Risks posed by various components of hair dyes

Area of Science:

• Toxicology
• Chemical Risk Assessment
• Cosmetic Safety

Background:

• Hair dyes contain various chemicals with potential health risks.
• Previous risk assessments by regulatory agencies like the FDA and EPA have limitations.
• Animal bioassays provide data for evaluating chemical carcinogenicity.

Purpose of the Study:

• To calculate the carcinogenic risks associated with chemicals used in hair dyes.
• To compare these risks with established benchmarks, such as cigarette smoking.
• To evaluate risks using a comprehensive risk assessment methodology.

Main Methods:

• Utilized carcinogenic potency measures from National Cancer Institute (NCI) bioassays.
• Applied a risk assessment procedure similar to, but more complete than, FDA/EPA methods.
• Calculated risks based on exposure data for rats and mice.

Main Results:

• The highest risk from a discontinued hair dye was equivalent to smoking 6 cigarettes in a lifetime.
• The 95th percentile risk for this dye was equivalent to smoking 120 cigarettes in a lifetime (2 per year).
• Even using upper-bound estimates for untested chemicals, the overall estimated risk remained small.

Conclusions:

• Carcinogenic risks from hair dye chemicals, even historical ones, are relatively low.
• The employed risk assessment methodology offers a more complete evaluation than standard regulatory approaches.
• Further research may be warranted for untested chemicals, but current estimates suggest minimal risk.