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Does occupational exposure to organic solvents affect colour discrimination?
Richard B Lomax1, Peter Ridgway, Maureen Meldrum
1Field Operations Directorate CSD1, Health and Safety Executive, Bootle, Merseyside, UK. richard.lomax@hse.gsi.gov.uk
Toxicological Reviews
|December 8, 2004
Summary
Occupational exposure to organic solvents, particularly styrene, can impair colour discrimination, typically affecting blue-yellow vision. Evidence for other solvents like toluene and tetrachloroethylene is less conclusive, and mechanisms remain unclear.
Area of Science:
- Occupational Health
- Toxicology
- Neuroscience
Background:
- Occupational exposure to organic solvents is widespread.
- Potential neurotoxic effects, including impacts on sensory perception, are a concern.
- Colour vision impairment is a potential, subtle indicator of neurotoxicity.
Purpose of the Study:
- To review and assess the evidence on occupational organic solvent exposure and its effects on colour discrimination.
- To investigate exposure-response relationships and the reversibility of colour vision changes.
- To explore potential mechanisms and human health significance.
Main Methods:
- Systematic review of epidemiological studies on solvent-exposed workers.
- Analysis of data on styrene, toluene, tetrachloroethylene, and mixed solvent exposures.
- Evaluation of exposure levels, dose-response, and reversibility of effects.
Main Results:
- Robust evidence indicates styrene exposure impairs colour discrimination (tritan-type), with effects potentially occurring below 20 ppm (8 h TWA).
- Toluene shows no acute effect, but long-term impacts are inconclusive.
- Evidence for tetrachloroethylene and mixed solvents is limited and unreliable; styrene is the primary credible source of effect.
- Mechanisms are speculative, likely not involving ocular pathology or general CNS depression.
Conclusions:
- Styrene is confirmed to cause subtle impairments in colour discrimination.
- Data for other solvents are insufficient to draw firm conclusions.
- Colour vision changes are distinct from general neurotoxicity and not a reliable marker for other solvent-induced effects.