The Los Angeles County Department of Public Health has published findings on soil samples taken near two businesses identified as emitting high levels of hexavalent chromium in the City of Paramount: Anaplex and Aerocraft Heat Treating. The samples were taken in May 2017.
One soil sample indicated a detectable concentration of chromium 6 at 0.4 mg/kg, which exceeds the EPA’s Regional Screening Level of 0.3 mg/kg but is below the California Human Health Screening Level of 17.0 mg/kg for residential soil.
Quoting from the report:
The low detection of chromium 6 at the ten soil sampling locations suggest that the majority of air emissions of chromium 6 from Anaplex and Aerocraft have either not settled or not persisted on the surface soils of nearby residential areas. In addition, historical deposits of chromium 6 may have converted to chromium 3, the non-toxic form of chromium, by organic matter in the soil environment.4 At this time, direct contact with or accidental ingestion of these surface soils would not appear to represent an exposure pathway of public health concern for chromium 6. Inhaling chromium 6 poses the most significant threat to public health, and efforts to reduce health risks should continue to focus on reducing air emissions from facilities emitting chromium 6.
The complete report can be accessed on the LA County Public Health website located here. Tetra Tech’s summary of the results can also be viewed and downloaded here; this presentation will be further explained at the September 19th City Council meeting.
The City of Paramount partnered with the County to provide split sample testing of the results to help ensure validation on the findings.
In addition to measuring hexavalent chromium levels in the soil, the report also analyzed several other metals and made the following comments:
Four metals were detected at a concentration above state or federal health screening levels, namely, arsenic, cadmium, chromium 6 and lead. Arsenic, cadmium and lead were found to be within typical local background levels. A background reference value was not established for chromium 6, however, because it was not detected in any of the background samples. Since chromium 6 does not occur naturally in soils, any detectable level of chromium 6 would be in excess of background levels. Ten other metals (antimony, beryllium, cobalt, copper, manganese, molybdenum, nickel, titanium, vanadium and zinc) were detected at concentrations above local background levels, but below all available health screening levels.