans.
Wasn’t unsafe to drink, Tucson Water says
Tucson Water had told the Star in late September that it had shut down a south-side water pollution treatment plant from Aug. 23 to Sept. 17 after discovering it contained PFAS concentrations of up to 30 parts per trillion in its water.
The utility had not found the compounds in that water before because, it admitted last month, it was sampling for them from what turned out to be the wrong water main — a sampling point that had been put in place in 2000, long before current Tucson Water Director Tim Thomure took the job in 2016.
The highest levels were found in water served to customers at the southern end of where the city delivers water from what’s known as the Tucson Airport Remediation Project or TARP plant. Farther north, levels dropped to 1.9 parts per trillion.
The plant’s water goes to a large V-shaped area, population about 60,000, stretching north from East 29th Street through downtown to just north and west of the city limits, and flanking Interstate 10. The area spans as far west as the Tucson Mountains foothills and as far east as North Campbell Avenue and beyond.
In the past few months, since CDC’s toxic substances review agency report came out, Tucson Water has sought to keep its drinking water supplies to 18 parts per trillion of PFAS.
To meet that goal with the TARP water, it took a number of steps to reduce PFAS concentrations in it, by blending it with cleaner water from elsewhere and shutting off three south-side wells with higher PFAS concentrations that were being fed to the treatment plant.
The utility has taken a second round of samples and said preliminary results show the levels will be below 18, though it can’t confirm that until receiving all the data.
But the utility took those actions out of “an abundance of caution,” not because it believed the water was unsafe to drink, Tucson Water’s fact sheet said.
“We have set an operational target of 18 ppt to allow a wide margin of safety, and in consideration of changing scientific consensus about at what levels a future advisory or standard might be set,” the utility posted on Twitter last week.
“Would you give it
to your kids to drink?”
Figuring out if that water was safe is “quite overwhelming and confusing when so many different agencies have different values,” responded resident Cindy Dooling, who lives near El Camino del Cerro where the nearest PFAS sampling point came back at 8.6 parts per trillion in August.
Agreeing, Dunbar Spring resident Chris McCreedy asked how the utility can be so certain the water is safe when agencies are saying something different.
“Obviously if there is a difference, if there are reasons for the differences, I would want to know what the reasons are,” said McCreedy, a desert ecologist and researcher. “I don’t know who was right, what to believe.”
Dooling’s question for Tucson Water is, “Would you drink that water, and would you give it to your children to drink?”
She is a retired former acting vice chancellor for information technology at Pima Community College.
Today, she said, people are probably more skeptical than ever about what they’re told is safe, “especially from our government when they can’t agree for themselves on things and when they are lowering environmental standards so much,” said Dooling, referring to deregulatory efforts the Trump administration has made.
“It makes us very leery when they say ‘it’s not as bad as you think,’” she said. “How can we trust that?”
Friday, Tucson Water director Thomure replied that he drinks TARP water “every day at work,” since the utility’s office on West Alameda Street downtown along with City Hall “lie in the heart of the TARP delivery zone.”
Not only has he worked downtown most of his career in Tucson, his first house here, where he and his family lived three years, was located within the TARP delivery area, he said.
“Our kids were in grade school during those years, and they drank the water. Our beloved cat, Ricky, also drank the water, and lived to be 21 years old,” Thomure said.
Tucson Water said it relies on the EPA guidelines because the EPA is the regulatory agency that oversees the U.S. Safe Drinking Water Act and is the recognized authority for the water industry.
“The process and methods that US EPA uses to develop their water quality standards are robust, consistent, and well understood. Often, the first step before a regulatory standard is set by US EPA is for them to issue a health advisory. Health advisories are non-regulatory and provide conservative guidance to protect public health. Finally, they are based on peer-reviewed scientific data,” Tucson Water said in its fact sheet.
As for the Agency for Toxic Substances Disease Registry report, Tucson Water said it considered its recommendations to develop its PFAS target level of 18 parts per trillion.
But, “We do not conclude from that study that water containing PFC’s above 18 ppt is dangerous to public health,” the utility fact sheet said. PFC is another acronym for the class of chemical compounds. The utility said the report wasn’t intended to be used that way and to do so is a misuse of its conclusions.
A Harvard University professor who has extensively studied PFAS health effects says Tucsonans who drank water at 30 parts per trillion shouldn’t panic. But they should be concerned that such water may not be safe to drink, said professor Elsie Sunderland.
By contrast, in some places in the U.S., people have been getting water with tens of thousands of parts per trillion, said Sunderland. “If that was the case in Tucson, I’d say absolutely, ship in other water,” said Sunderland, an environmental chemistry professor. “In this case, I’d say it’s good to talk to people about reducing their overall exposures from PFAS in consumer products, and to water suppliers about reducing concentrations. If you’re concerned about it, by all means, get a water filter or switch to bottled water.
“If you told me your water was at 1,000 or 10,000, I’d say absolutely do not drink that water. If you drank water at this level, 30 to 70 for your entire life, I wouldn’t feel great about that,” Sunderland said. “It does say to me it’s something you should flag. You don’t want to ask these questions about your water. You want to know it’s safe.”
One key factor in determining if the water is safe is the population consuming it, how much water they drink and their overall health, she added.
“That’s especially with immune suppression,” Sunderland said. “If you have a healthy immune system, the likelihood of impact is low. If it’s compromised, the likelihood is much higher.”
