Review of the epidemiological evidence relating toluene to reproductive outcomes

This review examines the epidemiological evidence for adverse reproductive outcomes from those occupational studies that present toluene-specific findings. Clinical investigations of the reproductive effects of toluene abuse are also examined. Six occupational studies reported associations between toluene and spontaneous abortion, two between toluene and congenital malformation, and three between toluene and reduced fertility. The spontaneous abortion studies provided the most suggestive evidence for an association with toluene. However, the potential for bias in some of these studies, the relatively homogeneous nature of the populations examined (e.g., four of the six studies evaluated similar groups of Finnish workers), and the multiple chemicals to which most workers were simultaneously exposed suggest cautious interpretation of these findings. Also, spontaneous abortion has generally not been observed as a major problem among highly exposed women who abuse toluene during pregnancy. The results of the occupational studies should be considered "hypothesis generating". Truly prospective studies with individually monitored data on toluene exposure and early fetal loss are needed to more definitively investigate this issue.