original abstract†Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.
BACKGROUND: It is widely accepted that there is a molecular weight (MW) cut-off of 500, such that single chemicals with MWs higher than 500 cannot be skin sensitizers. If true, this could serve as a useful principle for designing non-sensitizing chemicals. OBJECTIVES: To assess whether the 500 MW cut-off is a myth or a reality. METHODS: A database of 699 chemicals tested for skin sensitization in guinea pigs or mice was analysed to establish the number of tested chemicals with MW> 500, and to establish whether any of these were sensitizers. RESULTS: Only 13 (2%) of the 699 chemicals in the database have MW> 500. Of the 13 tested compounds with MW> 500 in the database, five are sensitizers and eight are non-sensitizers. CONCLUSIONS: The 500 MW cut-off for skin sensitization is a myth, probably derived from the widespread misconception that ability to efficiently penetrate the stratum corneum is a key determinant of sensitization potency. The scarcity of sensitizers with MW> 500 simply reflects the general scarcity of chemicals with MW> 500.
- “The 500 Dalton rule for the skin penetration of chemical compounds and drugs,” J D Bos and M M Meinardi, Exp Dermatol, 2000.
- “Determinants of skin sensitisation potential,” David W Roberts and Aynur O Aptula, J Appl Toxicol, 2008.
One article on PainScience.com cites Roberts 2013 as a source:
- PS Does Epsom Salt Work? — The science of Epsom salt bathing for recovery from muscle pain, soreness, or injury
This page is part of the PainScience BIBLIOGRAPHY, which contains plain language summaries of thousands of scientific papers & others sources. It’s like a highly specialized blog. A few highlights:
- A Bayesian model-averaged meta-analysis of the power pose effect with informed and default priors: the case of felt power. Gronau 2017 Comprehensive Results in Social Psychology.
- The neck and headaches. Bogduk 2014 Neurol Clin.
- Agreement of self-reported items and clinically assessed nerve root involvement (or sciatica) in a primary care setting. Konstantinou 2012 Eur Spine J.
- Effect of NSAIDs on Recovery From Acute Skeletal Muscle Injury: A Systematic Review and Meta-analysis. Morelli 2017 Am J Sports Med.
- Association of Spinal Manipulative Therapy With Clinical Benefit and Harm for Acute Low Back Pain: Systematic Review and Meta-analysis. Paige 2017 JAMA.