What is the gender distribution of those who perform potentially hazardous scientific experiments?
While I'm not aware of any research on employees exposed to safety risks in the academic workplace, there are statistics on actual workplace injuries in a variety of occupations, including scientific occupations.  If the incidence of injury is uniform across gender among those exposed to safety risks (I don't know if it is), then you can take this as a proxy for the gender distribution of those exposed to risk in the scientific workplace.

In particular, the United States Bureau of Labor Statistics collects information on workplace injuries, which you can query at will.

According to their statistics, here are the numbers of nonfatal occupational injuries involving days away from work among employees whose occupation is classified as "Life, Physical, and Social Science Occupations":



I was also interested in the ratio of the number of injuries to the number of thousands of people of each gender employed, again in "Life, Physical, and Social Science Occupations":



Please visit the BLS website to learn more about how they collect these statistics and what they mean.

You can query their dataset yourself if you're interested in getting numbers specific to one area of science or another.