Solvent naphtha (coal), xylene-styrene cut

Epidemiological data

Administrative data

Endpoint:

epidemiological data

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

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

Reference Type:

publication

Title:

Intervention study on acquired color vision deficiencies in styrene-exposed workers.

Author:

Triebig G, Stark T, Ihrig A and Dietz MC

Year:

2001

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

Test material information

Constituent 1

Reference substance name:

Styrene

EC Number:

202-851-5

EC Name:

Styrene

Cas Number:

100-42-5

Molecular formula:

C8H8

IUPAC Name:

styrene

Method

Type of population:

occupational

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:

measured

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

Results:

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

Conclusions:

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.
Reference
EU (2008). Annex XV Transitional Dossier: Styrene. echa.europa.eu/doc/trd_substances/styrene/RAR/trd_rar_uk_styrene.rtf