Suchergebnisse

Sanding joint compounds is a dusty activity and exposures are not well characterized. Until the mid 1970s, asbestos‐containing joint compounds were used by some people such that sanding could emit dust and asbestos fibers. We estimated the distribution of 8‐h TWA concentrations and cumulative exposures to respirable dusts and chrysotile asbestos fibers for four worker groups: (1) drywall specialists, (2) generalists, (3) tradespersons who are bystanders to drywall finishing, and (4) do‐it‐yourselfers (DIYers). Data collected through a survey of experienced contractors, direct field observations, and literature were used to develop prototypical exposure scenarios for each worker group. To these exposure scenarios, we applied a previously developed semi‐empirical mathematical model that predicts area as well as personal breathing zone respirable dust concentrations. An empirical factor was used to estimate chrysotile fiber concentrations from respirable dust concentrations. On a task basis, we found mean 8‐h TWA concentrations of respirable dust and chrysotile fibers are numerically highest for specialists, followed by generalists, DIYers, and bystander tradespersons; these concentrations are estimated to be in excess of the respective current but not historical Threshold Limit Values. Due to differences in frequency of activities, annual cumulative exposures are highest for specialists, followed by generalists, bystander tradespersons, and DIYers. Cumulative exposure estimates for chrysotile fibers from drywall finishing are expected to result in few, if any, mesothelioma or excess lung cancer deaths according to recently published risk assessments. Given the dustiness of drywall finishing, we recommend diligence in the use of readily available source controls.

AbstractThe potential for cancer‐related risks to community members from ambient exposure to elongate mineral particles (EMPs) in taconite processing has not been formally evaluated. We evaluated 926 ambient air samples including 12,928 EMPs (particle structures with length‐to‐width ratio ≥3:1) collected over 26 years near a taconite processing facility in Silver Bay, Minnesota. Eighty‐two percent of EMPs were ≤3 μm in length and 97% of EMPs had an average aspect ratio <20:1. A total of 935 (7.3%) EMPs had length >5 μm and AR ≥3:1. Average ambient concentration of NIOSH countable amphibole EMPs over all years was 0.000387 EMPs per cubic centimeter (EMP/cm3). Of 12,765 nonchrysotile EMPs, the number of amphiboles with length and width dimensions that correlate best with asbestos‐related carcinogenicity ranged from four (0.03%) to 13 (0.1%) and the associated ambient amphibole air concentrations ranged from 0.000003 to 0.000007 EMP/cm3. After 65 years of taconite processing in Silver Bay, evidence of an increased risk of mesothelioma and lung cancer in community members who did not work in the taconite industry is lacking. The absence of an increased risk of asbestos‐related cancer in the Silver Bay community is coherent with supporting evidence from epidemiological and toxicological studies, as well as ambient exposure data and lake sediment data collected in Minnesota Iron Range communities. Collectively, the data provide consistent evidence that nonasbestiform amphibole minerals lack the carcinogenic potential exhibited by amphibole asbestos.

AbstractWe review approaches for characterizing "peak" exposures in epidemiologic studies and methods for incorporating peak exposure metrics in dose–response assessments that contribute to risk assessment. The focus was on potential etiologic relations between environmental chemical exposures and cancer risks. We searched the epidemiologic literature on environmental chemicals classified as carcinogens in which cancer risks were described in relation to "peak" exposures. These articles were evaluated to identify some of the challenges associated with defining and describing cancer risks in relation to peak exposures. We found that definitions of peak exposure varied considerably across studies. Of nine chemical agents included in our review of peak exposure, six had epidemiologic data used by the U.S. Environmental Protection Agency (US EPA) in dose–response assessments to derive inhalation unit risk values. These were benzene, formaldehyde, styrene, trichloroethylene, acrylonitrile, and ethylene oxide. All derived unit risks relied on cumulative exposure for dose–response estimation and none, to our knowledge, considered peak exposure metrics. This is not surprising, given the historical linear no‐threshold default model (generally based on cumulative exposure) used in regulatory risk assessments. With newly proposed US EPA rule language, fuller consideration of alternative exposure and dose–response metrics will be supported. "Peak" exposure has not been consistently defined and rarely has been evaluated in epidemiologic studies of cancer risks. We recommend developing uniform definitions of "peak" exposure to facilitate fuller evaluation of dose response for environmental chemicals and cancer risks, especially where mechanistic understanding indicates that the dose response is unlikely linear and that short‐term high‐intensity exposures increase risk.

In der vorliegenden Studie wurde eine Recherche zur aktuellen toxikologischen bzw. epidemiologischen Datenlage von 20 in der Trinkwasserverordnung regulierten perfluorierten Alkylsubstanzen (⁠PFAS⁠, C4-C13 Carbon- und Sulfonsäuren) sowie 4 Ersatzstoffen (GenX, ADONA, 6:2 FTSA, C604) durchgeführt. Ziel war eine Aufbereitung dieser Daten als Grundlage für die toxikologische Bewertung der Substanzen mit Bezug auf ihr Vorkommen im Trinkwasser. Die erhobenen Daten sollen die Grundlagen für die Berechnung von gesundheitlich begründeten Leitwerten oder die Ableitung von Gesundheitlichen Orientierungswerten (GOW) für das Trinkwasser bilden. Die eigentliche Berechnung der Leitwerte und die Ableitung von GOW ist jedoch nicht Bestandteil dieser Studie.

In the present study, a search was carried out on the current toxicological and epidemiological data on 20 perfluorinated alkyl substances (⁠PFAS⁠, C4-C13 carboxylic and sulfonic acids) regulated in the Drinking Water Ordinance as well as 4 substitutes (GenX, ADONA, 6:2 FTSA, C604). The aim was to prepare this data as a basis for the toxicological assessment of the substances with regard to their occurrence in drinking water. The data collected is intended to form the basis for the calculation of health-related guide values ​​or the derivation of health-related indicator values ​​(HRIV, German GOW) for drinking water. However, the actual calculation of the hr- guide values ​​and the derivation of HRIV/GOW is not part of this study.