Damian Applied Toxicology, LLC

 

USEPA Issues New Version of Regional Screening Levels (November 2014)


USEPA has released an updated version of the Regional Screening Levels (RSLs). The USEPA RSLs are the most widely used and cited health-risk based screening levels for chemicals in soil in the United States. They are also an important source of risk-based benchmarks for current or potential drinking water sources for which no drinking water standard (Maximum Contaminant Level or MCL) exists. To a lesser extent they are also sometimes used as a source of health-risk based chemical limits in ambient (outdoor) air and indoor air. It is important to always use the latest version of the RSLs when using the RSLs to perform a screening evaluation of health risks at contaminated sites. Note also that the California Department of Toxic Substances Control (DTSC) has recently adopted the RSLs as the preferred risk screening benchmark for soil instead of the California Human Health Screening Levels (CHHSLs), except in a few cases (e.g. lead). The new RSLs can be found at this link:

http://www.epa.gov/region9/superfund/prg/



Bisphenol A Recently Listed Under California's Proposition 65 (May 2015)


Bisphenol A (BPA) was officially listed under Proposition 65 as a reproductive toxicant effective May 11, 2015. BPA was listed on the basis of female reproductive toxicity. BPA is used to manufacture numerous plastics, coatings and resins often used in consumer products. Coatings containing BPA have been used to coat food and beverage cans and line water pipes. When a chemical is listed under Prop 65 the manufacturer or distributor has one year to show compliance with Prop 65. For a reproductive toxicant such as BPA, compliance with Prop 65 entails either posting a warning sign or demonstrating through an exposure assessment (typically conducted by a toxicologist) that use of the product by the typical consumer will not exceed a “safe daily exposure level” (Maximum Allowable Dose Level [MADL]) established by the California Office of Environmental Health Hazard Assessment (OEHHA). In the case of BPA, OEHHA has not yet formally published an MADL, although an MADL of 290 µg/day has been proposed. However, now that BPA has been officially listed it is likely that the proposed MADL will be formally adopted soon..

USEPA Issues Corrected Version of Regional Screening Levels (January 2015)


USEPA has released an updated version of the Regional Screening Levels (RSLs). The USEPA RSLs are the most widely used and cited health-risk based screening levels for chemicals in soil in the United States. They are also an important source of risk-based benchmarks for current or potential drinking water sources for which no drinking water standard (Maximum Contaminant Level or MCL) exists. To a lesser extent they are also sometimes used as a source of health-risk based chemical limits in ambient (outdoor) air and indoor air. Normally the RSLs are updated twice a year in May and November. However, in some instances USEPA will update the RSLs if important changes to the RSLs are required in the interim. This latest update was necessary because the soil ingestion pathway was omitted for 17 chemicals. It is important to always use the latest version of the RSLs when using the RSLs to perform a screening evaluation of health risks at contaminated sites. Note also that the California Department of Toxic Substances Control (DTSC) has recently adopted the RSLs as the preferred risk screening benchmark for soil instead of the California Human Health Screening Levels (CHHSLs), except in a few cases (e.g. lead). The corrected RSLs can be found at this link: http://www.epa.gov/region9/superfund/prg/





(530) 220-0454

California DTSC Issues Risk Guidance Note Regarding USEPA Vapor Intrusion Response Action Levels for Trichloroethylene (TCE) (August 2014)


The California DTSC recently released a short risk assessment guidance note describing its position regarding USEPA’s Response Action Levels for TCE. While generally concurring with the USEPA action levels, DTSC notes some differences in approach between DTSC and USEPA. Most importantly, DTSC agrees that indoor air concentrations of TCE greater than the USEPA Urgent Response Action Levels should lead to immediate mitigation measures within a few days. In addition, DTSC strongly advises consulting with the DTSC project toxicologist for site-specific recommendations when indoor air levels of TCE exceed 1 µg/m³  at residential sites, or 3 µg/m³ at commercial/industrial sites. DTSC also recommends that a second indoor air sample be collected immediately if the first sample indicates a TCE concentration at or above 2 µg/m³ at a residential site, or above 8 µg/m³  at a commercial/industrial site. Other recommendations in the DTSC guidance include: 1) address seasonal variability by conducting repeat rounds of indoor air sampling during late summer/early fall and late winter/early spring, 2) the use of passive samplers to supplement more typical TO-15 sampling devices (i.e. Summa canisters) should be determined on a site-specific basis, and 3) stand-alone air purifiers containing carbon filters provide an additional means for immediate mitigation of excessive TCE levels in indoor air. Below is a link to the new DTSC guidance document:

http://www.dtsc.ca.gov/AssessingRisk/upload/HHRA_Note5-pdf-pdf.pdf

(530) 220-0454

Key Federal Court Decision Regarding Expert Testimony and Contaminated Sites  


In a recent federal court case (Leese v. Lockheed Martin Corp) the court ruled that it is insufficient for a plaintiff to sustain a private cause of action (i.e. demand remediation, claim damages) based on the mere presence of a contaminant on a property, regardless of whether the contaminant in question is a carcinogen, designated a hazardous waste, or because of any other known intrinsic properties of the chemical.  The court ruled that under RCRA (Resource Conservation and Recovery Act) a plaintiff must show that the contamination actually poses an “imminent and substantial risk of harm to human health” at the levels found on the subject property. Furthermore, this opinion must be rendered by an appropriate expert, typically a toxicologist. This case highlights the importance of quantitative health risk assessment in demonstrating the presence or absence of chemical-related health risks. For more information about this case please visit the following link:

http://www.blankrome.com/index.cfm?contentID=37&itemID=3378

USEPA Issues Latest Version of Regional Screening Levels

(May 2014)


