PubMed · 544563
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F T Cross. 1979. Exposure standards for uranium mining.. https://doi.org/10.1097/00004032-197912000-00006
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Chloroform (CHCl3) is a short-lived ozone-depleting substance not currently regulated under the Montreal Protocol. Due to the unique meteorological conditions in East Asia, CHCl3 emitted in this region has a greater potential to reach the stratosphere and contribute to ozone depletion. As an essential component of national CHCl3 emissions, southeastern China has attracted increasing attention. However, long-term observational data in this region remain relatively scarce, with no updates since 2020. In this study, we continuously measured atmospheric CHCl3 concentrations at a remote monitoring station in southeastern China from 1 June 2023 to 31 May 2025. Frequent concentration enhancements were observed during the monitoring period, with mixing ratios ranging from 9.3 to 134.1 ppt and an average value of 36.8 ± 19.7 ppt. Back-trajectory analysis indicated that air masses associated with elevated CHCl3 levels primarily originated from coastal industrial provinces in eastern China. Using the Potential Source Contribution Function and Concentration Weighted Trajectory methods, we identified the Yangtze River Delta (Jiangsu, Anhui, and Zhejiang Provinces) and Jiangxi Province as dominant source regions. Emissions of CHCl3 in southeastern China were estimated using the Tracer Ratio Method to be approximately 30.1 ± 5.3 Gg/yr from 2023-06-01 to 2025-05-31, indicating overall stability relative to earlier estimates and no apparent upward trend. These findings provide updated insights into the current status of CHCl3 emissions in southeastern China and highlight the need for continued monitoring and emission assessment of CHCl3 in East Asia, given its unregulated status and implications for ozone layer recovery.
Diesel exhaust is known to induce tumors in animals and is suspected of being carcinogenic in humans. Of the compounds found in diesel exhaust and in airborne particulate matter, 3-nitrobenzanthrone (3-NBA), is a particularly powerful mutagen. We investigated the capacity of 3-NBA to form DNA adducts in vivo that could be used as agent-specific biomarkers of exposure. Female Sprague-Dawley rats were treated orally with 2 mg/kg body weight of 3-NBA, and DNA from various organs was analyzed by (32)P-postlabeling. High levels of 3-NBA-specific adducts were detectable in all organs. Both enrichment versions nuclease P1 digestion and n-butanol extraction resulted in patterns consisting of either 3 or 4 adducts remarkably similar in all tissues examined. The highest level of DNA adducts was found in the small intestine (38 adducts per 10(8) nucleotides) followed by forestomach, glandular stomach, kidney, liver, lung and bladder. To provide information on the nature of the adducts formed in vivo in rats, DNA adducts were cochromatographed in 2 independent systems with standardized deoxyguanosine adducts and deoxyadenosine adducts produced by reaction of 3-NBA in the presence of xanthine oxidase with deoxyribonucleoside 3'-monophosphates in vitro. In both systems, each of the rat adducts comigrated either with a deoxyguanosine or a deoxyadenosine-derived 3-NBA adduct. Our results demonstrate that 3-NBA binds covalently to DNA after metabolic activation, forming multiple DNA adducts in vivo, all of which are products derived from reductive metabolites bound to the purine bases (deoxyguanosine 60% and deoxyadenosine 40%).
Refuse incineration data for New York City (NYC) have been compiled as a function of time during the 20th century to assess the historical significance of this pollutant source in a densely populated area. Thirty-two municipal and 17,000 apartment house refuse incinerators were identified. Approximately 1.1 x 10(8) t of refuse (wet weight) were combusted in NYC incinerators between 1908 and 1993, producing 3.4 x 10(7) t(dryweight) of combustion residue disposed in local landfills. Refuse incinerators were operated for most of this period without air pollution control and emitted 1.0 x 10(6) t of particles (a total of 120 mg for each cm2 of land in NYC). Incinerator particle emission (PE) rates per unit area of land were highest in Manhattan (equivalent total deposition of 530 mg cm(-2)). Incinerator PE exceeded 1.2 x 10(4) t yr(-1) between 1930 and 1975, with maximum emission rates (>2.2 x 10(4) t yr(-1)) in the late 1930s and 1960s. These and other factors support the conclusion that refuse incineration without air pollution control was an important source of airborne, respirable pollutants in NYC for many decades during the 20th century. Rates of particle emissions from Manhattan incinerators estimated here correlate stronglywith Pb accumulation rates as a function of depth (time) in Central Park Lake sediments, consistent with refuse incineration emitting large amounts of atmospheric lead in NYC for many decades afterthe 1920s.