English summary
Occupational exposure to potentially hazardous agents may increase the risk of spontaneous abortion. The present study addresses the frequency and risk for miscarriage among dental surgeons compared to those of high-schoolteachers and non-employed women. A self-administered postal questionnaire was mailed to all dental surgeons registered in the Norwegian Dental Association (n=1320), and to a random sample of high schools teachers(n=1084), recruited from the registry in the Norwegian Educational Association. The data were collected retrospectively comprising the reproductive and occupational history of the female. The occupational exposure was addressed by a thorough examination of the work performed in the time when the couple tried to conceive and the woman became pregnant for her first time. The use of mercury containing dental amalgam, chloroform based rootcanal sealer, ethanol based disinfectant containing benzene, and other organic solvents was addressed in detail. Nitrous oxide sedation had not been used in dental surgeries in Norway when the survey was undertaken. The study was approved by the National Committee for Research Ethics and the Data Inspectorate in Norway. As not all women were working at the time when they became pregnant, the study population was subdivided into dental surgeons (n=727), high-school teachers (n=340) and group of homemaking women (n=300). On the average, 9.2% of the primiparous women had a spontaneous abortion. In the time period 1951-1990, the incidence of miscarriage increased from 5.3% to 11.5% for the study population. There was a significant correlation between outcome of pregnancy and time to pregnancy. Spontaneous abortion occurred twice as often in women who had a waiting time to pregnancy of nine months or more compared to women having shorter waiting time.The risk for spontaneous abortion among practising dentists in total was the same as for homemakers and teachers. In the age group past 30 years the dentists had a 2.4 times higher odds ratio (95% confidence interval:1.0–5.4) than teachers but it was not possible to link this to a specific occupational exposure. Exposure to mercury from the use of dental amalgam, to ethanol based disinfectant containing 0.25% benzene or to other solvents did not increase the risk.
Reference
Risiko for spontanabort blant førstegangsfødende tannleger
Dahl JE, Sundby J.
Norsk Epidemiologi 1999; 9: 51-55.