Welcome to our website! Damian Applied Toxicology, LLC (DAT) is a scientific consulting firm that specializes in the application of advanced toxicology and chemical risk assessment methods to evaluate chemical exposures occurring in the environment (e.g. Brownfield and hazardous waste sites), food, consumer products (e.g. dietary supplements, drugs, cosmetics, pesticides), and the workplace (e.g. workers' compensation cases).

DAT uses state-of-the-science methods to independently and quantitatively evaluate potential health risks posed by chemicals to humans, wildlife and domestic animals. Typical clients of DAT include attorneys, mining firms, real estate developers, consumer product manufacturers, and environmental consulting firms seeking specialized expertise in the area of health or ecological risk assessment. These risk assessments can then be used by business decision-makers and regulatory agencies to determine appropriate mitigative measures if necessary to ensure adequate protection of public health and the environment. 

Paul Damian PhD, MPH, DABT, ERT is the Founder and Principal of DAT. He is a Board Certified Toxicologist (Diplomate of the American Board of Toxicology [DABT]) and European Registered Toxicologist (ERT). Dr. Damian has over 30 years of experience evaluating chemical
risks to humans and the environment in a wide variety of chemical
exposure circumstances and in numerous states across the country.

The main general service areas provided by DAT are shown below. Additional details are provided on our Services page. 

  • Contaminated site human health and ecological risk


  • Vapor Intrusion and indoor air health risk assessments

  • California Proposition 65 compliance evaluations for

           consumer products

  • Food, cosmetic, and nutritional supplement safety
    including Generally Recognized as Safe (GRAS) expert panel participation 

  • Adverse effects of chemicals, drugs and dietary supplements

  • Drug-induced liver toxicity cases

  • Drug impurity risk assessment

  • Computational and predictive toxicology for novel chemicals and drugs using QSAR and read-across methods

  • Expert witness/litigation support

California DTSC Issues New Health Risk Assessment Guidance Regarding Arsenic Bioavailability Adjustment  (September 2016) 

The California Department of Toxic Substances Control (DTSC) recently released (August 22) guidance for taking into account the ingestion bioavailability of arsenic in human health risk assessments at contaminated sites. A chemical that is highly bioavailable via the ingestion route of exposure is well-absorbed into the body. Chemicals with low bioavailability are poorly absorbed. Previously, DTSC had normally required the assumption of 100% (maximum) bioavailability for arsenic in site health risk assessments. This assumption may result in an overestimate of arsenic health risks at sites where the geochemical form of arsenic on the site actually has a lower bioavailability. For example, arsenic at mine sites in particular often has a bioavailability significantly less than 100%. The guidance specifies an in vitro bioavailability test method, called the California Arsenic Bioaccessibility or CAB method. The CAB method can be applied to site soil samples and the results converted to the corresponding in vivo bioavailability using a linear regression developed by DTSC and its research partners. The resulting in vivo bioavailability value can then be used to adjust the arsenic health risk calculations for the site. DTSC notes that this bioavailability adjustment is most likely to make a significant difference in the risk estimates at sites where arsenic concentrations are less than 500 mg/kg.  Also note that high levels of arsenic at a site that are due to historical pesticide application, rather than mining activities, are less likely to benefit from this adjustment. A copy of the guidance is available at this link: https://www.dtsc.ca.gov/AssessingRisk/upload/HHRA-Note-6-CAB-Method-082216.pdf

USEPA Finalizes Vapor Intrusion Risk Assessment Guidance (June 2015)

