Styrene

Epidemiological data

Administrative data

Endpoint:

epidemiological data

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Acceptable, well-documented publication meeting basic scientific principles.

Data source

Reference

Reference Type:

publication

Title:

Risk of cancer in workers exposed to styrene at eight British companies making glass-reinforced plastics

Author:

Coggon, D., Ntani, G., Harris, E. C., and Palmer, K. T.

Year:

2015

Bibliographic source:

Occup Environ Med 2015;72:165-170

Materials and methods

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:

ethenylbenzene

Method

Type of population:

occupational

Details on study design:

The risk of lymphohaematopoietic (LH) and other cancers associated with styrene was investigated. To this end, a cohort assembled in the 1980s of workers exposed to styrene in the British glass-reinforced plastics (GRP) industry was extended to the end of 2012.
7970 workers at 8 companies in England which used styrene in the manufacture of glass-reinforced plastics were examined. Mortality was compared with that for England and Wales. A supplementary nested case-controll study compared styrene exposures, lagged by 5 years, in 122 incident or fatal cases of LH cancer and 1138 matched controls.

Details on exposure:

Jobs were classified to four categories according to the potential for exposure to styrene: high (hand laminators), moderate (people who regularly entered areas of GRP production or worked close to laminating operations), low (people who occasionally entered areas of GRP production or experienced a constant but low-level exposure at a situation remote from laminating operations), and back-ground (all other jobs).
Measurements at 5 of the factories after 1975 indicated that the high exposure category corresponded to an 8-h time-weighted average exposure of 40-100 ppm.

Statistical methods:

Statistical analysis was carried out with Stat V.13 software (StatCorp. College Station, Texas, USA). The mortality of cohort members was compared with that of the national population of England and Wales by the person-years method, with expected numbers of deaths calculated for combinations of sex, 5-year age band and 5-year calendar period (except for deaths during 2010-2012, for which rates during 2005-2012 were applied). Each person was considered to be at risk from the latest of (1) his/her date of first employment; (2) the date from which employees at the relevant company were eligible for inclusion in the cohort; and (3) the date when he/she first entered the category of exposure under consideration. H/she then remained at risk until the earliest of: (1) death; (2) loss from
follow-up for other reasons (eg, emigration); (3) 31 Decemher 2012; and (4) (only in analyses by level of exposure) moving to a higher exposure category. Results were summarised by SMRs with associated 95% CIs.
To explore risks of lymphohaematopoietic (LH) cancer further, a nested case-control analysis was also carried out, in which cases were identified not only from certified underlying causes of death, but also from cancer regisrrarions and contributing causes of death. A prescribed algorithm was used to match each case wich up to 10 controls of the same sex, who worked at the same factory, were under follow-up at the date of diagnosis of the case (ie, the first date at which the case was known to have LH cancer), and were born within 2 years of the case. Associations with level of exposure to styrene, lagged by 5 years, were assessed by conditional logistic regression, and summarised by ORs.

Results and discussion

Results:

By the end of 2012, 1321 cohort members had died, 3935 were still alive, and 914 had been lost to follow-up.
No elevation from lymphohematopoetic cancer was observed for the full cohort (SMR 0.90; 95% CI 0.69-1.15) or in those with more than background exposure to styrene (SMR 0.82; 95% CI 0.58-1.14) and no association was found in the case-control part. For workers with estimated high exposures (40-100 pp, 8h TWA, for >1year) the OR was 0.54 (95% CI 0.23-1.27). Mortality from lung cancer was significantly increased (SMR 1.44; 95% CI 1.10-1.86). To the conclusion of the authors, this latter finding, as not being supported by other epidemiology studies, may have been confounded by smoking what would be worth further checking.