On 4 November 2019, the United States Environmental Protection Agency (EPA) announced the availability of the draft risk evaluation for N-methylpyrrolidone (NMP), which includes more than 30 uses of NMP in adhesives, sealants, paints and arts and craft paints, paint and coating removers, adhesive removers, and degreasers. In the draft risk evaluation, EPA has made a preliminary determination that NMP does not present risks to the environment, bystanders, or occupational non-users (ONU). Additionally, the draft risk evaluation discusses how workers and consumers could be adversely affected by NMP under certain conditions of use. EPA notes that as with any chemical product, it strongly recommends that users carefully follow all instructions on the products label. EPA will publish a Federal Register notice announcing the availability of the draft risk evaluation and beginning a 60-day comment period. The draft risk evaluation will be peer reviewed by the Toxic Substances Control Act (TSCA) Science Advisory Committee on Chemicals (SACC) on 5-6 December 2019. EPA requests comments on the draft risk evaluation by 26 November 2019, to allow SACC time to review and consider them before the peer review meeting. EPA states that it will use feedback received from the public comment and peer review processes to inform the final risk determinations.
TSCA Section 6, as amended by the Frank R. Lautenberg Chemical Safety for the 21st Century Act (Lautenberg Act), requires EPA to conduct risk evaluations to determine whether a chemical substance presents an unreasonable risk of injury to health or the environment, without consideration of costs or other non-risk factors, including an unreasonable risk to a potentially exposed or susceptible subpopulation identified as relevant to the risk evaluation by the Administrator, under the conditions of use. The statute identifies the minimum components EPA must include in all risk evaluations. For each risk evaluation, EPA must publish a document that outlines the scope of the risk evaluation to be conducted, which includes the hazards, exposures, conditions of use, and the potentially exposed or susceptible subpopulations that EPA expects to consider. Each risk evaluation must also: (1) integrate and assess available information on hazards and exposures for the conditions of use of the chemical substance, including information on specific risks of injury to health or the environment and information on relevant potentially exposed or susceptible subpopulations; (2) describe whether aggregate or sentinel exposures were considered and the basis for that consideration; (3) take into account, where relevant, the likely duration, intensity, frequency, and number of exposures under the conditions of use; and (4) describe the weight of the scientific evidence for the identified hazards and exposure. The risk evaluation must not consider costs or other non-risk factors.
Draft Risk Evaluation for NMP
The draft risk evaluation states that NMP is widely used in the chemical manufacturing, petrochemical processing, and electronics industries. According to the draft risk evaluation, there is also growing demand for NMP use in semiconductor fabrication and lithium ion battery manufacturing. In the commercial sector, NMP is primarily used for producing and removing paints, coatings, and adhesives. Other applications include, but are not limited to, use in solvents, reagents, sealers, inks, and grouts. The risk evaluation states that EPA evaluated the following categories of conditions of use for NMP: manufacturing; processing; distribution in commerce; industrial, commercial, and consumer uses; and disposal. The total aggregate production volume for NMP decreased slightly from 164 to 160 million pounds between 2012 and 2015.
Environmental Unreasonable Risks
For all conditions of use, the draft risk evaluation states that EPA did not identify any scenarios indicating unreasonable risk for aquatic, sediment-dwelling, or terrestrial organisms from exposures to NMP. According to the draft risk evaluation, NMP readily degrades under aerobic conditions and is not expected to persist in the environment. Because the respiratory quotient (RQ) values do not exceed 1, and because EPA used a conservative screening level approach, these values indicate that the risks of NMP to the aquatic organisms are unlikely. As a result, EPA does not find unreasonable risk to the environment for any of the conditions of use for NMP.
