The study ​“is just show­ing us the tip of the ice­berg,” says author Philippe Grand­jean, Har­vard T.H. Chan adjunct pro­fes­sor of envi­ron­men­tal health and Uni­ver­si­ty of South­ern Den­mark pro­fes­sor of envi­ron­men­tal med­i­cine. What also remains large­ly undoc­u­ment­ed is the extent of expo­sure to work­ers on the front­line of this chem­i­cal use.

Drink­ing water sup­plies for at least six mil­lion Amer­i­cans con­tain tox­ic indus­tri­al chem­i­cals at lev­els that exceed the U.S. Envi­ron­men­tal Pro­tec­tion Agency’s (EPA) rec­om­mend­ed safe­ty lim­it. This num­ber is like­ly an under­es­ti­mate since the infor­ma­tion avail­able through the EPA does not include data for about one-third of Amer­i­cans — those 100 mil­lion or more peo­ple who rely on pri­vate wells or the vast major­i­ty of pub­lic water sys­tems that serve com­mu­ni­ties with pop­u­la­tions of 10,000 or less. These are the con­clu­sions of a new study whose authors include sci­en­tists at the Har­vard T.H. Chan School of Pub­lic Health, the Uni­ver­si­ty of Cal­i­for­nia at Berke­ley and the Cal­i­for­nia Depart­ment of Tox­ic Sub­stances Control.

While indus­tri­al sites were pre­vi­ous­ly rec­og­nized as sources of these high­ly flu­o­ri­nat­ed, tox­ic and envi­ron­men­tal­ly-per­sis­tent com­pounds, this is the first nation­wide study to doc­u­ment that waste­water treat­ment plants, along with mil­i­tary bases and air­ports where these chem­i­cals are used in fire-fight­ing foams, are also con­tribut­ing sig­nif­i­cant­ly to drink­ing water con­t­a­m­i­na­tion. The study reports ground­wa­ter and sur­face water near some of these bases and air­ports with con­cen­tra­tions of these chem­i­cals 1,000 to 10,000 times high­er than the EPA’s health advi­so­ry lev­el for drink­ing water.

While the EPA’s May 2016 fact sheet says, ​“Such con­t­a­m­i­na­tion is typ­i­cal­ly local­ized and asso­ci­at­ed with a spe­cif­ic facil­i­ty for exam­ple, an indus­tri­al facil­i­ty where these chem­i­cals were pro­duced or used to man­u­fac­ture oth­er prod­ucts or an air­field at which they were used for fire fight­ing,” the new study shows the con­t­a­m­i­na­tion is much more wide­spread. The study’s find­ings sug­gest that not only are far more peo­ple poten­tial­ly exposed through drink­ing water than pre­vi­ous­ly thought, but that the mil­i­tary bases and air­ports where these flu­o­ri­nat­ed foams are used may be hotspots of expo­sure. This means that in addi­tion to runoff from these sites, expo­sure to those work­ing with these foams may be a health con­cern, as sug­gest­ed by recent test­ing that showed fire­fight­ers to have ele­vat­ed blood lev­els of flu­o­ri­nat­ed com­pounds.

What are PFAS?

These syn­thet­ic chem­i­cals (they don’t occur nat­u­ral­ly) known as poly- and per­flu­o­roalkyl sub­stances, or PFAS, are used in water­proof­ing, stain and grease-resis­tant and non-stick coat­ings. They’re used in cloth­ing, fur­ni­ture, car­pets, paints and food pack­ag­ing, among oth­er prod­ucts. They are also used in plas­tics and com­put­er chip man­u­fac­tur­ing, and in the fire-fight­ing foams used in mil­i­tary train­ings and at air­ports. These com­pounds have been so wide­ly used over the past 60 years that the U.S. Cen­ters for Dis­ease Con­trol and Pre­ven­tion (CDC) has found these chem­i­cals in the blood of more than 97 per­cent of the Amer­i­cans test­ed. These chem­i­cals have also been found in new­borns’ umbil­i­cal cord blood, an indi­ca­tion of pre­na­tal exposure.

Giv­en the well-rec­og­nized poten­tial envi­ron­men­tal and health haz­ards of PFAS and wide­spread expo­sure, the EPA has recent­ly low­ered its drink­ing water health advi­so­ry lim­it for PFAS. But this is a guide­line, not an enforce­able stan­dard. The six PFAS com­pounds that the EPA is now mon­i­tor­ing in drink­ing water stan­dards are part of the agency’s Unreg­u­lat­ed Con­t­a­m­i­nat­ed Mon­i­tor­ing Rule pro­gram. This requires par­tic­i­pat­ing pub­lic water sys­tems to mon­i­tor for cer­tain con­t­a­m­i­nants and report on their pres­ence. But it doesn’t require pub­lic water sys­tems to ensure that the health advi­so­ry lev­els aren’t exceeded.

“Most waste­water treat­ment plants don’t remove these com­pounds,” explains study author Cindy Hu, doc­tor­al can­di­date in envi­ron­men­tal health at Har­vard T.H. Chan School of Pub­lic Health and Harvard’s John A. Paul­son School of Engi­neer­ing and Applied Sciences.

