Triclosan (TCS) and trichlocarban (TCC) are used as antimicrobials in soaps and other household products, because of their antibacterial and anti-fungal properties. We assessed the potential toxicological effects associated with TCS and TCC using Caenorhabditis elegans (C. elegans) as a model soil organism. We examined changes in the test endpoints of growth and maturation such as body length,ratio (%) of gravid worms and fecundity. Growth tests showed that the lowest observed effective concentrations (LOEC) of TCS and TCC in C. elegans were 0.78 and <0.074 mg/L, respectively. The estimated LOEC values in maturation tests were 3.13 mg/L for TCS and 0.17 mg/L for TCC. The estimated LOEC for TCC in reproduction tests was 0.11 mg/L, but this could not be determined for TCS (>6.25 mg/L). We also investigated the suitability of the DNA microarray as an eco-toxicogenomic approach to determine the physiological function of TCS and TCC in C. elegans. Both TCS (5.0 mg/L) and TCC (0.166 mg/L) were examined mainly as cytochrome P450 (CYP) gene expression using a customized chip for C. elegans. Among 79 CYP genes, 19 and 10 were up-regulated upon exposure to TCS and TCC, respectively. Both TCS (5.0 mg/L) and TCC (0.166 mg/L) were common to indicate the induction ability of CYP35As, which function is related to mammalian CYP2 clade.
A case study to analyze the behavior of an experimenter and the treatment of chemical substances within a laboratory was carried out in an actual academic chemical laboratory using fixed-point observation via web cameras. The behavior of an experimenter, an undergraduate student in a polymer chemistry research group, was monitored by ten web cameras. The experimenter's behavior in the laboratory was classified into three groups: operations in the protocol, complementary operations not explicitly in the protocol, and movements around the laboratory. The total time spent on these complementary operations was found to equal or exceed that spent on the work actually operations in the protocol, suggesting that risk assessments of laboratory experiments need to account for complementary procedures beyond those operations in the protocol. The findings also suggest that changes and adjustments to the experimental scenario must be taken into account in risk assessment. An analysis of the time distribution of the experimenter's work showed that, though he used many places in the laboratory in line with his experimental protocol, the laboratory bench acted as the hub of his experimental activity. In contrast, chemicals were used in very few locations within the laboratory, and relatively little time was spent using chemicals at the laboratory bench. Results suggested that glassware cleaning is the work that gives rise to by far the most risk of chemical exposure compared to other experimental operations. These findings are expected to contribute to a more informed discussion of risk assessment with regard to laboratory experiments.
Student safety is an important issue and many measures have been taken to protect students.However the safety of international graduate students working in research laboratories in Japan has not received much attention. This is a report of the steps taken at Ehime University to promote safety in the laboratory with suggestions for future action.