WILMINGTON — The chemical GenX is at the center of the Cape Fear region’s recent fears about the safety of drinking water. But according to a recent health assessment by state and federal agencies, the focus on tap water may obscure a larger problem.
GenX, manufactured by former DuPont subsidiary The Chemours Company, was a little known industrial chemical until early June. That’s when perfluoro-2-propoxypropanoic acid (PFPrOPrA), marketed by Chemours as GenX, became the target of intense scrutiny.
Little was known about the chemical: it had replaced the carcinogen C8 used by DuPont; it was being dumped into the Cape Fear River; and the Cape Fear Public Utility Authority – and other municipal utilities – were unable to filter it out.
Over the following weeks, debates over “who knew what and when” raged; at the same time there were few answers about the danger of Genx to humans.
Last Friday, the North Carolina Department of Health and Human Services released an update on the situation. It was a mixed bag. On the one hand, early results from testing in the Cape Fear and surrounding water sources showed lowered rates of GenX. On the other hand, the DHHS drastically reduced the “health goal” – the minimum amount in the water – to avoid health issues.
The level considered safe by the state was lowered from 71,000 parts per trillion to 140 part per trillion. According to the EPA, parts per trillion (also referred to as nanograms per liter) is about one gallon in 1.5 million Olympic swimming pools.
In other words, the amount of GenX in the water had decreased, but officials now consider it about 500 times more dangerous than they initially did.
How the new ‘health goal’ assessment was developed
There were several reasons for the increased concern over GenX, including a “different set of animal studies” that lowered the safe “health goal” level by a factor of 10. The state also reasoned that, since animal studies were short term, and GenX has been in the Cape Fear for decades, there was an “added uncertainty factor.” This also contributed to a lower heath goal level.
A final reason concerned the way in which people come in contact with GenX. It appears to significantly broaden the scope of concern over GenX.
Friday’s report reads:
“While the preliminary assessment assumed that drinking water was the only source of exposure, the updated value includes an assumption that only 20 (percent) of a person’s GenX comes from drinking water.”
This means that the vast majority – 80 percent – of the GenX exposure for those in the Cape Fear area might not be from drinking water. While this doesn’t render moot debates over bottled water and reverse osmosis, it certainly could re-position questions about drinking water in a much broader field of concern.
So, if not from drinking water, where are people being exposed to GenX?
Kelly Haight, spokeswoman for the DHHS, said, “there is potential for GenX to be found in other sources, such as air, soil and food, and we are accounting for that possibility.”
According to Haight, there are no current plans to “quantify these other source contributors.”
How did the DHHS arrive at the 20 percent number?
According to Haight, the “EPA’s practice is to use this (20 percent) default factor as a generic assumption when information is lacking about other sources of exposure in the environment, as is currently the case with GenX. NC DHHS’s use of the 20 percent factor was included based on additional review and consultation with EPA.”
Floors and ceilings
The 20 percent number is an EPA default assumption, but it is not the only one. According to the EPA’s website, there are several ways the agency estimates what they call the “relative source contribution” of exposure to a certain chemical.
That includes a “ceiling,” a high estimation, when the EPA is reasonably sure exposure is from drinking water.
while the DHHS was clear that EPA standards were instrumental in its revised health assessment, the EPA itself did not respond to questions about other potential exposure risks for GenX.
“For drinking water contributions between eighty and one hundred percent, EPA uses an eighty percent ‘ceiling’ (i.e., maximum drinking water contribution). The ‘ceiling?’ accounts for the possibility of unusual exposures (e.g., individuals exposed to higher than currently indicated levels of a contaminant in food) or for changes in the distribution of a contaminant in the environment,” the agency’s website states.
On the other hand, when the agency is reasonably sure drinking water is not the main culprit, it uses a “twenty percent ‘floor.’”
According to the EPA site, “(f)or drinking water contributions less than twenty percent, EPA uses a twenty percent ‘floor’ (i.e., minimum drinking water contribution). The ‘floor’ represents a level below which additional incremental protection is negligible. It also indicates that control of other more contaminated media (e.g., air) will have greater reduction in daily exposure.”
The EPA’s choice of the floor, rather than the ceiling, indicates the agency believes a considerable amount of GenX is coming from somewhere else. However, while the DHHS was clear that EPA standards were instrumental in its revised health assessment, the EPA itself did not respond to questions about other potential exposure risks for GenX.
Unfortunately, without further testing – for air, soil and food – it remain unclear how people are being exposed to GenX.
It also remains unclear what prolonged exposure means. According to a response to New Hanover County from the DHHS, “There are no studies in humans and limited animal studies on cancers related to GenX. One animal study reported increased rates of specific cancers including pancreatic, liver, and testicular cancer. Whether or not animal effects will be the same in humans is not known.”
Based on its own correspondence the EPA, the state DHHS notes “there is not enough information at this time to identify a specific level of GenX that might be
associated with an increased risk for cancer.”
Overall cancer rates in this region, according to the state, are no higher or lower than other regions of North Carolina.
Send comments and tips to Benjamin Schachtman at ben@localvoicemedia.com, @pcdben on Twitter, and (910) 538-2001.
