Science
Mechanism of Action
As a pyrethroid insecticide, resmethrin acts as a neurotoxin by disrupting the normal functioning of the insect nervous system, leading to paralysis and eventual death. For humans, direct skin contact can induce symptoms such as stinging, burning, itching, tingling, and numbness, indicative of its impact on nerve endings.
Research
Clinical Evidence
Insufficient-data confidenceN/A
Key findings
- 01 In a patch test involving 230 non-atopic volunteers, 5% resmethrin elicited irritant reactions in two individuals.
Transparency
Dusting Analysis
Resmethrin is an insecticide not approved for cosmetic use, therefore, the concept of 'dusting' (over-marketing or misuse) in skincare formulations is not applicable.
The Formula
Formulation
Stability
The compound exhibits stability under heat and oxidation but undergoes rapid decomposition when exposed to air and light, though more slowly than natural pyrethrins. It is unstable in alkaline environments. Degradation by hydrolysis is not efficient, with a half-life exceeding 89 days within the pH range of 5 to 9.
Conflicts
- Alkaline media
- Strong oxidizers
- Lime
- Ordinary soaps
Safety
Safety Profile
Resmethrin is an insecticide and is not approved for cosmetic use. The U.S. Environmental Protection Agency (EPA) classified it as 'likely to be carcinogenic to humans' based on some evaluations, although other long-term feeding studies did not corroborate carcinogenicity. All resmethrin products in the U.S. were voluntarily cancelled by registrants after December 31, 2015. It is designated a Restricted Use Pesticide due to its toxicity to fish. The California Safe Cosmetics Program identifies resmethrin as a reportable ingredient due to hazard traits including carcinogenicity, developmental toxicity, endocrine toxicity, environmental toxicity, and reproductive toxicity.
Your Skin
Skin Compatibility
Our Assessment
Verdict
Resmethrin is a highly toxic insecticide with significant safety concerns, including potential carcinogenicity, developmental, and reproductive toxicity, making its use in any skincare product entirely unacceptable and harmful.
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References
Sources