Comparison of the acute toxicity for gamma-cyhalothrin and lambda-cyhalothrin to zebra fish and shrimp

Gamma-cyhalothrin 15CS (GCH) contains only the active stereoisomer of the two isomers found in lambda-cyhalothrin 25EW (LCH). GCH (0.5 x rate) provides equivalent overall insect control as LCH (1 x rate). Both formulations showed high acute toxicity to zebra fish (Brachydanio rerio H.B.) and shrimp (Macrobrachium nippoensis de Haan). The 96-h LC(50(zebra fish,GCH)) is 1.93 microg a.i/L and LC(50(zebra fish,LCH)) is 1.94 microg a.i/L. LC(50(shrimp,GCH)) is 0.28 microg a.i./L and LC(50(shrimp,LCH)) 0.04 microg a.i./L. This indicates that the toxicity to shrimp is likely stereochemistry-dependent. The fates of GCH and LCH are similar in laboratory simulated rice paddy water and their concentrations decrease rapidly, with no GCH or LCH detected after 3 or 4 days. Both are toxic to shrimp in a simulated paddy irrigation reservoir even though treated return water is diluted 5 times. No shrimp fatality is shown in the GCH-treated paddy water after a 4-day holding period, and longer than 5 days is necessary to reach a zero fatality rate for LCH. This is compatible with the 7-day water holding period considered reasonable in agricultural practice.

Gridded usage inventories of technical hexachlorocyclohexane and lindane for China with 1/6 degrees latitude by 1/4 degrees longitude resolution

China banned the use of technical HCH (BHC: 1,2,3,4,5,6-hexachlorocyclohexane) in 1983; lindane has been used in this country since 1991. The total production was around 4 million t for technical HCH from 1952 to 1984, and 11,400 t for lindane between 1991 and 2000. Though the total produced technical HCH was considered to be used in China, only 3,200 t of lindane were used between 1991 and 2000 with the rest for export or on unused stack. Annual usage of these two compounds was located into each province first and then broken for different crops. Inventories of gridded usage of both technical HCH and lindane with 1/6 degrees by 1/4 degrees latitude/longitude resolution have been created by different gridded cropland data sets as surrogate data. The intensive use of technical HCH on croplands was concentrated in the southeastern part of China, but the use of lindane was concentrated in the northern part of China.

Histological classification of schistosomal egg induced polyps of colon and their clinical significance. An analysis of 272 cases

272 cases of schistosomal egg induced polyps collected from mass-screening for colorectal carcinoma in Jiashan County were divided into 3 types: fibrous type (FT), mixed type (MT) and epithelial proliferative type (ET). The ET was characterized by crypt elongation, hypertrophy, variation in size, disorderly arrangement, as well as the high percentage of atypical hyperplasia (64.9%). The coexistence and transition between inflammatory reactive hyperplastic and neoplastic crypts were noticed. By HID/AB staining, sialomucins were increased in ET, CEA and PNA receptors detected by the ABC method were present in 18/20 and 6/18 of ET respectively. The mucin expression of ET was similar to that of adenomas. It is likely that a spectrum of ET, atypical hyperplasia and adenoma may exist. We suggest that the patients with ET, especially those with atypical hyperplasia, should be regarded as "risk group", and close follow-up is needed.