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epidemiological data
Type of information:
experimental study
Adequacy of study:
supporting study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Published in peer reviewed literature and quoted in EU transitional RAR (EU, 2008) for styrene.

Data source

Reference Type:
Intervention study on acquired color vision deficiencies in styrene-exposed workers.
Triebig G, Stark T, Ihrig A and Dietz MC
Bibliographic source:
J Occup Environ Med, 43, 494-500.

Materials and methods

Study type:
other: Intervention study
Endpoint addressed:
repeated dose toxicity: inhalation

Test material

Constituent 1
Chemical structure
Reference substance name:
EC Number:
EC Name:
Cas Number:
Molecular formula:


Type of population:
Ethical approval:
not specified
Details on study design:
The study examined the colour vision of workers from a boat manufacturing plant. 22 were exposed to styrene and 11 were controls from the same plant.
Exposure assessment:
Details on exposure:
PHASE 1 Examinations were performed: Monday morning and Thursday afternoon of the first week and before and immediately after a vacation of 4 weeks (phase 1),
PHASE 2 The examinations were repeated approximately 10 months later after the exposure level of styrene had been reduced.

Styrene uptake was estimated by biological monitoring. The metabolites mandelic acid and phenylglyoxcylic acid were measured in urine samples taken on Thursday afternoon.

Results and discussion

PHASE 1 In both Thursday examinations, styrene-exposed workers had higher colour confusion index (CCI) values compared with controls, indicating quantitative colour vision loss. After the 4 week holiday where there was no styrene exposure, a significant decrease of CCI values to normal range was found in workers exposed to styrene.

PHASE 2 Reexamination after 10 months also showed also lower CCI values in exposed workers, indicating a dose-effect relationship. It was noted that abnormal CCI values occurred primarily in subjects with an excretion of approximately 500 to 600 mg mandelic acid plus phenylglyoxcylic acid (measured metabolites of styrene) per gram creatinine or more.

It was concluded that styrene-induced colour vision dysfunction is reversible after an exposure-free interval of 4 weeks.

Strengths and weaknesses:
As a single colour vision test rather than a testing battery approach was used, these findings are not sufficiently robust to reliably characterise the scale and the nature of the effect.

Applicant's summary and conclusion

Colour confusion index as a measure of colour vision was impaired primarily in subjects with an excretion of approximately 500 to 600 mg mandelic acid plus phenylglyoxcylic acid (measured metabollites of styrene) per gram creatinine or more. The EU transitional RAR (EU, 2008) equated this to a NOAEC of 50 ppm (8-hr TWA). Styrene-exposed workers making errors in colour discrimination tests were not aware of any deficit. Effects on colour discrimination were fully reversible within weeks following cessation of exposure, and showed significant improvement after an exposure-free weekend.
EU (2008). Annex XV Transitional Dossier: Styrene.