Unreasonable Risk to the General Population
The draft risk evaluation states that EPA is not including general population exposures in the risk evaluation for NMP. As explained in the Problem Formulation for the Risk Evaluation for NMP, EPA determined that general population exposures were outside the scope of the risk evaluation. According to the draft risk evaluation, EPA determined that the existing regulatory programs and associated analytical processes adequately assess and effectively manage the risks of NMP that may be present in various media pathways (e.g., air, water, land) for the general population. For these cases, the draft risk evaluation states that EPA believes that the TSCA risk evaluation should not focus on those exposure pathways, but rather on exposure pathways associated with TSCA conditions of use that are not subject to those regulatory processes, because the latter pathways are likely to represent the greatest areas of concern to EPA.
Unreasonable Risk to Workers
According to the draft risk evaluation, EPA evaluated workers acute and chronic inhalation and dermal exposures (including uptake of vapor through skin) for non-cancer risks and determined whether any risks indicated are unreasonable risk. The draft risk evaluation states that [t]he drivers for EPAs determination of unreasonable risk for workers are reproductive effects from chronic inhalation and dermal exposures; generally, risks identified for workers are linked to chronic exposures. The determinations reflect the severity of the effects associated with occupational exposures to NMP and incorporate consideration of expected personal protective equipment (PPE) (frequently estimated to be gloves with a protection factor of 5, 10, or 20). For workers, EPA determined that the conditions of use that presented unreasonable risks included processing of NMP into formulations or mixtures, and many industrial or commercial uses as a solvent or degreaser.
Unreasonable Risk to ONUs
According to the draft risk evaluation, EPAs exposure assessment includes estimates of NMP exposures to ONUs. ONUs are located in the general vicinity near workers but are further from emissions sources. Unlike workers, ONUs do not have direct dermal contact with liquids. The draft risk evaluation states that the estimates assume ONUs are not wearing respirators. While the difference between ONU exposures and workers directly handling the chemical generally cannot be quantified, according to the draft risk evaluation, EPA assumes that, in most cases, ONU inhalation exposures are expected to be lower than inhalation exposures for workers directly handling the chemical substance. To account for those instances where monitoring data or modelling did not distinguish between worker and ONU inhalation exposure estimates, the draft risk evaluation states that EPA considered the central tendency risk estimate when determining ONU risk. For several conditions of use, there were risks for ONUs for high-end chronic exposures. Risk estimates for ONUs for the central tendency scenarios did not indicate risk, however. EPA determined that the conditions of use assessed did not present an unreasonable risk for ONUs.
Unreasonable Risk to Consumers
EPA evaluated consumer acute inhalation, dermal, and vapor through skin exposures for non-cancer risks and determined whether the risks indicated are unreasonable. According to the draft risk evaluation, EPA evaluated risks for consumers using acute exposure scenarios. The driver for EPAs determination of unreasonable risk is developmental adverse effects from acute inhalation and dermal exposure. These adverse effects include foetal mortality. EPA determined that several consumer conditions of use present unreasonable risk of injury to health.
Unreasonable Risk to Bystanders (from Consumer Uses)
The draft risk evaluation states that EPAs exposure assessment includes estimates of NMP exposures to bystanders (i.e., those located in the house during consumer product use) who do not have direct contact with NMP-containing consumer products. EPA did not find unreasonable risk to bystanders for the conditions of use assessed.
It will take more time to digest EPAs 450-plus-page draft risk evaluation and the many supplemental documents associated with it. One item of particular interest is the occupational use scenarios that EPA has preliminarily concluded present an unreasonable risk. In reviewing those occupational applications, it appears that EPA has assumed the use of gloves with a protection factor of 10 for most, if not all, uses. Had the higher glove protection factor of 20 been used, several of the unreasonable risk findings would be negated. EPA states that it did not apply the higher glove protection factors for these uses because it found no information that would indicate specific training for glove use for those sectors. Even if a product label or safety data sheet (SDS) specified the use of a particular glove that was appropriate for NMP, EPAs risk evaluation assumes that such direction would be ignored. This assumption calls into question whether and/or how PPE and exposure control information stipulated on product labels and SDSs should be incorporated into an EPA evaluation and what role, if any OSHA Hazard Communications requirements will play. This is one of likely dozens of issues stakeholders can be expected to address during the comment period.
National Law Review, 5 November 2019