Skin notation in the context of workplace exposure standards

Area of Science:

• Occupational Health
• Toxicology
• Industrial Hygiene

Background:

• Workplace exposure standards incorporate
• skin notation
• to account for potential cutaneous absorption of substances.
• The ACGIH (1986) documentation for Threshold Limit Values (TLVs) assigned
• skin notation
• to 91 of 168 substances, primarily based on dermal lethal dose to 50% (LD50) or human data.
• A significant portion of these notations lack clear scientific justification, relying on undocumented statements, observed skin effects, or analogy.

Purpose of the Study:

• To evaluate the scientific basis for
• skin notation
• assignments in workplace exposure standards.
• To highlight inconsistencies in the application of dermal absorption data for setting Threshold Limit Values (TLVs).

Main Methods:

• Analysis of the ACGIH (1986) documentation for
• skin notation
• assignments.
• Categorization of the basis for
• skin notation
• (e.g., LD50, human data, undocumented statements, skin effects, analogy).
• Examination of the consistency in applying the established
• cut-off
• value for dermal absorption.

Main Results:

• Dermal lethal dose to 50% (LD50) or human data supported
• skin notation
• for 91 substances.
• For 55 substances (32.7%), the basis for
• skin notation
• was unclear, including undocumented statements (14.5%), skin effects (8%), analogy (4%), or lacking reference (20%).
• The established
• cut-off
• value of 2 g/kg for dermal absorption was inconsistently applied.

Conclusions:

• The scientific justification for many
• skin notation
• assignments is questionable, potentially affecting the validity of Threshold Limit Values (TLVs).
• Inconsistencies in applying dermal absorption data and the
• cut-off
• value necessitate a more rigorous and transparent approach.
• Full examination and citation of scientific data are recommended for establishing TLVs for substances with cutaneous absorption potential.