CHEMICAL PROFILES|Why Is Safety Assessment Possible For More Chemicals in California?

California has a number of state laws on toxic chemicals that have no federal equivalent. These have stimulated California to make major contributions to the development of risk assessment values for toxic chemicals and to invest in extensive exposure monitoring. As a result, the state is in a significantly better position than U.S. EPA to assess the safety of toxic chemical releases reported to the Toxics Release Inventory.

Several California laws create unique incentives for the state to calculate risk assessment values and for industry to desire, rather than delay, their adoption. Under Proposition 65, businesses that expose individuals to chemicals that are know to the state to cause cancer or reproductive toxicity are required to provide warnings - unless they can demonstrate that exposures pose no significant risk of adverse health effects. By placing the burden of proving relative safety on toxic chemical users, Proposition 65 has created a demand in the business community for the state to adopt standards that define levels of chemical exposure that pose no significant risk. In California, it is not in the business community's interest to delay the adoption of health-based standards with interminable scientific debates. If the standards are not available to define legal exposures, companies can be subjected to law suits for failing to warn about toxic exposures. This is a stark contrast to the incentives that businesses confront under most national environmental statutes, where delaying U.S. EPA's ability to assess risks is often an effective strategy for delaying the adoption of regulatory controls.

Proposition 65 has stimulated an extensive effort by the California Environmental Protection Agency to calculate cancer potency values, and a modest effort to calculate no significant risk levels for reproductive and developmental toxicants. For example, the state has adopted potency values for over 400 carcinogens since 1986. In contrast, U.S. EPA has developed potency values for about 250 carcinogens, many of which remain unfinalized as industry continues to challenge their scientific validity.

California's Air Toxics "Hot Spots" Act has also provided a stimulus for the state to develop reference concentrations that can be used to assess the safety of hazardous air pollutants. This law requires certain high-emitting facilities to perform risk assessments on their air pollution and publicly disclose the results. The law covers almost 700 toxic chemicals, and CalEPA has devoted substantial resources to developing both acute and chronic risk assessment values to be used in these assessments. The state has adopted or proposed reference exposure levels for 255 toxic chemicals. In contrast, U.S. EPA has developed reference concentrations for only 87 chemicals.

Several other California laws have provided a stimulus for the state to conduct more local monitoring of exposure to toxic chemicals than U.S. EPA. The 1983 Toxic Air Contaminant Identification and Control Act created the country's most extensive program to control air toxics. As part of the contaminant identification process, the California Air Resources Board was charged assessing the potential for human exposure to air toxics. A statewide ambient air monitoring program was established which reports air toxics concentrations for more locations in California than are covered by EPA's entire Urban Air Toxics Monitoring Program. Extensive efforts have also been made to monitor exposures to indoor air pollutants.

Other statutes have mandated surveys of public drinking water systems for toxic contamination and established ongoing monitoring of toxic contaminants in California surface water and biota.

While these California programs cover about the same number of chemicals as national monitoring (approximately 100), they provide this information for many more geographic locations in the state, so some regional exposure monitoring data is available for most urban areas in California.