Three decades (1983-2010) of contaminant trends in East Greenland polar bears (Ursus maritimus). Part 1: legacy organochlorine contaminants.

Legacy organochlorine contaminants were determined in adipose tissues from 294 polar bears (Ursus maritimus) sampled in East Greenland in 23 of the 28years between 1983 and 2010. Of 19 major legacy contaminants and congeners (ΣPCB, 4 PCB congeners (CB153, 180, 170/190), ΣDDT, p,p'-DDE, p,p' -DDD and p,p'-DDT, α- and ß-hexachlorocyclohexane (HCH), HCB, octachlorostyrene, dieldrin, oxychlordane, cis- and trans-chlordane, cis- and trans-nonachlor, heptachlor epoxide and BB-153), 18 showed statistically significant average yearly declines of -4.4% (range: -2.0 to -10.8%/year) among subadult polar bears (i.e. females<5years, males<6years). For example, the ∑PCB concentrations declined 2.7 fold from 22730ng/g lw (95% C.I.: 12470-32990ng/g lw) in 1983-1986 to 8473ng/g lw (95% C.I.: 6369-9776ng/g lw) in 2006-2010. Similar but fewer statistically significant trends were found for adult females and adult males likely due to smaller sample size and years. Despite declines as a result of international regulations, relatively high levels of these historic pollutants persist in East Greenland polar bear tissues.

Modelling historical budget of alpha-hexachlorocyclohexane in Taihu Lake, China.

Historical alpha-hexachlorocyclohexane (alpha-HCH) budget in Taihu Lake (TL), China has been simulated by a Gridded Basin-based Pesticide Mass Balance Model (GB-PMBM). Using annual usage of alpha-HCH from 1952 to 1984 as input, the model outputs included annual concentrations in air, water and sediment in TL, and annual cumulative burden of alpha-HCH in the lake water and sediment from 1952 to 2008. Model results showed that the modeled alpha-HCH in the air, water and sediment matched their corresponding measured data well, and the current levels of alpha-HCH in the air, water and sediment in TL in 2008 are 11.7 (3.4-22.7) pgm(-3), 0.8 (0.3-1.5) ng L(-1) and 0.18 (0.04-0.46) ng g(-1)dw (dry weight), respectively. The alpha-HCH burden in TL water started to accumulate after 1952, reached the highest value of 11,000kg in 1972, decreased very quickly since the beginning of 1980s, reduced to 200 kg in 1984 and 3 kg in 2008. It was found that TL water played a role of "distributor" in process of transport of alpha-HCH. Before 1980, TL water took a large amount of alpha-HCH from atmosphere through a huge air-water interface and carried a major portion of it out of the lake through water current. After 1980, TL water took alpha-HCH from lake sediments and river water entering the lake, and released almost all of it to air. The lake water itself cannot hold a large portion of the chemical due to its shallow depth and short residence time.

Evaluating the fate of three HCHs in the typically agricultural environment of Liaoning Province, China.

The LRBPOP model has been developed to calculate the long-term fate of alpha-, beta-, and gamma-hexachlorocyclohexane (HCH) in the lower reach of Liaohe River basin, a typically agricultural environment in Liaoning Province, China. For this purpose, seasonally existent crop compartment, time-variant emission rates, and seasonal model parameters are provided in the model calculation. Besides, crop processing factor (PF) is also introduced to calculate the concentration in foodstuff produced by crop. The fate of three HCHs from 1952 to 2011 is calculated. Sensitivity analysis, uncertainty analysis, and model comparison are conducted to evaluate the model. The sensitivity analysis indicates that the LRBPOP model is most sensitive to air and water advection, HCHs applied rate, and reaction half-life in soil. Model comparison shows that absolute levels, partitioning between media, temporal trends, and ratios between HCHs reproduce well within an order of magnitude, often within a factor of 3. The predicted results indicate that the study area has been subject to severe contamination of HCHs in the early of 1980s, and the residues of three HCHs decrease largely with different vanishing rates after 1983. According to modeling results, the 97.5th percentiles of SigmaHCH residues in surface water, agricultural soil, and crop food are lower than the corresponding maximum residue limits (MRLs) in 2008, 2005, and 2005, respectively.

