This study was undertaken to examine whether occupational exposure to mercury amalgam and nitrous oxide influence reproductive events among women dentists. The reproductive events include time to pregnancy and spontaneous abortion, among other factors. Questionnaires concerning dental occupational exposure and reproductive health were mailed to a national sample of female dentists in the United States. Of the 3,621 respondents, 73 percent reported ever having been pregnant (2,643) and for 1,679, the most recent pregnancy occurred during a time period when they were working 30 or more hours per week in clinical dentistry. For each year assessed from 1970 to 1992, over half of the respondents who reported employment in clinical dentistry reported working with amalgam; and for a large portion of the period, about 90 percent of the dentists reported placing amalgams. Following dental school graduation, approximately 50 percent of the clinical dentists worked with nitrous oxide. This study suggests that exposures to nitrous oxide and mercury from amalgam occurs among the majority of female dentists. This study is likely to provide valuable information about reproductive outcome in women dentists with exposure to these workplace substances. Analysis of spontaneous abortion was conducted of a subgroup of the respondents who were working 30 or more hours per week in clinical dentistry and had complete data (1,329) using a gestational week based logistic regression model. The portion of the respondents with high amalgam exposure and high number of adverse work practices had 1.3 the likelihood of spontaneous abortion compared to those without amalgam exposure. The effect of five hours or more per week of nitrous oxide exposure was not altered by the use of scavenging equipment for the likelihood of spontaneous abortion with odds ratios of 1.2 for both scavenged and not scavenged exposure. Data suggest little, if any, alterations in risk of spontaneous abortion for the levels of exposure to mercury (amalgam) and nitrous oxide among female dentists.
