Toxicities to many organs caused by humidifier disinfectants have been reported. Recently, humidifier disinfectants have been reported to cause cardiovascular, embryonic, and hepatic toxicities. This study was designed to investigate the toxic mechanism of humidifier disinfectants and compare toxicity in a cellular model and a zebrafish animal model. Because brain toxicity and skin toxicity have been less studied than other organs, we evaluated toxicity in a human dermal cell line and zebrafish under various concentrations of humidifier disinfectants that included polyhexamethyleneguanidine phosphate (PHMG), oligo-[2-(2-ethoxy)-ethoxyethylguanidinium- chloride] (PGH) and methylchloroisothiazolinone/methylisothiazolinone (CMIT/MIT). A human dermal fibroblast cell line was treated with disinfectants (0, 2, 4, 6, 8, and 16 mg L-1) to compare their cytotoxicity. The fewest PHMG-treated cells survived (up to 33%), while 49% and 40% of the PGH- and CMIT/MIT-treated cells, respectively, survived. The quantification of oxidized species in the media revealed that the PHMGtreated cells had the highest MDA content of around 28 nM, while the PGH- and CMIT/ MIT-treated cells had 13 and 21 nM MDA, respectively. As for brain toxicity, treatment of the zebrafish tank water with CMIT/MIT (final 40 mg L-1) for 30 min resulted in a 17- fold higher production of reactive oxygen species (ROS) than in the control. Treatment with PGH or PHMG (final 40 mg L-1) resulted in 15- and 11-fold higher production, respectively. The humidifier disinfectants (PHMG, PGH, and CMIT/MIT) showed severe dermal cell toxicity and brain toxicity. These toxicities may be relevant factors in understanding why some children have language disorders, motor delays, and developmental delays from exposure to humidifier disinfectants.

The aims of the present study were to estimate the possibility for toxicity test and compare acute toxicity of potassium dichromate in the larva stage of Neocaridina denticulata, Daphnia magna and the juvenile stage of Oryzias latipes. N. denticulate, a freshwater shrimp lives in Korea, is an indigenous species and considered to be useful for toxicity test. D. magna and O. latipes were recommended as a test species for the OECD test guideline. The 96 h-LC50 potassium dichromate value was 0.62 mg L-1 for the larva stage of N. denticulata and 168.44 mg L-1 for the juvenile stage of O. latipes. The 48 h-EC50 value was 1.27 mg L-1 for the D. magna. The study was confirmed higher sensitivity of the larva stage of N. denticulata to potassium dichromate compared to the D. magna and the juvenile stage of O. latipes.

The toxicity and toxin composition between blue mussel, Mytilus edulis and oyster, Crassostrea gigas collected at Woepori in Koˇ je island in South Coast of Korea in 1996 and 1997 were compared. The highest toxicity score was about 10 times higher in blue mussel than oyster (blue mussel, 8,670 ㎍; oyster, 860 ㎍ in 1996, blue mussel, 5,657 ㎍; oyster, 531 ㎍/100 g in 1997). The blue mussel also retained its toxicity for slightly longer period than oyster. In the both shellfish, PSP was composed almost exclusively of C toxins (C 1 and C2, 2065%) and gonyautoxins (GTX1, 2, 3 and 4, 38-78%). In the early period of toxin accumulation, the ratio of 11(3-epimer toxins (C2, GTX4) whose amount was 2556 mole% (5th March to 12th April in 1996) and 2580 mole% (18th March to 7th April in 1997), were higher than that of llα-epimer toxins (C1, GTX2) in both shellfish. As the lapse of intoxification time, however, the ratio of 11-epimer toxins (C1, GTX2) whose amount was 41-57 mole% (27th May to 3rd June in 1996) and 25-56 mole% (29th April to 12th May in 1997), became higher than that of 11-epimer toxins. The toxin compositions in the both samples changed on a daily basis, presumably owing to metabolism of the toxins in the bivalves.