Reflexões sobre alguns ensaios com o Gammexane no combate aos transmissores da doença de Chagas, de Emmanuel Dias e José Pellegrino, 1948: conquistas e desafios no contexto da diversidade triatomínica, cem anos após a descoberta da tripanossomíase americana / Reflections on some tests with the Gammexane transmitters in the fight against Chagas disease, Emmanuel Dias and Joseph Pellegrino, 1948: achievements and challenges in the context of triatomine diversity, one hundred years after the discovery of American trypanosomiasis

Revisões históricas aos avanços científicos para o controle da doença, o Simpósio Internacional Comemorativo do Centenário da Descoberta da Doença de Chagas (1909-2009).

Hexachlorocyclohexane use in the former Soviet Union.

Because of the large size of the former Soviet Union (FSU) and the heavy use of organochlorine pesticides (OCPs) in the FSU, usage information regarding OCPs in the FSU is important in compiling global emission inventories and thus in studying the transport of OCPs among different environmental compartments worldwide. The availability of such information is limited. By analyzing the available 1,2,3,4,5,6-hexachlorocyclohexane (HCH) data in the FSU, this article presents estimates of HCH usage in this region from 1950 to 1990, when HCH was officially banned for agricultural use by the FSU government. The creation of HCH usage inventories for the FSU has paved the way to produce HCH emission inventories for this region. Total HCH usages for agricultural purposes in the FSU from 1950 to 1990 were estimated to be 1,960 kt for technical HCH and 40 kt for lindane. The total usage for the isomers was 270 kt for gamma-HCH, 1,270 kt for alpha-HCH, and 170 kt for beta-HCH. Use of HCH reached a peak in 1965: 130 kt for technical HCH, 2.7 kt for lindane, 18 kt for gamma-HCH, 86 kt for alpha-HCH, and 11 kt for beta-HCH. Gridded usage data sets in the FSU of technical HCH and lindane-and the alpha-HCH, beta-HCH and gamma-HCH isomers-on a 1degree x 1degree longitude and latitude grid system for 1980 are freely available to all users at http://www.msc.ec.gc.ca/data/gloperd/.

Marine organic pollution history in the Changjiang Estuary and Zhejiang coastal area--HCHs and DDTs stratigraphical records.

The variations of concentrations of hexachloro-cyclohexane (HCHs), dichloro diphenyl trichloroethane (DDTs) in surface sediments from the Changjiang Estuary and Zhejiang coastal area suggests that although there is a substantial decrease of these persistent trace compounds since the last two decades, they still presented in recent surface sediments. Their concentration levels in suspended matter are still quite high. In dated sedimentary cores, the DDTs and HCHs concentration peaks appeared in 1960s to 1980s, which approximately corresponded to their production and usage history.

Gas-phase polychlorinated biphenyl and hexachlorocyclohexane concentrations near the Great Lakes: a historical perspective.

The Integrated Atmospheric Deposition Network (IADN) has been measuring gas-phase, polychlorinated biphenyl (PCB) concentrations at sites near Lakes Michigan and Superior for over a decade. Data through 2000 were used in this study to investigate PCB temporal trends in the Great Lakes atmosphere. Decreasing trends were found at both sites, and half-lives of approximately 20 yr were calculated using IADN data. However, when these data were supplemented by historical data for Lakes Michigan and Superior dating back to 1977, half-lives dropped to 10 and 6 yr, respectively. These latter half-lives agreed well with half-lives in other environmental compartments. Exponential curves fitted to the historical and IADN data indicated little decline in PCB concentrations in the basin since the mid-1990s. A similar historical analysis of alpha-and gamma-hexachlorocyclohexane (HCH) data indicated that IADN data were the best predictor of trends, resulting in half-lives of around 4 yr for both compounds. Gamma-HCH concentrations, however, have shown little decline in recent years, most likely because of its continuing use. PCB and alpha-HCH temporal trends indicated that bans on these substances have helped to remove them from the atmosphere. This work also showed that decades of data may be necessary to properly interpret long-term temporal trends in gas-phase organochlorine concentrations.