“We’re con­cerned about these chem­i­cals because they’ve been linked to a wide range of adverse health effects. And drink­ing water can be an impor­tant source of expo­sure,” says Hu.

Var­i­ous PFAS have been linked to cer­tain can­cers, ele­vat­ed cho­les­terol, immune sup­pres­sion, obe­si­ty, low birth weight, repro­duc­tive sys­tem prob­lems and hor­mone dis­rup­tion. Lev­els of PFAS found in the envi­ron­ment have also been linked to sup­pressed immune sys­tems in chil­dren.

“These com­pounds are incred­i­bly sta­ble, so they can leach into the ground­wa­ter over many years and they stay there,” says Grandjean.

“Their half life is on the order of sev­er­al years,” explained study co-author Lau­rel Schaider, research sci­en­tist at the Silent Spring Insti­tute. ​“If you stopped being exposed, it would take a cou­ple of years to reduce lev­els in your body by half,” said Schaider.

For this rea­son, says Grand­jean, ​“Even the small con­tri­bu­tions” – or expo­sures – ​“are what we wor­ry about.”

Even though the EPA recent­ly low­ered what it con­sid­ers a safe lim­it in drink­ing water, Grand­jean wor­ries that this lev­el is not suf­fi­cient­ly protective.

“Unfor­tu­nate­ly, I have to say, the EPA water lim­its are way, way too high,” he says. The con­cern is the large ​“num­ber of peo­ple that are exposed to lev­els that we can see are asso­ci­at­ed with adverse effects on the immune sys­tem and car­ry risks of mis­car­riage,” he explains. These are, he says, ​“lev­els that we’re not pro­tect­ing peo­ple against.”

Work­ers on the frontline

The fact that so peo­ple are like­ly exposed to PFAS through drink­ing water at lev­els of con­cern to sci­en­tists rais­es addi­tion­al con­cerns for peo­ple – like fire­fight­ers– reg­u­lar­ly exposed on the job.

Exist­ing stud­ies exam­in­ing fire­fight­ers for the pres­ence of per­flu­o­ri­nat­ed com­pounds in their blood have shown ele­vat­ed expo­sure after respond­ing to fires. A study of Cal­i­for­nia fire­fight­ers found such lev­els to be three times high­er than that of Amer­i­can men test­ed by the CDC. That these com­pounds per­sist in the body and can pro­duce adverse effects at low lev­els makes cumu­la­tive expo­sures a con­cern. For female fire­fight­ers there’s the addi­tion­al con­cern that these chem­i­cals can be passed on to a fetus or infant.

Accord­ing to the U.S. Bureau of Trans­porta­tion, there are about 19,299 air­ports in the Unit­ed States, a num­ber that includes both mil­i­tary and civil­ian air­ports. And accord­ing to the U.S. Bureau of Labor Sta­tis­tics, there are an esti­mat­ed 137,300 U.S. work­ers employed in air­craft main­te­nance. But, to date, beyond the stud­ies look­ing at blood con­cen­tra­tions of PFAS in fire­fight­ers, the lim­it­ed occu­pa­tion­al expo­sure stud­ies for PFAS have large­ly been of work­ers at plants that man­u­fac­ture these chem­i­cals. And most such stud­ies have been con­duct­ed or com­mis­sioned by com­pa­nies pro­duc­ing the chem­i­cals. Some of these stud­ies have linked expo­sure to high blood cho­les­terol. Oth­ers have found links between expo­sure and some increased risk of prostate can­cer. But over­all, the indus­try-com­mis­sioned stud­ies say there is not yet suf­fi­cient evi­dence to estab­lish a causal link between PFAS expo­sure and adverse human health effects.

Yet, says Schaider, the stud­ies that might begin to link PFAS expo­sure to spe­cif­ic health out­comes in fire fight­ers and oth­ers using these foams haven’t been done. Some are now just get­ting under­way, through the Inter­na­tion­al Asso­ci­a­tion of Fire Fight­ers, which is exam­in­ing impacts of these fire-fight­ing foams on women fire fight­ers. But she says, ​“Unfor­tu­nate­ly, I don’t think this has been addressed yet.”

And while there is ample doc­u­men­ta­tion of ​“high­ly pol­lut­ed water” at air­ports and mil­i­tary bases where PFAS are used, ​“epi­demi­o­log­i­cal data on the mil­i­tary is hard to come by,” says study author Arlene Blum, exec­u­tive direc­tor of the Green Sci­ence Pol­i­cy Institute.

The solu­tion? For one, says Blum, ​“The mil­i­tary needs to needs to inves­ti­gate alter­na­tive fire-fight­ing foams that don’t con­tain any high­ly flu­o­ri­nat­ed compounds.”

“My key mes­sage,” says Grand­jean, is that because these chem­i­cals ​“are so per­sis­tent and we are dis­cov­er­ing more and more effects at low­er dos­es, we need to vig­or­ous­ly reduce these expo­sures.” And, he says, for peo­ple ​“who’ve been exposed over a long time, expo­sures should get as close to zero as possible.”