Toxaphene trends in the Great Lakes fish

As part of the U.S. Great Lakes Fish Monitoring and Surveillance Program (GLFMSP), more than 300 lake trout (Salvelinus namaycush) and walleye (Stizostedion vitreum vitreum) collected from the Laurentian Great Lakes each year from 2004 to 2009, have been analyzed for total toxaphene and eight selected congeners. The analytical results show fish toxaphene concentrations are quite different among lakes. Between 2004 and 2009, Lake Superior lake trout had the highest concentration (119 to 482 ng/g) and Lake Erie walleye had the lowest concentration (18 to 47 ng/g). Combining these results with the historical total toxaphene data (1977–2003), temporal changes were examined for each lake. Because of different analytical methods used in the previous studies, the historical data were adjusted using a factor of 0.56 based on a previous inter-method comparison in our laboratory. Trend analysis using an exponential decay regression showed that toxaphene in Great Lakes fish exhibited a significant decrease in all of the lakes with t_1/2 (confidence interval) of 0.9 (0.8–1.1) years for Lake Erie walleye, 3.8 (3.5–4.1) years for Lake Huron lake trout, 5.6 (5.1–6.1) years for Lake Michigan lake trout, 7.5 (6.7–8.4) years for Lake Ontario lake trout and 10.1 (8.2–13.2) years for Lake Superior lake trout. Parlars 26, 50 and 62 were the dominant toxaphene congeners accounting for 0.53% to 41.7% of the total toxaphene concentration. Concentrations of these congeners generally also decreased over time.     

Atmospheric Concentrations of Toxaphene on the Coast of Lake Superior

Thirty-seven air samples were collected from September 1996 through December 1997 at Eagle Harbor, Michigan to determine the atmospheric concentration of toxaphene near Lake Superior. The concentrations ranged between 0 and 63 pg/m³, with most less than 20 pg/m³, which agreed well with concurrent measurements over the lake and near Lake Michigan made by other research groups. These concentrations are significantly lower than those measured in 1988 and 1989 in Egbert, a small city in southern Ontario. The phase transition energy was calculated to be 47 kJ/mol, half the value calculated for the Egbert site; this disparity has been seen in comparisons of lakeshore and over-land values for other compounds. If temperature effects are removed, the average toxaphene concentration for the Eagle Harbor samples was 6.4 ± 2.2 pg/m³, which was lower than the 16 pg/m³ average at Egbert, Ontario. This difference in concentration may (or may not) be due to differences in sampling dates or locations or in measurement techniques.     

Significance of toxaphene in Great Lakes fish consumption advisories

Fish consumption advisories have been issued for the Great Lakes generally based on the most restrictive contaminant. For the Canadian waters of the Great Lakes, toxaphene causes minor restrictions only in Lake Superior, i.e., 3% of the total (restrictive + unrestrictive) advisories issued. However, the significance of the hazard posed by toxaphene in fish is not clear since more restrictive advisories due to other priority contaminants may be masking the less restrictive advisories. We simulated fish consumption advisories for the Toxaphene-only scenario by neglecting the presence of contaminants other than toxaphene, and compared with the issued advisories as well as with the published simulated Mercury-only scenario. Restrictive advisories under the Toxaphene-only scenario compared to the issued toxaphene related advisories would increase from 3% to 14%, < 1% to 4%, and 0% to 2% for Lakes Superior, Huron and Ontario, respectively, and remain at 0% for Lake Erie. For Lake Superior, most of the restrictive Toxaphene-only advisories would be for fatty fish. Overall, the Toxaphene-only advisories would be significantly less restrictive compared to the issued advisories, and also generally less restrictive compared to the Mercury-only scenario. These results suggest that toxaphene is less of a concern than PCBs (including dioxin-like PCBs), dioxins–furans and mercury from the perspective of health risk to humans consuming Great Lakes fish; elevated toxaphene is mainly a concern for human consumers of Lake Superior fatty fish. Our results suggest that the routine monitoring of toxaphene in other Canadian waters of the Great Lakes and Lake Superior lean/pan fish could be discontinued.     

气相色谱-质谱法应用于动物源性食品中毒杀芬残留测定

本文对动物源性食品中毒杀芬残留分析进行了研究,对样品前处理条件进行优化,建立了乙腈匀浆超声提取,弗罗里硅土净化的前处理方法,采用气相色谱-质谱法（GC-MS）选择离子检测毒杀芬。实验结果表明毒杀芬在0.05mg/kg-0.5mg/kg范围内成线性关系,检出限为0.05mg/kg,回收率在60%~120%之间。该方法操作简便、快速,可作为动物源性食品中毒杀芬残留检测的定性及定量方法。     

Modeling toxaphene behavior in the Great Lakes

Chlorinated camphenes, toxaphene, are persistent organic pollutants of concern in the Great Lakes since elevated concentrations are found in various media throughout the system. While concentrations have decreased since their peak values in the 1970s and 80s, recent measurements have shown that the rate of this decline in Lake Superior has decreased significantly. This modeling study focused on toxaphene cycling in the Great Lakes and was performed primarily to determine if elevated water and fish concentrations in Lake Superior can be explained by physical differences among the lakes. Specifically, the coastal zone model for persistent organic pollutants (CoZMo-POP), a fugacity-based multimedia fate model, was used to calculate toxaphene concentrations in the atmosphere, water, soil, sediment, and biota. The performance of the model was evaluated by comparing calculated and reported concentrations in these compartments. In general, simulated and observed concentrations agree within one order of magnitude. Both model results and observed values indicate that toxaphene concentrations have declined in water and biota since the 1980s primarily as the result of decreased atmospheric deposition rates. Overall the model results suggest that the CoZMo-POP2 model does a reasonable job in simulating toxaphene variations in the Great Lakes basin. The results suggest that the recent findings of higher toxaphene concentrations in Lake Superior can be explained by differences in the physical properties of the lake (primarily large volume, large residence time and cold temperatures) compared to the lower lakes and increased recent inputs are not needed to explain the measured values.     

Brain Acetylcholinesterase and Backbone Collagen in Fish Intoxicated with Organophosphate Pesticides

The rationale for the use of brain acetylcholinesterase inhibition in fish exposed to organophosphate pesticides is presented. Cyprinid fish from pond cultures and native perch from the Rybinsk Reservoir of the Upper Volga Cascade were used in this joint effort. The results of exposure to the pesticides Dylox and malathion are described. Backbone collagen and hydroxyproline content studies, demonstrated as sensitive indicators to the pesticide toxaphene, were applied to the Dylox-exposed fish. Unlike toxaphene, Dylox exposure did not involve hydroxyproline. Rather, diminution of collagen formation is probably a function of inhibition of esterases. The effects of chronic exposure are also discussed. It was found that mortality may occur at a total dose, which is significantly less than the minimum lethal concentration.