Metals, not PCBs, make Smurfit groundwater a health risk
Laura Lundquist
(Missoula Current) The Environmental Protection Agency has already determined that contamination of the Smurfit Stone mill site makes the groundwater unhealthy for people to drink, but results from a recent round of sampling are needed to learn whether the cancer and non-cancer hazard risks are worse than originally thought.
On Thursday, EPA human health risk assessor Will Holland explained to the Frenchtown Smurfit Stone Citizen Advisory Group how additional samples gathered from the Smurfit Stone mill site over the past two years might be used to revise the human health risk assessment the EPA wrote in 2022.
“I’m really focusing on groundwater, because that’s in the 2023 groundwater data summary report,” Holland said. “The human health risk assessment already concluded that there are risks above a level of concern in groundwater throughout the site. These cancer risks are really driven by arsenic and chromium.”
The Citizens Advisory Group has long been concerned about other contaminants connected to the milling process. The Smurfit Stone pulp mill produced bleached pulp for 39 years, and the site contains more than a million tons of bleached-pulp waste, which is a source of dioxins and furans. Groundwater and soil samples taken at the site contain dioxins and furans.
Dioxins, furans and dioxin-like PCBs often occur together, the byproduct of pulp, paper or pesticide manufacturing, and can cause reproductive and developmental problems, damage the immune system and cancer in people, fish and wildlife. Another type of PCB’s at Smurfit Stone was used in the electrical transformers. Even though there are different kinds of PCBs, the EPA originally sampled only for overall PCB presence, so it was impossible to identify the sources of PCB.
In 2021, Jamie Holmes, consulting scientist and vice president of Abt Associates, said the primary PCB found in fish samples from the Clark Fork River was PCB 126, the most toxic of 209 PCB-based chemicals called congeners. That means it didn’t come from the electrical transformers on the Smurfit site, which used Aroclor, a different congener. The site has other sources of PCB, even though the U.S. banned all PCBs congeners in 1978 after their toxicity and environmental longevity were discovered.
In 2023, at the insistence of the Citizen Advisory Group and Missoula County, the EPA sampled wells on the mill site for contaminants that hadn’t been assessed before, including PCB congeners and hexavalent chromium, which is more toxic than other chromium variants. In addition, 12 of the PCB congeners behave like dioxins, which makes them also more toxic, so they are combined into PCB TEQ or toxic equivalence.
Holland said the 2023 groundwater data showed low levels of PCB congeners in every well, but none exceeded the EPA drinking water standard. However, three wells contained enough PBCs to exceed an EPA screening level, which requires the EPA to evaluate whether PCBs need to be added into the human health risk assessment.
PCB TEQ, the toxic equivalence, was also low in most wells, although five wells had higher concentrations.
“If we included total PCBs as a contaminant of potential concern, it wouldn’t have a huge effect on the cumulative risk assessment estimates. Arsenic and chromium are dominating this; dioxins and furans contribute also,” Holland said. “At most, based on the 2023 data, we’re seeing (PCBs) might increase the risk estimate about 0.3%.”
Elena Evans, Missoula City-County Environmental Health manager, said it was good to finally get a better handle on what was happening with PCBs on the mill site. After Montana Fish, Wildlife & Parks had to issue a nonconsumption order for trout in the Clark Fork River due to dioxins and dioxin-like PCBs, the citizens advisory group wanted more information.
“We didn’t have testing of PCBs onsite that were incorporated in the human health assessment. So what we’re excited about, that we just received, are the first 33 samples of PCBs onsite that go beyond Aroclors,” Evans said.
EPA Project Manager Allie Archer said more data would be coming, because EPA technicians recently completed two weeks of sampling, which started on Oct. 21. They sampled groundwater in 59 wells for metals, dioxins, furans and PCB congeners and they sampled surface water for sediment at 13 sites, 11 of which were adjacent to wells, so they could try to connect the two.
More data will be needed, because the EPA laboratory made mistakes when testing for dioxins, furans and hexavalent chromium in the 2023 samples.
When measuring dioxins and furans, the lab used a detection limit that was, on average, 7 times higher than it should have been, Holland said. So they may have failed to catch samples that had dioxins and furans that would otherwise have been flagged. For samples where nothing is detected, the EPA still assumes the dioxin/furan level is half of the detection limit, instead of just zero, so that makes the 2023 results appear to be greater than they could be.
With the hexavalent chromium, the EPA was using a method where the samples had to be processed within 24 hour of being collected, but it was often impossible to get the samples out of the field and into the lab in that amount of time. So most of the 2023 samples were rejected.
Holland said the two problems have been fixed, so data from the next samples would be preferable to use.
In the meantime, the EPA recently updated toxicity information for hexavalent chromium based upon recent research that shows hexavalent chromium is less potent for cancer effects and more potent for noncancer hazards. Cancer effects are the risk of a chemical causing cancer and the more chemical that’s present, the greater the risk of cancer. Noncancer hazards are the risk of any other disease and risk doesn’t exist until a chemical exceeds a threshold. For example, the human body needs manganese, but above a certain threshold, manganese becomes toxic.
More sampling will occur in 2025, although Archer said no plan has been developed yet. Once all the sampling is complete and the data is in, Holland and his colleagues will decide whether it’s necessary to update the human health risk assessment or whether they can document small changes in a memo.
“I’m sensitive to the time frame because this remedial investigation has been going on for a couple years. We want to move forward with the cleanup,” “It will take a couple months to update the risk assessment and then there’s a comment period. The responsible parties will have to wait on that to draft the remedial investigation. So it could potentially add a year to the process. If all we’re doing is adding a contaminant of potential concern, we have to weigh whether it’s worth waiting to do a full update to do that.”
Contact reporter Laura Lundquist at lundquist@missoulacurrent.com.