Exposure assessment of laboratory students

The Massachusetts Institute of Technology (MIT) has two kinds of laboratories, teaching for undergraduate students and research laboratories for graduate students and research staff. The objective of this study is to determine chemical exposures during teaching and research activities. There are three hypotheses in this study: (1) Exposures in academic laboratories are well below health standards; (2) Students in undergraduate teaching laboratories have less chemical exposure compared to students in graduate research laboratories; and (3) Students in different disciplines are expected to have different exposures. From September 1996 to December 1996, 132 air samples were collected from both teaching and research laboratories in the departments of Material Sciences and Engineering, Chemical Engineering, and Biology. The most frequently sampled chemicals in these three departments were cobalt, styrene, and formaldehyde, respectively. A total of 23 different agents were measured. In this study, the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV)-short-term exposure limit (STEL) is used as the health-effect standard for exposure time less than four hours. The ACGIH TLV-TWA (time-weighted average) is used as the standard for exposure times equal to or greater than four hours. The ratio of measured concentrations to the appropriate ACGIH standard was then calculated. The geometric mean of the ratio for the total samples was 0.34 percent of the standards. There were 70 samples from teaching laboratories (geometric mean = 0.38% of the standards), and 62 samples from research laboratories (geometric mean = 0.08% of the standards). The chemical exposures relative to the standards in teaching laboratories were statistically higher than in research laboratories (p-value < 0.001). Information about personal protective equipment and the use of laboratory chemical hoods was also collected. The differences in use of personal protective equipment (PPE) among these departments was not statistically significant. From the air sampling results, we concluded that (1) Chemical exposures in the academic laboratories in this study were all well below the health standards; (2) Undergraduate students in teaching laboratories had higher chemical exposures than graduate students in research laboratories; (3) Chemical exposures among departments were not significantly different; and (4) Hazard communication, safety training, and laboratory rules enforcement are important for protection and may be the reason that the results from this study indicate that chemical exposures in this academic institution are well below the health standards under normal operations.