Sheehan P, Ricks R, Ripple S, Paustenbach D
ChemRisk, A Division of McLaren/Hart, Alameda, CA 94501.
Am Ind Hyg Assoc J. 1992 Jan;53(1):57-68. doi: 10.1080/15298669291359302.
Hexavalent chromium, Cr(VI), has been classified as a human respiratory carcinogen. Airborne Cr(VI) emissions are associated with a number of industrial sources including metal plating, tanning, chromite ore processing, and spray painting operations; combustion sources such as automobiles and incinerators; and fugitive dusts from contaminated soil. There has been considerable interest within industry and the regulatory community to assess the potential cancer risks of workers exposed to Cr(VI) at levels substantially below the threshold limit value (TLV) of 50 micrograms/m3. To date, only the workplace sampling and analytical method (National Institute for Occupational Safety and Health [NIOSH] Method 7600) has been validated for measuring airborne Cr(VI), and it can accurately measure concentrations only as low as 500 ng/m3. This paper describes the field evaluation of a sampling and analytical method for the quantitation of airborne Cr(VI) at concentrations 5000 times lower than the current standard method (as low as 0.1 ng/m3). The collection method uses three 500-mL Greenberg-Smith impingers in series, operated at 15 Lpm for 24 hr. All three impingers are filled with 200 mL of a slightly alkaline (pH approximately 8) sodium bicarbonate buffer solution. The results of validation tests showed that both Cr(VI) and trivalent chromium, Cr(III), were stable in the collection medium and that samples may be stored for up to 100 days without appreciable loss of Cr(VI). Method precision based on the pooled coefficient of variation for replicate samples was 10.4%, and method accuracy based on the mean percent recovery of spiked samples was 94%. Both the precision and accuracy of the impinger method were within NIOSH criteria. This method could be used to measure ambient concentrations of Cr(VI) in the workplace caused by fugitive emissions from manufacturing processes or chromium-contaminated soils at workplace concentrations well below the current TLV (50 micrograms/m3) or permissible exposure limit (100 micrograms/m3).
六价铬（Cr(VI)）已被列为人类呼吸道致癌物。空气中的Cr(VI)排放与多种工业来源有关，包括金属电镀、制革、铬铁矿加工和喷漆作业；汽车和焚烧炉等燃烧源；以及受污染土壤产生的扬尘。工业界和监管机构对评估接触Cr(VI)水平远低于50微克/立方米阈限值（TLV）的工人的潜在癌症风险一直相当关注。迄今为止，只有工作场所采样和分析方法（美国国家职业安全与健康研究所[NIOSH]方法7600）已被验证可用于测量空气中的Cr(VI)，且它只能准确测量低至500纳克/立方米的浓度。本文描述了一种采样和分析方法的现场评估，该方法用于定量浓度比当前标准方法低5000倍（低至0.1纳克/立方米）的空气中的Cr(VI)。采集方法使用三个串联的500毫升格林伯格 - 史密斯冲击式吸收管，以15升/分钟的流量运行24小时。所有三个冲击式吸收管都装有200毫升微碱性（pH约为8）的碳酸氢钠缓冲溶液。验证测试结果表明，Cr(VI)和三价铬（Cr(III)）在采集介质中均稳定，并且样品可储存长达100天而Cr(VI)无明显损失。基于重复样品合并变异系数的方法精密度为10.4%，基于加标样品平均回收率的方法准确度为94%。冲击式吸收管方法的精密度和准确度均符合NIOSH标准。该方法可用于测量工作场所中由制造过程的无组织排放或铬污染土壤导致的Cr(VI)环境浓度，其工作场所浓度远低于当前的TLV（50微克/立方米）或允许接触限值（100微克/立方米）。
