1,1-Dimethylhydrazine: MAK Value Documentation, addendum - Translation of the German version from 2021

Area of Science:

• Occupational toxicology
• Chemical risk assessment
• Carcinogenesis and mutagenesis

Background:

• 1,1-dimethylhydrazine (DMH) is a chemical compound with known toxicological properties.
• Previous assessments by the MAK Commission have identified potential health hazards.
• Re-evaluation was necessary considering all available toxicological data.

Purpose of the Study:

• To re-evaluate the occupational exposure limit value (MAK value) for 1,1-dimethylhydrazine.
• To assess all toxicological endpoints, including acute and chronic toxicity, carcinogenicity, genotoxicity, and skin/eye irritation.
• To determine appropriate hazard classifications and designations.

Main Methods:

• Comprehensive literature search to identify relevant toxicological studies.
• Analysis of data on acute toxicity, target organ toxicity after subchronic and chronic exposure.
• Evaluation of carcinogenicity studies in rats, mice, and hamsters following different exposure routes.
• Assessment of genotoxicity data (in vitro and in vivo).
• Review of skin and eye irritation studies, dermal absorption potential, and sensitization data.

Main Results:

• DMH causes acute central nervous system effects via GABA depletion.
• Target organs identified include blood, liver, nervous system, colon, spleen, nose, lungs, gall bladder, pituitary gland, pancreas, thyroid, blood vessels, kidneys, and nasal mucosa.
• DMH is classified as a Carcinogen Category 2 and Germ Cell Category 3A due to tumor induction and genotoxic effects.
• The 'H' designation for dermal absorption and 'Sh' for skin sensitization are retained.
• No MAK value can be derived due to significant health risks.

Conclusions:

• 1,1-dimethylhydrazine poses significant carcinogenic and genotoxic risks.
• Its toxicity profile prevents the establishment of a safe occupational exposure limit.
• The substance requires stringent handling precautions due to dermal absorption and potential sensitization.