Chemicals found in more than 150million Americans' tap water raises cancer risk 33%
Americans exposed to 'forever chemicals' in tap water have up to a 33 percent higher risk of developing cancer, a new study warns.
In the most comprehensive study of its kind, researchers from the Keck School of Medicine of the University of Southern California looked at the link between polyfluoroalkyl substances (PFAS) - found in about 45 percent of drinking water supplies across the US - and the incidence of digestive, endocrine, respiratory, and mouth and throat cancers.
Past research has linked the chemicals, which accumulate in the body over time and are slow to break down, to a range of health problems, including kidney, breast and testicular cancers.
To paint a more comprehensive picture of PFAS and cancer risk, researchers looked at large population-level datasets to identify patterns of exposure and illness.
They found between 2016 and 2021, counties across the US with drinking water contaminated with PFAS had higher incidence of certain types of cancer.
Based on the latest data available from the Environmental Protection Agency (EPA), the researchers estimate PFAS contamination of drinking water contributes to 6,864 cancer cases per year.
That's only around 0.4 percent of all cancers, but researchers say it is still concerning as these numbers can accumulate year after year with mounting financial costs along the way.
The Environmental Working Group, an activist organization centered on environmental pollutants, mapped out the communities and military sites confirmed to have PFAS contamination
Last year, the EPA set the maximum contaminant levels for PFAS at 4.0 parts per trillion.
Counties where drinking water surpassed this level - such as Nassau, Suffolk, and Rockland in New York and Los Angeles, Orange, and Riverside counties in California - had a higher incidence of digestive, endocrine, respiratory, and mouth and throat cancers.
Increases in incidence rates ranged from slightly elevated, at two percent, to 'substantially elevated' at 33 percent.
Researchers found the increased incidence of mouth and throat cancers were linked to perfluorobutanesulfonic acid, or PFBS, which is a type of PFAS.
Males in counties with contaminated drinking water had a higher incidence of leukemia, as well as cancers of the urinary system, brain and soft tissues, compared to males living in areas with uncontaminated water.
Meanwhile, females had a higher incidence of cancers of the thyroid, mouth, throat, and soft tissues.
The exact numbers of cases were not detailed in the study.
PFAS are microscopic substances that take thousands of years to break down in the environment and human body, earning them the name 'forever chemicals.'
Their main purpose is to repel water and oil, which is what makes non-stick cookware easier to clean and why certain jackets and tents can withstand rain.
The chemicals can seep into the water supply from washing dishes and can enter food if packaging is made to be grease-resistant or if the non-stick coating on pots and pans begins to deteriorate.
PFAS are also common in pesticides used to feed crops, which produces chemical-rich runoff that can enter the drinking water supply. There is no level of safe exposure to the chemicals.
If a water provider knows there are forever chemicals in their system, they can treat it to limit the chemicals that end up in your tap.
An illustration of the distribution of PFAS in drinking water and annual average cancer incidence between 2016 and 2021
At home or from private wells, there are filters you can purchase to rid your water of these chemicals - but experts recommend only buying those that are independently certified to filter PFAS.
Consumer Reports recommends looking for filters with stamps from the National Sanitation Foundation, Water Quality Association or International Association of Plumbing & Mechanical Officials.
These range from $45 to as much as $1,200 - depending on whether you're looking for a counter top, under sink, faucet or pitcher filter.
In the recent study, the researchers obtained cancer incidence data from the US National Cancer Institute's (NCI) Surveillance, Epidemiology, and End Results (SEER) program.
The geographic coverage of the SEER database, which includes 22 cancer registries, is approximately half of the US population.
The geographic area coverage included Connecticut, Hawaii, Iowa, New Mexico, Seattle, Utah, Atlanta, Alaska Natives, Georgia, California, Kentucky, Louisiana, New Jersey, Idaho, New York, and Texas.
Meanwhile, the researchers used two different sets of PFAS data and looked to see if there was a correlation between chemicals in drinking water and cancer rates.
Some of the geographical hotspots where crossovers occurred included Chicago, New York, Georgia, Texas and California.
In addition to providing a roadmap for researchers, the findings underscore the importance of regulating PFAS.
Public water systems have five years to implement solutions to reduce PFAS in their water.
From 2029, the EPA will police levels of six types of PFAS in drinking water - PFOS, PFOA, PFNA, PFHxS, PFHpA, and PFBS - and systems with unacceptable levels, will be required to notify the public.
These were the same PFAS the researchers at the Keck School of Medicine covered during their analysis.
Dr Shiwen Li, the study's lead author, says the results show that the proposed changes may not go far enough and stricter limits may ultimately be needed to protect public health.
Commenting on the findings, he added: 'When people hear that PFAS is associated with cancer, it's hard to know how it's relevant.
'These findings allow us to draw an initial conclusion about the link between certain rare cancers and PFAS.'
