The Department of Toxic Substances Control [DTSC] is drafting regulations to add Chapter 51.3 to the California Code of Regulations, under Title 22, Division 4.5.
This rulemaking proposes to require that any human health risk screening or risk assessment shall use the most protective of the three federal and state accepted toxicity criteria sources for each cancer and non-cancer contaminant of concern for any site in California.
DTSC has determined that calculating screening levels and cleanup goals from a single source of toxicity criteria does not always provide the best protection to human health. DTSC proposes to require that any human health risk screening or human health risk assessment shall use the most protective of the following three toxicity criteria sources for each cancer and non-cancer contaminant of concern:
- Office of Environmental Health and Hazard Assessment Chemical Database, or its successor. As of November 12, 2015, the database is available online at http://oehha.ca.gov/tcdb/index.asp
- US EPA Integrated Risk Information System (IRIS) database. As of November 12, 2015, the database is available online at http://www2.epa.gov/iris
- Provisional Peer-Reviewed Toxicity Value (PPRTV). As of November 19, 2015, these values are available online at http://hhpprtv.ornl.gov/quickview/pprtv.php
As drafted, the regulations would provide that the point of departure for action level and screening level determinations, and remediation goals, based on human health risk is:
- An incremental excess lifetime cancer risk to an individual of 1 x 10-6, and
- A cumulative hazard index across all pathways and contaminants of concern (COCs) of 1.0.
These action levels, screening levels and remediation goals would be calculated using the toxicity criteria.
The initial reaction of many is that, on balance, the regulations could have the impact of lowering the levels for cleanup of contaminants, as well as increasing the potential liability and costs for site cleanups.
DTSC is hosting a public workshop on December 12 to discuss proposed regulations that would specify toxicity criteria for human health risk-based screening levels, action levels, and remediation goals. This workshop is the first step toward beginning the formal rulemaking process in 2017.
In addition to this workshop, DTSC is extending the opportunity for interested stakeholders and the public to ask questions or provide feedback on this proposed regulation during this informal review period. Comments will be accepted until January 16, 2017.