North Carolina: EQ not responsible for Apex contamination

Environmental testing has turned up widespread chemical contamination in Apex, N.C., but state officials say the pollution is not related to last month's fire at a hazardous materials handling facility in the Wake County town 15 miles southwest of Raleigh.

The pollution found is just the ubiquitous toxic residue of our times, they say.

"What we were looking for was any indication that homes or businesses might have been contaminated with heavy metals or other chemicals from the fire that could present a health risk to Apex citizens," says Robin Smith, assistant secretary for the environment at the N.C. Department of Environment and Natural Resources, in a Nov. 17 press release. "We didn't find that. We found the kind of thing you would find at low levels in any urban area."

But at the same time, DENR acknowledges that at least some of the contamination found in soil collected from neighborhoods around the plant appears to have possibly originated at the EQ facility. In addition, some of the pollution -- including toxic metals and solvents that EQ stored on-site -- were detected at levels that exceed health-based guidelines, thus posing a long-term risk to human well-being.

According to a report DENR released last week, tests conducted on 37 soil samples collected by its Division of Waste Management after the Oct. 5 blaze turned up toxic metals, solvents and benzene compounds at levels exceeding at least one of three regulatory limits set to protect human health: North Carolina's Soil Screening Level (SSL), EPA Region 9 Preliminary Remediation Goal (PRG) for Residential Soil, and EPA Region 4 PRG for Residential Soil. This is how the report describes those limits:

North Carolina Soil Screening Levels are calculated to be protective of groundwater. They reflect the levels for each chemical at which the chemical would have the potential to migrate through the soil and contaminate groundwater. The Soil Screening Levels are calculated by multiplying the North Carolina groundwater standards by soil fate and transport factors. EPA Region 9 Residential Soil Preliminary Remediation Goals (PRGs) are levels in soil protective of human health based on typical homeowner exposure to soil. They are calculated for a residential exposure of 350 days/year for 30 years. The EPA Region 4 PRG for arsenic is based on a noncancer endpoint and is protective of childhood exposure scenarios.

The tests found a dozen chemicals exceeding at least one of these limits. Among them were the toxic metals arsenic, cadmium, chromium, manganese, mercury and silver, along with tetrachloroethylene, a dry-cleaning solvent. In an inventory released after the fire, the facility reported having all of those chemicals onsite, except for manganese. However, EQ's permit did include a manganese-containing pesticide, bis(dimethylcarbamodithioato-S,S')-manganese.

The soil tests also turned up elevated levels of bromodichloromethane, a substance used mostly in labs and chemical manufacturing, as well as the following polycyclic aromatic hydrocarbons (PAHs), which have been linked to cancer in humans: benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthacene, and dibenzo[a,h]anthracenindeno(1,2,3,c,d)pyrene.

Every soil sample taken contained arsenic, with three of them containing the toxic metal at levels elevated beyond the regulatory guidelines considered. However, the study noted other potential arsenic sources on those properties, including treated wood decking and an automobile repair shop. (DWM's report does not explain why it took samples from spots with other obvious sources of contamination.) Noting that the overall distribution of arsenic "does not suggest dispersal from a point source centered on the EQ facility," DENR suggests that the widespread low-level contamination may be related to arsenic-based pesticides used in the area's once-booming tobacco farming industry.

Mercury was also found in 36 of the 37 samples. All of the samples exceeded North Carolina's SSL, though they were still within what the EPA considers the "naturally occurring" range. The tests also found several mercury "hotspots" exceeding the guidelines. However, one of those hotspots was near an auto maintenance and storage business, and the report notes that mercury is present in many car components including switches, anti-lock breaking systems and high-intensity headlamps.

State regulators conclude that the metal, tetrachloroethylene and bromodichloromethane pollution did not originate from EQ due to the distribution pattern, which does not appear to be centered on the facility. They also say that the source of the PAHs is "inconclusive" even though the compounds' distribution does suggest they may have come from EQ:

The samples demonstrating regulatory exceedances in soils are located in a general downwind direction from the EQ facility. However, there are other potential sources (i.e. automotive repair, landscape activities) for PAHs at each of the sampling sites. Additional sampling may be warranted to clarify the distribution and potential source(s) of these compounds.

Last week DENR also released the results of wipe tests, which collected residues from the exterior and interior of buildings in the vicinity of the EQ facility and tested them for contaminants.

The exterior wipe tests found a number of metals in the 72 samples collected, but none at concentrations exceeding health-based screening levels. The largest percentage was for one sample of lead, which was 53 percent of the screening level. Cyanides were not detected in any of the exterior wipe samples. One PAH was detected in each of eight wipe samples, but at very low concentrations.

DENR also collected wipe samples inside buildings from various horizontal surfaces, excluding floors. The interior wipe tests turned up one older home with elevated lead levels, but the agency concludes that it's likely due to lead-based paint. State health and town officials are doing a follow-up investigation of that home to confirm the source of the lead, according to the report.

The agency's off-site testing did not include dioxins, which are a contaminant of concern whenever there is a fire at a facility that -- like EQ did -- stores chlorinated compounds. However, an Oct. 30 DENR situation report did note that testing for dioxins was being done on the ash and other materials on-site, though results from those tests have not yet been released.