It’s been almost two years since the Frank R. Lautenberg Chemical Safety for the 21st Century Act was signed into law reforming the Toxic Substances Control Act (TSCA). EPA is working to implement the law’s new requirements, including the requirement to assess the safety of existing chemicals — a daunting task, given the tens of thousands of chemicals used in commerce. While the implementation process has been fraught with controversy, the hazard evaluations that have been ongoing for years under the Safer Choice program may have a role to play in identifying safer chemicals that may not need a comprehensive risk assessment.
The Need for Prioritization
The first step in assessing risks associated with existing chemicals is to determine which chemicals will be first to be assessed, so that EPA can focus its resources on assessing and mitigating the most significant risks. By December 22, 2019, EPA is required to designate at least 20 chemicals as high priority substances and another 20 as low priority substances. A high priority substance is defined as “a chemical substance that the Administrator concludes, without consideration of costs or other non-risk factors, may present an unreasonable risk of injury to health or the environment because of a potential hazard and a potential route of exposure under the conditions of use, including an unreasonable risk to potentially exposed subpopulations identified as relevant by the Administrator.” A low priority substance is one that the Administrator concludes, based on sufficient information, does not meet the criteria for a high priority substance. Those chemicals designated as high priority will be required to undergo additional risk evaluation, and if necessary, restrictions will be imposed to eliminate any unreasonable risk. Those designated as low priority will not need to undergo a risk evaluation. As risk assessments of the high priority substances are completed, additional high priority substances must be designated (so there will always be 20 risk assessments ongoing); however, there is no statutory requirement for designation of additional low priority substances.
The first 40 chemicals for prioritization must be selected by March 2019 in order to complete the prioritization process by December 2019. So, how will EPA choose which chemicals will undergo the prioritization process? EPA held a public meetingin December 2017 to discuss possible approaches to identify candidates for prioritization. For low priority substances, one possible approach discussed was to consider chemicals published on the Safer Chemical Ingredients List (SCIL) as candidates.
Existing Data and Data Needs
SCIL was originally developed to identify chemicals suitable for use in Safer Choice-certified products, not to support TSCA implementation. However, because SCIL-listed chemicals have been determined to be among the safest in their functional classes, many would potentially meet the criteria to be designated as low priority substances. In particular, chemicals designated on SCIL with a full green circle have robust data sets based on experimental or modeled data and have been determined to be low hazard, suggesting at first glance that they would be unlikely to “present an unreasonable risk of injury to health or the environment”.
To meet the statutory requirements under TSCA, a hazard evaluation demonstrating a low hazard is not enough to determine whether a chemical meets the low priority chemical criteria. Factors indicating the extent of likely exposure to the chemical, including storage near significant sources of drinking water, the conditions of use, consideration of potentially exposed susceptible subpopulations, and production volume must also be considered. So, even in cases where a chemical listed on SCIL has very robust hazard data demonstrating minimal hazard, additional information would need to be collected to support the prioritization process.
There is a certain risk associated with initiating the prioritization process for a chemical: there is no “off-ramp” (meaning the chemical cannot be taken out of the prioritization process without being designated as either low-priority or high-priority), and there is a statutory deadline to complete the process once it begins. If the available data does not support designation as a low priority substance, the chemical will be designated as a high priority substance and undergo a full risk assessment. It remains to be seen whether the market will place value on the certainty of having a low priority designation for a chemical, creating an incentive for manufacturers to work with EPA to have additional chemicals designated as low priority beyond the statutory requirements, despite the risk and the effort required to collect the necessary data. During the 2018 Safer Choice Partner and Stakeholder Summit held last month, EPA reassured industry stakeholders that there is support during the data gathering process prior to formally submitting a chemical as a candidate low priority substance in order to mitigate the risk of an unanticipated outcome. Collection of this data may be a task that third party toxicologists – including third party profilers currently performing reviews for Safer Choice certification and listing ingredients in SCIL and CleanGredients – are equipped to assist with.
It is possible that some SCIL chemicals may not be good candidates for low-priority substance designation, in part due to insufficient data. For example, some SCIL-listed chemicals do not have reported production volume. Some (designated with a yellow triangle) may have some hazard concerns, even if they are considered safer alternatives within their functional class, and others (designated with a half green circle) may have less robust toxicological data available. It would seem that the chemicals designated with a full green circle (indicating a more robust data set and low hazard profile) that have well-understood characteristics and production volumes would be the best candidates for low priority designation.
The “Conditions of Use” Controversy
The framework rules promulgated for prioritization and risk assessment of existing chemicals under the amended TSCA have been not without controversy. One concern expressed by NGOs has been that EPA is excessively narrowing the “conditions of use” considered during prioritization and risk assessment, to the point that risks associated with chemicals may be underestimated. EPA has interpretedthe statutory requirements to mean that all conditions of use must be considered during the prioritization process; however, not every activity involving a chemical would necessarily be considered a condition of use. Specific activities considered as conditions of use would be identified and presented for public comment early in the prioritization process for each chemical undergoing prioritization. The conditions of use considered during the prioritization process may potentially be different from those considered during the risk evaluation process – e.g., the risk evaluation process may exclude certain conditions of use that are deemed to be low risk.
Even though all conditions of use must be considered during the prioritization process, framework rules promulgated by EPA last year determined that some circumstances in which a person might be exposed to a chemical would NOT be considered conditions of use. These circumstances include:
- Intentional misuse, such as inhalant abuse;
- Legacy uses with no ongoing manufacturing, processing, or distribution and associated disposal (e.g., disposal of materials in legacy use), such as use of asbestos insulation in older buildings and disposal of these materials when removed from a building; and
- Legacy disposal – i.e., exposure to chemicals disposed of in the past, such as through contaminated groundwater.
The decisions not to include these situations as conditions of use and to potentially limit which conditions of use are included in risk assessments have been controversial, in large part because risk is determined in part by total exposure to a chemical, including exposure via legacy uses and disposal. Therefore, failure to consider legacy uses may result in an underestimation of the overall potential risk associated with a chemical, both during the prioritization process and during the risk assessment phase.
Low Hazard = Low Risk
Controversy aside, the risk associated with a chemical substance is based on multiple factors, including the inherent hazard of that substance, as well as the dose-response relationship and the degree of exposure to the substance. Regardless of whether exposure is underestimated, a low-hazard chemical will be associated with low risk. Even in the context of political questions about which potential exposures are taken into account, the low hazard chemicals listed on SCIL seem to be a good starting point for identifying low priority chemicals, which are unlikely to present an unreasonable risk to either human health or the environment. While unknowns remain about stakeholder support for low priority designations beyond statutory requirements, and additional data will need to be collected to ensure that low priority prospects from SCIL do in fact meet the criteria for designation as low priority substances, there seems to be general support among Safer Choice stakeholders for the concept of using SCIL as a pre-screening tool to identify good low priority chemical candidates.