PFAS is a widely used acronym for perfluoroalkyl compounds. They’re fluorine-based chemicals that were widely used in this country in a huge variety of applications but have gradually been phased out due to increasing concerns about health impacts. Today, the two most common ones, PFOA and PFOS, are no longer manufactured or sold in this country.
They’ve been used to protect paper and cardboard packaging products, carpets, leather products and textiles from stains, repelling water, grease and soil from the products, said CDC’s Agency for Toxic Substances Disease Registry’s June 2018 report. They’re best known for having been used as nonstick coatings on cookware, in food packaging and particularly in firefighting foam at airports and military bases, including Davis-Monthan Air Force Base in Tucson.
The compounds are considered stable in the environment, don’t break down easily in soil or water and tend to bioaccumulate in humans and animals. Some people call them “forever chemicals.” They’re mobile in soils and often leach into groundwater, the Agency for Toxic Substances Disease Registry (ATSDR) report said.
Measurable levels of the compounds have typically been found in the bloodstream of the general population but levels have generally dropped significantly since the late 1990s as their use declined, the report said.
The compounds have been known to increase peoples’ cholesterol levels, damage the liver, decrease how well people respond to vaccines, and increase thyroid disease risks, the report said. They can increase risks of asthma, decrease women’s fertility and increase pregnant women’s risk of high blood pressure and signs of damage to other organs, most often the liver and kidneys. They can also lower infant birth weights, although not necessarily low enough to damage their health.
As for cancer, the World Health Organization’s International Agency for Research on Cancer and the EPA have concluded that PFOA is possibly carcinogenic to humans. Increases in testicular and kidney cancer have been observed in highly exposed humans, the ATSDR report said.
The reasons for differing agency recommendations for PFAS in drinking water start with the sheer complexity of the issue, the enormous number of research papers written on it and the fact that scientists have only been seriously studying its impacts since the 1990s.
In general, researchers are finding impacts to people at lower levels as time passes, said Harvard’s Sunderland.
A growing number of studies are suggesting that the EPA’s 70 parts per trillion advisory level is not sufficient to protect human health, said Joseph Braun, a Brown University professor and epidemiologist.
But it’s also not clear what cut-off level will maximize benefits to human health, as a number of factors go into making such calculations, Braun said. They include which impacts you’re looking at and what groups or subgroups of people you’re studying, he said.
“We are still identifying new health effects associated with PFAS exposure,” Braun said.
In Colorado, the state uses the EPA’s health advisory for PFAS in drinking water because its state policy in setting health advisories “is to rely on federal risk assessment values if we can,” said Kristy Richardson, an environmental toxicologist with the Colorado Department of Public Health.
That’s because the feds usually go through a “very stringent peer review process” in deciding on advisories, both internally within their agencies and in seeking outside comment, she said, whereas some states don’t.
Another reason Colorado plans to rely on the EPA’s advisory is that officials find that the more different numbers are out there, the more confused the public gets, Richardson said.
“I think the ATSDR numbers are not the only numbers we are going to see. We know that EPA is working on other numbers. ... We are considering how we should approach all these chemicals. There’s a large family of (PFAS) chemicals and only a few have numbers for them. Only a few have toxicity information at all,” Richardson said.
But in Vermont, authorities picked a stricter standard than the EPA’s because it wanted to protect a different, sensitive population than the EPA standard is trying to protect, said Sarah Vose, Vermont’s state toxicologist. It considered the most sensitive population to be infants, from birth to age 1, whereas EPA considered impacts on lactating mothers, Vose said.
“Children with small bodies will eat more and drink more than adults. A higher ingestion rate will drive the health advisory lower,” Vose said.
Former EPA official Betsy Southerland said that agency decided to focus on lactating mothers because since companies have voluntarily stopped producing PFAS compounds, “we thought adult women would have higher concentrations of these chemicals in their blood than a newborn infant would. They have been exposed for years while these chemicals were still produced.” Southerland, as a top official in the EPA’s water office, oversaw the development of the EPA’s health advisory in 2016.
In New Jersey, the state’s Drinking Water Quality Institute also considered impacts of PFOS and PFOA to infants, said Keith Cooper, who chairs the group that advises the state Department of Environmental Protection on levels of chemicals to allow in drinking water.
The institute also gave more consideration than the EPA did to impacts of PFOA on women who may become pregnant and on their future children, and to the fact that some studies have shown current levels of PFOA in people’s blood already are causing impacts, said Cooper, a Rutgers University toxicology professor.
One problem with PFAS compounds is that they have a fairly extended half-life compared to many other substances, meaning that they remain active in a human body for years, Cooper said. Studies have found, for instance, that PFOA has a half-life in humans of 2.1 to 10.1 years and that PFOS has a half-life of 3.5 to 27 years, the ATSDR study shows. A half-life, more commonly used in describing radioactivity, is the amount of time that a substance takes to lose half its potency.
“With PFAS, you are chronically being exposed to these compounds,” Cooper said. “The half-life makes a huge difference.”
Said former EPA official Southerland: “It’s very important that this ATSDR study be thoroughly reviewed and that a decision be made if their recommendation is better than EPA’s recommendation. This is not a turf fight.
“This is an important public health issue that needs to be resolved by human toxicologists.”
“Would you drink that water, and would you
give it to your children to drink?” West-side resident Cindy Dooling, posing a question to Tucson Water
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