Risk of spontaneous abortion and maternal exposure to organic solvents in the shoe industry

Object: A high risk of spontaneous abortion was observed in women exposed to organic solvents during pregnancy. Since this risk was not found in the shoe industry, where these solvents are widely used, we carried out a case-control study on the risk of spontaneous abortion in a health district (Veneto, Northern Italy) where about 8,000 people work in shoe manufacturing. Aliphatic hydrocarbons were generally used; their concentrations were repeatedly below the mixture TLVs in the observation period. Methods: Cases (clinically recognized spontaneous abortion, ICD codes 632-634-636) and age-/year-/residence-matched controls (admitted for normal delivery) were traced in the files of the regional hospital discharges register. Data on 108 cases (81% response) and the same number of reference subjects were collected on questionnaires completed by nurses trained in occupational medicine. There were questions on confounding and occupational factors, and an open question to ensure a complete description of work done during pregnancy. An occupational physician, working blind, then coded exposure to organic solvents according to a three-level polytomous variable (no, low, high exposure). Results: The cases/controls not exposed, exposed to low levels and exposed to high levels of organic solvents were 78/88, 12/12, and 18/8 respectively. Adjusted for the confounding factors, the relative risk (RR) of spontaneous abortion for high exposure to organic solvents during pregnancy was 3.85, with 95% confidence intervals (CI) ranging from 1.24 to 11.9. RR was 1.58 (CI = 0.62-4.06) in women exposed to low solvent concentrations. Conclusions: Our results support the hypothesis that spontaneous abortion may be an adverse effect of exposure to high levels of organic aliphatic solvents in women employed in shoe manufacture.