CPSC finalizes new definition for "strong sensitizer."

Last week, the U.S. Consumer Product Safety Commission (CPSC or the Commission) released a Final Rule changing the supplemental definition for “strong sensitizer” under the Federal Hazardous Substances Act (FHSA), which requires appropriate cautionary labeling on certain hazardous household products. The revised definition becomes effective March 17, 2014.

The FHSA defines “strong sensitizer” as “a substance which will cause [a hypersensitivity] on normal living tissue through an allergic or photodynamic process.” The CPSC promulgated a supplemental definition in a 1986 rule. In 2005, the Commission initiated an extensive process to update the definition, first convening a panel of scientific experts to make recommendations to CPSC staff, and then developing a draft technical report that underwent federal agency and external scientific peer review. A Notice of Proposed Rulemaking and accompanying guidance document (Strong Sensitizer Guidance) were published together on March 12, 2013.

The new supplemental definition of “strong sensitizer” aims to bring the definition in better alignment with current science on sensitization. According to the CPSC, the revised definition:

  • eliminates redundancy;
  • removes certain subjective factors;
  • incorporates new and anticipated technology;
  • ranks the criteria for classification in order of importance;
  • defines criteria for “severity of reaction”; and
  • provides for a “weight-of-evidence” approach to determining whether a substance qualifies as a strong sensitizer.

In promulgating the new definition, the CPSC addressed several comments, summarized as follows:

Implementing GHS would be too far-reaching. Two commenters urged the Commission to implement the Globally Harmonized System of Classification and Labelling of Chemicals (GHS). The Commission clarified that GHS is not a standard-setting regulatory scheme but a set of criteria for classifying and communicating hazards. Moreover, CPSC stated that implementing GHS “would be broad-reaching, with potential impact beyond the FHSA,” and is far beyond the scope of the rulemaking.

No far-reaching effects. The CPSC rejected one commenter’s assertion that the revised definition would have “far-reaching effects,” since substances would still be subject to case-by-case hazard assessments which incorporate an approach based on science and risk.

No differentiation needed for different allergy types. The CPSC acknowledged a commenter’s recommendation to address Type I and Type IV allergies separately, but argued that this would make the definition “significantly and unnecessarily more complex.” Instead, the Commission posited that the criteria in the definition is sufficiently flexible to assess all types of allergic reactions without specifically differentiating them, and that the Strong Sensitizer Guidance released last year would provide further assistance in evaluating substances.

QSAR data accepted but not prioritized. The Commission emphasized that data from Quantitative Structure-Activity Relationship (QSAR) models was specified in the rule as a factor to be considered in a weight-of-evidence analysis of whether a substance has significant potential for causing hypersensitivity. However, QSAR data would not be given precedence over “high-quality human and animal data.”

Consumer incident reports may be considered. One comment urged including the CPSC’s and manufacturers’ records of incidents of hypersensitivity as factors to be considered in determining a substance’s ability to cause hypersensitivity. In response, the Commission emphasized that the revised definition includes “case histories” as a factor, which encompasses consumer-submitted incident reports received by the manufacturer or CPSC. The CPSC will also consider revising the Strong Sensitizer Guidance to elaborate on “the types and sources of incident reports” to use in determining whether a substance is a “strong sensitizer.”

The CPSC also defended and maintained the proposed order of ranked data criteria; changed the potential “clinically important reaction” of “substantial physical discomfort or distress” to “substantial physiological effects, such as discomfort and distress,” for purposes of clarity; and made other minor drafting changes.

Analysis: The “strong sensitizer” definition in the Final Rule does not significantly deviate from the revision proposed last year, so there is not much unexpected here. Moreover, a substance will, as before, have to undergo an individualized evaluation by the CPSC as to whether it can cause hypersensitivity and be determined to be a “strong sensitizer.” The CPSC’s possible revision of the Strong Sensitizer Guidance to address consumer incident reports will be an issue to keep an eye on.