The TSCA New Chemicals Program – A Closer LookBy Jeffrey Hafer and Kelly Mayo, Senior Regulatory Scientists at knoell USA - 11th November 2019
Since the Lautenberg Chemical Safety Act was enacted in 2016 outcomes of Premanufacture Notice risk assessments for new chemicals have changed dramatically. Jeffrey Hafer and Kelly Mayo, Senior Regulatory Scientists at knoell USA, provide suggestions on how to maximize the chance of a successful outcome.
The initial driver for amending the United States Toxic Substances Control Act (TSCA) was the perception that little was known about the risk to human health and the environment for the majority of chemicals in commerce. It was based on the fact that approximately 62,000 of the greater than 85,000 substances on the TSCA inventory at the time were added during the original inventory compilation in 1978–79 without a risk evaluation (known as “existing substances”). A major flaw in ‘old TSCA’ was that it was extremely difficult for the US Environmental Protection Agency (USEPA, the Agency) to take substantive action on existing substances, even those with well-known risks (e.g. asbestos).
The Frank R. Lautenberg Chemical Safety for the 21st Century Act (LCSA) aimed to correct this deficiency, directing the Agency to systematically prioritize existing chemicals for evaluation and, if necessary, apply risk management measures up to and including an outright ban. Initially it seemed that this component of LCSA would have the most significant effect on the chemical industry. However, as it turns out, the changes in the assessment of ‘new’ substances that many thought were simple updates to the Section 5 language have had a much more immediate impact. This article will focus on the regulatory treatment of new substances under revised TSCA and will offer suggestions on how to develop a robust Premanufacture Notice (PMN).
LCSA has not changed the process for new chemical risk assessment, but it has incorporated several new concepts that have affected the outcome of the process.
- If the substance “may present unreasonable risk” and/or there is “insufficient information to make a determination”, the Agency must now regulate the substance or ban commercialization.Previously USEPA could only justify regulation when potential unreasonable risk could be substantiated, but now “insufficient information” in and of itself may be used as the basis for regulation.The additional information that might be required to meet the “sufficient” standard could involve testing to better define the hazard, but in many cases the Agency is requiring more detailed information on chemical operations and uses to better understand potential human exposures and environmental releases.
- The use(s) of the PMN substance identified in the submission remain the focus of the risk assessment.However, other “reasonably foreseen” uses not intended by the submitter may now be included in the assessment and can increase the chances of a finding of unreasonable risk.
- In addition, any “potentially exposed susceptible subpopulation" that may be at greater risk than the general population from exposure to the chemical must also be considered (e.g., infants, children, pregnant women, workers, and the elderly).While consumer uses always received more rigorous scrutiny than industrial uses, the lower acceptable exposure limits for infants and the elderly for example can greatly increase the possibility that potential exposures might result in a finding of unreasonable risk.
Prior to a new substance being allowed into commerce the Agency must publish affirmation that the substance “is not likely to present an unreasonable risk” along with the basis for the finding. If risks are identified but can be controlled USEPA must issue a regulation (e.g., a Consent Order and/or a Significant New Use Rule) that includes mandatory management measures to mitigate the risks before commercialization. Incorporation of the concepts mentioned above into the new chemical review has resulted in a significant shift in the outcomes of US new chemical assessments. As a result, the percentage of submissions allowed without restriction has decreased from an average of 87% prior to LCSA enactment (Figure 1) to 31% (Figure 2). A significantly higher percentage of PMNs are now subject to regulatory action or are withdrawn.
In order to maximize the chance of a successful PMN outcome it is essential to inform the risk assessment by assuring that the hazard and exposure information provided (including environmental release) are as thorough as possible. The exposures and releases described must cover the entire lifecycle of the substance in question, namely from the moment the substance is created to the time it no longer ‘exists’ (e.g. is converted into another substance or is ultimately disposed). While generally not an issue when all manufacture and use sites are under the control of the submitter, the weakest component of most submissions is frequently the information on human exposures and environmental releases for downstream processing and use at sites either not currently known (markets still developing) or not under the control of the submitter. As the substance moves through the value chain to processers and end users, the available data typically becomes less and less granular. In the absence of sufficient exposure and release data, or to supplement the information provided by the PMN submitter, the Agency uses exposure models and generic use scenarios that incorporate conservative assumptions. This increases the probability of a “may present unreasonable risk” determination. To make the likelihood that information submitted is used in the assessment, detailed descriptions of operations and uses should be provided, always considering:
- How many people are exposed?What form is the chemical in? How often?For how long?If exposure is mitigated by extraneous factors, they should be described in detail (e.g. personal protective equipment for workers, ventilation).This is a particular challenge for consumer uses, often resulting in extremely conservative assumptions.
- How much is released to the environment from manufacture and use? How often?This includes equipment cleaning and transport containers.If released to water is there waste treatment prior to release?What is the efficiency of removal?If the substance is landfilled what is the location?Is the landfill lined?If there are releases to air what type of air pollution control technologies are used?If fugitive emissions are possible who is likely to be exposed?
Information for potential consumer exposure should include a detailed description of the types of products or articles that will incorporate the substance, the function of the substance in the products, the quantity in each formulation and a description of how and where the products would be used including information regarding consumption rates, frequency and duration of use. Here it is essential to consider any “potentially exposed susceptible subpopulation", especially infants and children. The route of exposure is also germane, i.e. the Agency is particularly concerned about the potential for lung toxicity from inhalation of respirable particles and aerosols.
When information is not available for uses not under the control of the submitter, one possibility is to ask the downstream user to supply the detailed exposure and release data for inclusion in the submission. If the downstream user has concerns about release of confidential business information (CBI), this information can be supplied directly to USEPA through a separate letter of support assuring that the CBI data is protected.
Representative data obtained under actual conditions is always preferable to estimates, but models can provide useful exposure and fate estimates where data gaps exist. The Agency provides a wealth of models and other tools to assist in generating these estimates. However, it is important to understand the limitations, default values, and embedded assumptions when using these models. Ultimately, to be useful in a risk assessment, the quantitative exposure information (concentrations or doses) must be compared to the toxicological endpoints associated with the hazards that are identified. In conjunction with the physical property, fate and toxicological information relevant to the substance (measured, estimated or read-across) these estimates of exposure and release allow the submitter to replicate the PMN assessment process and predict the potential regulatory outcome.
Changes to the PMN risk assessment under LCSA pose a challenge to submitters, but forewarned is forearmed. To avoid extensive delays and the potential for an undesirable outcome it is essential to determine whether sufficient information is included with the notice for the Agency to make a quantitative determination of risk from exposures and releases during the lifecycle of the substance. A proactive screening risk assessment prior to submission would help submitters anticipate regulatory actions or concerns and plan accordingly.
You can listen to Kelly Mayo, Senior Regulatory Scientist at knoell USA, talk about Understanding the Paradigm Shift in the US New Chemicals Program and Importance of Supply Chain Communication at SOCMA Week this December.
Join the Policy Track on Thursday 5th December at 2:10 pm to hear more!
Jeffrey Hafer and Kelly Mayo, Senior Regulatory Scientists at knoell USA
Jeffrey Hafer and Kelly Mayo, Senior Regulatory Scientists at knoell USA