The US EPA is exploring how to factor "practicability" into its derivation of occupational exposure limits for TSCA risk management rules, an agency official has said.
The plans, however, are raising questions about how much flexibility the EPA has to change an existing chemical exposure limit (ECEL) between floating it during risk evaluation and adopting it as a regulatory measure in a final TSCA section 6(a) rule.
The EPA’s Eileen Murphy offered insights into the agency’s ECEL approach at the American Chemistry Council (ACC)’s GlobalChem conference last month. Her presentation came just days after the EPA floated an occupational exposure limit for formaldehyde on par with background levels that can be found in the environment.
"Practicability is a factor that we can consider in risk management," said Dr Murphy, director of the EPA’s existing chemicals risk management division.
If an occupational exposure level developed in the risk evaluation is below an analytical detection level, for example, the agency can consider that in establishing an ECEL in the risk management stage, she said. "We’re exploring that currently, because we're running into it now, and we're certainly going to run into it later."
Dr Murphy’s remarks expanded on testimony Michal Freedhoff provided to Congress in January. The head of the EPA’s chemicals office told lawmakers that the agency has flexibility to deviate from an ECEL derived during a risk evaluation.
"In the risk evaluations, we're not supposed to be considering costs or other non-risk factors. When we write rules, we 100% consider those things," Dr Freedhoff said.
"If we get a draft risk evaluation that leads to a math outcome that the draft proposed occupational safety limit is below background levels for that chemical, we'll say very clearly in the draft risk evaluation that that number won't be the basis of our rule," she told Congress.
Approach ‘never permitted’
Some environmental and health advocates, however, are pushing back on the approach.
"Setting an ECEL above the exposure level that EPA has found to cause or contribute to unreasonable risk is never permitted under TSCA," said Jonathan Kalmuss-Katz, supervising senior attorney with environmental law firm Earthjustice.
In a scenario where an ECEL is infeasible because it is below background levels or lower than analytical detection limits, "the answer is not to increase the ECEL, worker safety be damned", he said. Instead, the EPA should select a more effective risk management response, like phasing out that use of the chemical.
Maria Doa, senior director of chemical policy for the Environmental Defense Fund (EDF) and a 30-year EPA veteran, offered a similar view.
"Adopting an ECEL in risk management that is less protective than the ECEL developed as part of the risk evaluation would not address the unreasonable risk as required under TSCA section 6(a)," she said.
The Congressional mandate to consider costs and alternatives during risk management should be factors for selecting between regulatory instruments, Dr Doa said. For example, the agency may consider the feasibility of achieving an ECEL when deciding between a ban, a worker protection programme (WCPP) or a combination of restrictions, she said.
Those non-risk considerations, however, "do not give EPA the discretion to dismiss the unreasonable risk as part of the risk management action", she said.
Agency flexibility
Industry representatives, however, say that a health-protective exposure level calculated during risk evaluation does not need to match a regulatory limit.
Paul DeLeo, senior director at the ACC, said the ECELs developed during risk evaluation are based on generic worst-case assumptions and conservative toxicity values.
The agency has "flexibility going from that health-based number to a regulatory compliance number", Dr DeLeo said.
His colleague, Karyn Schmidt, added that it is not clear if an ECEL calculated during risk evaluation is meant to equate to a ‘no unreasonable risk’ threshold.
A health-based value "may overshoot the ‘no unreasonable risk’ line, in which case the real reasonable risk line is different when you get to risk management", she said.
More fundamentally, an exposure limit set so low that it cannot be detected or is below background levels "creates nonsensical, if not impossible, results", said Schmidt. When the air contains natural levels of a substance below its ECEL "it makes it impossible to regulate", she said.
Attorneys at Keller and Heckman agreed the agency has room to manoeuvre.
"Given the extreme uncertainty in EPA’s unreasonable risk determinations, EPA could set the ECEL in a more realistic direction," said Herb Estreicher, David Fischer and James Votaw.
The EPA also needs to define, or "at least put boundaries", on what does and does not constitute ‘unreasonable risk’ under the law, the Keller and Heckman attorneys said.