Antarctic-wide array of high-resolution ice core records reveals pervasive lead pollution began in 1889 and persists today.

Interior Antarctica is among the most remote places on Earth and was thought to be beyond the reach of human impacts when Amundsen and Scott raced to the South Pole in 1911. Here we show detailed measurements from an extensive array of 16 ice cores quantifying substantial toxic heavy metal lead pollution at South Pole and throughout Antarctica by 1889 - beating polar explorers by more than 22 years. Unlike the Arctic where lead pollution peaked in the 1970s, lead pollution in Antarctica was as high in the early 20(th) century as at any time since industrialization. The similar timing and magnitude of changes in lead deposition across Antarctica, as well as the characteristic isotopic signature of Broken Hill lead found throughout the continent, suggest that this single emission source in southern Australia was responsible for the introduction of lead pollution into Antarctica at the end of the 19(th) century and remains a significant source today. An estimated 660 t of industrial lead have been deposited over Antarctica during the past 130 years as a result of mid-latitude industrial emissions, with regional-to-global scale circulation likely modulating aerosol concentrations. Despite abatement efforts, significant lead pollution in Antarctica persists into the 21(st) century.

Comparison of contraceptive choices of rural and urban US adults aged 18-55 years: an analysis of 2004 behavioral risk factor surveillance survey data.

INTRODUCTION: Although sexually active US adults wanting to prevent pregnancy have a wide variety of birth control methods readily available, there is little research that documents the contraceptive choices of rural adults in comparison to urban adults. This study compared the contraceptive choices of rural with urban adults. The comparative analysis joins the recent dialog in population health focused on assessing health related differences to detect if these are indicative of rural health disparities. DESIGN: This was a cross-sectional study analyzing 2004 Behavioral Risk Factor Surveillance Survey (BRFSS) data. Place of residence was ascertained by re-coding the state/county FIPS code as either urban or rural, based on 2003 Rural-Urban Continuum Codes from the US Office of Management and Budget (setting: US households; participants: US adults 18-55 years). MAIN OUTCOME MEASURES: characteristics and contraceptive method choice of rural adults using birth control. RESULTS: A multivariate regression model performed with 'use of birth control' as the dependent variable yielded that rural in comparison with urban adults 18-55 years were more likely to use female or male sterilization, non-injectable and injectable hormones for birth control. They were less likely to use: condoms, a diaphragm or NuvaRing, emergency contraception, withdrawal or rhythm methods. Additionally, in comparison with urban adults, rural persons younger than 35 years, those who had children younger than 18 years living with them, those who were partnered, males and those living in households with an income of less than US$35,000 were more likely to report using some form of contraception. CONCLUSION: There were differences in the contraception choices of urban and rural adults. How much primary care provider preferences explains the differences is not known and bears further exploration. These results should prove useful to healthcare providers as well as public health family planning programs.

Transport of acridine in saturated porous media.

The effects of the aqueous solution pH, temperature, initial solute concentration and non-equilibrium processes on the transport of acridine in saturated porous media (silica) were investigated in a series of continuous-flow column experiments. The enthalpy of the adsorption reaction was more exothermic when the solution pH was above acridine's pKa (5.6) than when it was below. The extent of adsorption was greater when the solution pH was below the pKa of acridine than when it was above. Non-equilibrium effects on the adsorption reaction were found to be unimportant at groundwater velocities. The results from this study suggest that the mobility of acridine in aquifers, in which adsorption to silica edge sites is significant, would increase as the temperature of the groundwater increased and the acridine mobility would be greatest when the pH of the groundwater is above the pKa of acridine. The transport of acridine in such aquifers can be effectively modeled using the local equilibrium assumption.

Mortality among industrial workers exposed to formaldehyde.

A historical cohort study evaluated the mortality experience of 26,561 workers employed in 10 formaldehyde-producing or -using facilities. Approximately 600,000 person-years of follow-up accrued as workers were followed to January 1, 1980. Estimates of historical exposure to formaldehyde by job were developed by project industrial hygienists using monitoring data available from participating plants, comments from long-term workers, and comprehensive monitoring data specifically collected for this study. Mortality from all causes combined was about as expected [standardized mortality ratio (SMR) = 96] based on mortality rates of the general U.S. population. Significantly fewer deaths occurred from infective and parasitic diseases (SMR = 51) and from accidents (SMR = 72) than expected. Cancer overall was not related to formaldehyde exposure. Workers exposed to formaldehyde had slight excesses for Hodgkin's disease and cancers of the lung and prostate gland, but these excesses were not consistently related to duration of or average, cumulative, or peak formaldehyde exposure levels. Recent animal studies found nasal cancer among rats exposed to formaldehyde, but no excess of this tumor occurred in this study. Mortality from brain cancer and leukemia among these industrial workers was not excessive in contrast to reported excesses among professional groups (e.g., anatomists, embalmers, and pathologists) with exposure to formaldehyde. Although there was a deficit for cancer of the buccal cavity and pharynx, mortality from certain subsites, i.e., the nasopharynx and oropharynx, was elevated. These subsites did not, however, show a consistently rising risk with level of exposure. These data provide little evidence that mortality from cancer is associated with formaldehyde exposure at levels experienced by workers in this study.

Warfarin: stereochemical aspects of its metabolism in vivo in the rat.

The biotransformation of the R and S isomers of warfarin was investigated in the rat. The formation of 7-hydroxywarfarin was stereoselective for the R enantiomer, while the formation of 4'-hydroxywarfarin was stereoselective for the S enantiomer. The 6-, 8-, and benzylic hydroxylation of both isomers was approximately the same. The reduction of the side chain ketone function of warfarin to the corresponding diastereomeric warfarin alcohols was stereoselective for the S isomer. The reduction also displayed a degree of stereospecificity with S reduction occurring predominantly. The results of the in vivo study agree in many cases with a previous in vitro investigation. However, differences between the in vitro and in vivo studies do exist and suggest that secondary stereoselective biotransformation routes occur in vivo and that the microsomal and soluble enzymes employed in the in vitro study may have been disrupted during isolation. Large amounts of polar labile conjugates of R and S warfarin, and metabolites were found in the urine. The 4-hydroxyl group of the coumarin ring appears to be the position of conjugation and this process appears to be regio and stereoselective.