A comparison of results from two test methods for assessing the toxicity of aminotriazole to Selenastrum capricornutum

Two different test methods for assessing the toxicity of aminotriazole to Selenastrum capricornutum are compared. Growth medium composition is demonstrated to have a significant effect on the toxicity of aminotriazole.     

Octachlorodibenzo-p-dioxin in wood treatment materials and treated wood

The octachlorodibenzo-p-dioxin (OCDD) concentrations have been determined in aged samples of commercial pentachlorophenol (PCP), in wood protection formulations containing PCP and in wood treated with PCP as a preservative or as an anti-sapstain treatment. The concentrations of OCDD found in the various samples are within the range expected from the amount of commercial PCP initially present in the samples. In view of the known stability of OCDD the results are interpreted as indicating that the formulation, treatment and ageing processes have not led to any substantial conversion of PCP to OCDD; although one result indicates that outdoor exposure of treated samples increased the OCDD concentration by a factor of approximately 2 after $\text{3}\text{1}\text{2}$ years. Analysis of aged samples of treated wood indicate that OCDD is lost much less rapidly from the wood than PCP.     

Uptake of gamma-HCH (Lindane) by pipistrelle bats and its effect on survival

Adult pipistrelle bats were caught at two roosts in Eastern England and kept in captivity on an ad lib diet of mealworms. In Experiment 1, two groups of eight bats were each kept in identical outdoor enclosures where the bats could fly freely and where they had a choice of five roost boxes, one of which was heated. One of these groups was exposed to gamma-HCH applied to planed pine blocks which had been immersed in a hexane solution of gamma-HCH. An initial concentration, estimated from surface wood scrapings, of 9.94 +/- 1.15 mg m(-2) was used for the first 44 days, while 866 +/- 51 mg g(-2) was used for a further 44 days. Blocks were placed in the roost boxes to simulate the type of exposure experienced by wild bats. Blocks dosed with solvent alone were given to the other group of bats (controls). Six of the eight bats in the group exposed to gamma-HCH died, while all bats in the control group survived (P < 0.007). In Experiment 2, three groups of five bats were kept in identical cages. Two groups were exposed to identical wood blocks dosed with gamma-HCH, which gave a concentration of 211 mg m(-2) in surface scrapings taken 1-2 h after dosing, while the other group received a wood block treated with solvent alone (control). All bats in the groups exposed to gamma-HCH died within 17 days, while all bats in the control group survived (P < 0.001). Tissues of bats were analysed for gamma-HCH by gas chromatography. There was a critical concentration of 622 +/- 102 microg gamma-HCH g(-1) extractable lipid at which bats died. The total weight of gamma-HCH in bat carcasses was directly related to the weight of extractable lipid. On average, bats died when the gamma-HCH concentration in the whole body reached 27.9 +/- 4.8 microg g(-1), but this value increased as body weight increased. This study confirmed the results of a previous study that gamma-HCH is toxic to bats in conditions simulating exposure in the wild.     

Analysis of polychlorobiphenyls from used transformers for polychlorodibenzofurans

The results of analyses for polychlorodibenzofuran (PCDF) content in two samples of polychlorobiphenyl (PCB) from used electrical transformers are presented and discussed. In neither sample was there evidence for enhanced PCDF concentrations even though one of them had been subjected to overheating while in service.     

Polychlorodibenzo-p-dioxins and dibenzofurans in technical pentachlorophenol - results of a collaborative analytical exercise

Results of analyses of eight samples of technical pentachlorophenol conducted by three different analytical methods are presented and discussed.     

An investigation of aqueous activity coefficients at low concentrations

The activity of a chemical in solution determines its tendency to move into other media. At low concentrations (<0.01M) it is generally considered to be linearly related to concentration. A hypothetical model based on the structure of liquid water is discussed which could cause deviations from this linearity in the ppb region, a concentration much lower than that normally investigated thermodynamically, but one of great importance environmentally. Headspace experiments are reported with carbon tetrachloride and chloroform in water at concentrations down to ～10^?3 ppb but no such deviations were discerned.     

Long term changes in polychlorodibenzo-p-dioxin concentrations in wood treated with technical pentachlorophenol

Wood samples treated with technical pentachlorophenol (PCP), technical sodium pentachlorophenoxide (NaPCP) and octachlorodibenzo-p-dioxin have been exposed outdoors for periods up to $\text{2}\text{1}\text{2}$ years. Analysis of extracts from the samples show that photolytic reductive dechlorination of highly chlorinated dibenzo-p-dioxins to less chlorinated isomers occurs. However there is no discernible increase in polychlorodibenzo-p-dioxin concentrations in the technical PCP treated wood presumably because further photolytic reactions and volatilisation compete effectively with the photolytic formation. There is no evidence for formation of octachlorodibenzo-p-dioxin (OCDD) in technical PCP treated wood in this study, probably because photolytic destruction and volatilisation compete effectively with formation reactions when the initial OCDD concentration is relatively high.