A critical review and meta-analysis of epidemiology studies of occupationally exposed styrene workers evaluated for chromosomal aberration incidence

Abstract Chromosome aberrations in the peripheral blood lymphocytes of styrene exposed workers have been suggested as a potential early marker for cancer risk. We performed a critical review and abstracted data from all studies using current chromosome aberration scoring criteria and providing at least a mean and standard deviation or standard error for the exposed and comparison groups. Using these data, we conducted a meta-analysis of occupational styrene exposed workers and incidence of chromosome aberrations. Our meta-analysis used the standardized mean difference as the summary statistic since all studies assess the same outcome but use different comparison populations. The primary meta-analysis of the 20 comparisons of 505 styrene exposed workers to 532 comparison workers found a meta-mean difference of 0.361 (95% CI -0.084 to 0.807, random effects model), but there was substantial lack of consistency across studies (I2 of 90.11, p-value