USEPA has just released an updated version of the Regional Screening Levels (RSLs) (dated May 2014). The USEPA RSLs are the most widely used and cited health-risk based screening levels for chemicals in soil in the United States. They are also an important source of risk-based benchmarks for current or potential drinking water sources for which no drinking water standard (Maximum Contaminant Level or MCL) exists. To a lesser extent they are also sometimes used as a source of health-risk based chemical limits in ambient (outdoor) air. It is important to always use the latest version of the RSLs when using the RSLs to perform a screening evaluation of health risks at contaminated sites. Note also that the California Department of Toxic Substances Control (DTSC) has recently adopted the RSLs as the preferred risk screening benchmark for soil instead of the California Human Health Screening Levels (CHHSLs), except in a few cases (e.g. lead). The new RSLs can be found at this link: www.epa.gov/region9/superfund/prg/


California DTSC Issues Important Updates to Vapor Intrusion Models


The California Department of Toxic Substances Control (DTSC) recently issued revised versions of their Johnson-Ettinger (JE) vapor intrusion models for soil gas and groundwater. These models are used throughout California to assess indoor air risks related to the intrusion of volatile chemicals into buildings. The changes to the models are the most significant since 2004. Some of the changes make the models more “user-friendly”. One such change is the addition of drop-down tabs that automatically select appropriate default exposure parameters for the desired receptor (exposed) population (e.g. residential or commercial). This drop-down tab also makes it easier to specify an alternate receptor population. Another such change is the addition of an input cell that makes it easier to allow a user-specified air exchange rate. One of the most important changes is the addition of an “exposure time” parameter. This parameter allows the user to adjust for daily exposures of less than 24 hours. Incorporation of the exposure time parameter also renders the DTSC JE models more consistent with current USEPA calculation methods for inhalation route health risks. Another important change is the use of a DTSC default attenuation factor of 0.05 that will apply automatically to subslab soil gas samples.


California DTSC Issues Risk Guidance Note Regarding USEPA Vapor Intrusion Response Action Levels for Trichloroethylene (TCE)


The California Department of Toxic Substances Control (DTSC) recently (Aug. 23, 2014) released a short risk assessment guidance note describing its position regarding USEPA’s Response Action Levels for TCE (see article below). While generally concurring with the USEPA action levels, DTSC notes some differences in approach between DTSC and USEPA. DTSC strongly advises consulting with the DTSC project toxicologist for site-specific recommendations when indoor air levels of TCE exceed 1 µg/m³ at residential sites, or 3 µg/m³ at commercial/industrial sites. DTSC also recommends that a second indoor air sample be collected immediately if the first sample indicates a TCE concentration at or above 2 µg/m³ at a residential site, or above 8 µg/m³ at a commercial/industrial site. Other recommendations in the DTSC guidance include: 1) address seasonal variability by conducting repeat rounds of indoor air sampling during late summer/early fall and late winter/early spring, 2) the use of passive samplers to supplement more typical TO-15 sampling devices (i.e. Summa canisters) should be determined on a site-specific basis, and 3) stand-alone air purifiers containing carbon filters provide an additional means for immediate mitigation of excessive TCE levels in indoor air. The DTSC risk assessment note can be accessed here: http://www.dtsc.ca.gov/AssessingRisk/upload/HHRA_Note5-pdf-pdf.pdf

USEPA Region 9 Issues Trichloroethylene (TCE) Vapor Intrusion Response Action Levels (July 2014)


On July 9, 2014 USEPA Region 9 issued interim Response Action Levels (RALs) for TCE in indoor air due to vapor intrusion. The purpose of the RALs is to protect pregnant women and women of child-bearing age generally from excessive TCE exposure, and provide benchmarks for when expedited mitigation of a TCE vapor intrusion situation is needed. Two tiers of RALs have been recommended: Accelerated RALs and Urgent RALs. The Accelerated RALs are 2, 8 and 7 µg/m³ corresponding to residential, commercial (8-hour workday), and commercial (10-hour workday) exposure scenarios, respectively. The Urgent RALs are 6, 24, and 21 µg/m³ for the residential, commercial (8-hour workday), and commercial (10-hour workday) exposure scenarios, respectively. For indoor air exposures to TCE equal to or less than an Accelerated RAL routine monitoring is recommended. For indoor air exposures to TCE greater than the Accelerated RALs but less than the Urgent RAL, Region 9 recommends “early mitigation measures be evaluated and implemented quickly, and their effectiveness …. confirmed promptly”. For indoor air exposures greater than the

Urgent RAL Region 9 recommends that "mitigation measures be initiated immediately and their effectiveness … confirmed before any additional exposure is allowed to occur”. Temporary relocation may be required under these circumstances. It is unclear at this time to what extent California and other states will incorporate these RAL recommendations in their vapor intrusion regulatory programs. For more information on the new RALs visit this link:

http://www.epa.gov/region9/superfund/prg/files/r9-tce-interim-action-levels-response-recs-memo-2014.pdf

 

Risk Assessment News and tips

 

California Proposes Nation's First Drinking Water Standard for Hexavalent Chromium


The California Department of Public Health (CDPH) has recently proposed a drinking water standard for hexavalent chromium of 10 ppb (10 µg/L). The impetus for developing a drinking water standard for hexavalent chromium is the relatively recent finding by the National Toxicology Program that hexavalent chromium is carcinogenic via the oral or ingestion route of exposure. For more information on the proposed standard visit this link: www.cdph.ca.gov/Pages/NR13-037.aspx