USEPA recently released the long-awaited final version of its vapor intrusion risk assessment and mitigation guidance. Vapor intrusion is the intrusion of volatile chemicals into an overlying building from contaminated soil, soil gas and/or groundwater. Two separate guidance documents were released on June 11 to address chlorinated volatile organic compounds (VOCs) generally, and petroleum-related compounds (e.g. benzene, toluene, etc.).  While emphasizing the importance of using multiple lines of evidence to assess vapor intrusion risks, the guidance documents rely extensively on the use of non-site-specific (generic), and conservative vapor intrusion screening levels (VISLs) calculated using a Vapor Intrusion Screening Level Calculator. The guidance barely mentions the Johnson-Ettinger vapor intrusion model, a powerful chemical transport model endorsed by USEPA for almost 20 years and widely used in many states (especially California) to develop site-specific estimates of vapor intrusion health risks.  The guidance recommends the use of models primarily for assessing risks to future development, rather than existing buildings.  The guidance places new emphasis on: 1) the need to use special risk assessment techniques to address carcinogenic chemicals that are considered to act via a mutagenic mode of action, and 2) addressing short-term or acute indoor air exposures caused by vapor intrusion. However, the guidance offers few details as to the methods that should be used to evaluate acute exposures. The guidance also clarifies that occupational exposure levels (e.g. PELs or TLVs) are not to be used for evaluating vapor intrusion health risks. At this point many states have already developed their own vapor intrusion risk assessment guidance so it will be interesting to see to what extent states adopt the new guidance. The two new guidance documents may be downloaded at the following link: http://www.epa.gov/oswer/vaporintrusion/guidance.html#PVIGuideFinal.

USEPA Issues Update of Human Health Ambient Water Quality Criteria for Surface Waters (September 2015)

USEPA has recently (June 2015) released an updated version of the human health ambient water quality criteria for surface waters. Required under Section 304(a) of the Clean Water Act, the criteria are typically applied to untreated, natural (ambient) surface waters such as lakes, rivers and streams. Ambient water quality criteria have been developed for both the protection of aquatic life and to protect human health based on potential drinking water and/or fish consumption. Although the criteria are USEPA recommendations, and do not constitute enforceable standards as issued, they may be adopted by the states as enforceable surface water quality standards. Unlike drinking water standards (Maximum Contaminant Levels) the ambient water quality criteria are developed without taking into consideration economic or technical feasibility issues. Updated human health criteria have been issued for 94 chemicals. Some important chemicals, including arsenic and hexavalent chromium, were not updated due to outstanding technical issues. The updated human health criteria reflect updated exposure parameters (e.g. drinking water consumption rate, fish consumption rate), updated toxicity criteria (i.e. the underlying toxicity data), and changes in USEPA risk assessment policy. Complete information regarding the updated criteria can be found at the following USEPA website:


The Importance of Reporting Limits at Brownfield Sites (May 2016)

It is especially important to carefully consider your analytical method reporting limits when investigating or remediating a Brownfield site (i.e., a contaminated site scheduled for redevelopment). Here’s why: Suppose your client (a developer) initially says they want to redevelop a contaminated site for commercial use (e.g. office buildings, a manufacturing facility or an industrial warehouse). Risk-based cleanup levels for commercial use are always higher (less stringent) than for residential use. You proceed with the investigation, selecting an analytical method that appropriately provides reporting limits just under the higher commercial use-based cleanup levels. However, after you collect and analyze your samples the developer changes their mind and now wants to develop the site for residential use. Unfortunately, the analytical method that previously provided reporting limits low enough to show compliance with the commercial use-based cleanup levels is not sensitive enough (reporting limits are not low enough) to show compliance with the lower residential-based cleanup levels. This means that even if a target analyte for the site shows as non-detect using the higher commercial use reporting limits it cannot be shown that it is safe for residential use and new samples will have to be collected and reanalyzed using a method that is more sensitive. Bottomline: if there is any possibility that the site in question may be redeveloped for residential use make sure your analytical method will provide reporting limits below residential use-cleanup levels. As an example, for volatile organic compounds (VOCs) in soil vapor, the standard EPA method 8260B may not be sensitive enough for some target analytes, and 8260B using Selected Ion Monitoring (SIM) mode for target analytes, or method TO-15 must be used instead.


Risk Assessment News and Tips

Please see our News page for additional risk assessment developments and tips.

(530) 220-0454

 Advanced Assessment of Chemical Risks to Health and the Environment


Damian Applied Toxicology, LLC