Reported exposures to respirable crystalline silica during construction tasks and guidance for harmonizing future research.

Airborne respirable crystalline silica (RCS) has been a widely recognized hazard in the United States for nearly 100 years, yet it continues to pose a risk to construction tradespersons, among others. RCS exposures vary widely depending on site conditions and tools and materials used. The proper use of engineering, administrative, and personal protective equipment (PPE) controls can effectively reduce exposure to RCS. Historically, others have reviewed available RCS exposure data among construction trades and reported that there were considerable data gaps and variability that needed to be addressed. This current assessment aimed to synthesize available peer-reviewed exposure studies to determine potential RCS exposures during the use of common construction materials and evaluate to what extent data gaps and variability persist. Twenty-eight studies were identified that reported RCS exposure during construction tasks. After conversion to the unit of µg/m3, reported measurements from samples collected for varying durations ranged from 6.0 to 75,500 µg/m3 for work with concrete, 80 to 4,240 µg/m3 for work with brick, <59 to 10,900 µg/m3 for work with mortar, 90 to 44,370 µg/m3 for work with engineered stone, and 70 to 380 µg/m3 for work with roof tile. To better facilitate pooling data across studies, future researchers should report their sample duration, clarify how time-weighted average (TWA) exposure data are calculated, report the silica content of the material being manipulated, and specify whether samples were collected while the task was performed in isolation or on a worksite where other silica-containing materials were also actively handled. When reporting results as respirable quartz, it is important to note whether any other polymorphic forms of silica were detected. It is ultimately the employer's responsibility to train employees and monitor and control RCS exposures on construction worksites. To do this effectively, it is important to have a clear understanding of the tasks, materials, and site conditions where intervention is most urgently needed.

A comparative evaluation of dietary exposure to glyphosate resulting from recommended U.S. diets.

Since its commercial introduction in 1974, national and international regulatory agencies have consistently reported no human health concerns associated with the herbicide glyphosate when used according to label directions. However, in 2015, the International Agency for Research on Cancer (IARC) classified glyphosate as a probable human carcinogen. Despite IARC being the sole outlier in its conclusion, dietary exposure to glyphosate remains a health concern to some members of the public. While glyphosate residues have been detected in foods, it is unclear whether a specific eating pattern substantially contributes to glyphosate exposure. Therefore, dietary glyphosate intake was determined for three eating patterns recommended in the U.S. The 95th percentile of glyphosate ingestion at 2,000 calories/day for adults for the U.S.-Style, Mediterranean-Style, and Vegetarian eating patterns ranged from 38 to 960, 39 to 1100, and 39 to 880 µg/day, respectively. No significant differences were observed in glyphosate intake between the dietary styles, and the 95th percentile glyphosate intakes were well below the current U.S. EPA chronic oral reference dose (RfD) of 0.1 mg/kg/day. Our data demonstrate that ingestion of certain high residue foods, particularly grains and legumes, is a driver of total dietary glyphosate body burden regardless of dietary style.

Pilot study evaluating inhalation and dermal glyphosate exposure resulting from simulated heavy residential consumer application of Roundup®.

OBJECTIVES: The purpose of this study was to evaluate the individual contributions of inhalation and dermal exposures to urinary glyphosate levels following the heavy residential consumer application of a glyphosate-containing herbicide. METHODS: A pilot study was conducted in which each participant mixed and continuously spray-applied 16.3 gallons of a 0.96% glyphosate-containing solution for 100 min using a backpack sprayer. Twelve participants were divided evenly into two exposure groups, one equipped to assess dermal exposure and the other, inhalation exposure. Personal air samples (n = 12) and dermal patch samples (n = 24) were collected on the inhalation group participants and analyzed for glyphosate using HPLC-UV. Serial urine samples collected 30-min prior to application and 3-, 6-, 12-, 24-hr (inhalation and dermal groups) and 36-hr (dermal group only) post-application were analyzed for glyphosate and glyphosate's primary metabolite (AMPA) using HPLC-MS/MS. RESULTS: The mean airborne glyphosate concentration was 0.0047 mg/m3, and the mean concentrations of glyphosate for each applicator's four patch samples ranged from 0.04 µg/mm2 to 0.25 µg/mm2. In general, urinary glyphosate, AMPA, and total effective glyphosate levels were higher in the dermal exposure group than the inhalation exposure group, peaked within 6-hr following application, and were statistically indistinguishable from background at 24-hr post-application. CONCLUSIONS: This is the first study to characterize the absorption and biological fate of glyphosate in residential consumer applicators following heavy application. The results of this pilot study are consistent with previous studies that have shown that glyphosate is rapidly eliminated from the body, typically within 24 hr following application.

An updated evaluation of potential health hazards associated with exposures to asbestos-containing drywall accessory products.

Following a previously published (2012) evaluation of the potential health hazards related to the use of asbestos-containing drywall accessory products, additional information regarding asbestos exposures during the use of accessory products, as well as studies of chrysotile asbestos risk as a function of exposure, have been published in the peer-reviewed literature. The purpose of this analysis is to update the original evaluation with this new information. It was previously estimated that a professional drywaller performing joint compound-associated tasks could have a lifetime cumulative chrysotile exposure of 12-26 f/cc-year. Using conservative assumptions regarding airborne asbestos levels during different drywalling tasks, task duration, and job tenure, we found that a range of 4.3-36.3 f/cc-year is a plausible estimate of a career drywaller's cumulative asbestos exposure from historical joint compound use. The estimated range for bystander exposures would be below (sometimes significantly below) this range depending on the frequency and duration of work near drywallers. Further, the estimated drywaller and bystander total fiber exposures were well below a recently published "no-observed adverse effect level, best estimate" for predominately chrysotile exposures of 89-168 f/cc-year for lung cancer and 208-415 f/cc-year for mesothelioma. We also determined that, even if the chrysotile or possibly talc ingredients in the drywall products had contained asbestiform tremolite, the cumulative tremolite exposures would have been well below a recently published tremolite no-effect level of 0.5-2.6 f/cc-year. Based on our calculations, typical drywall work using asbestos-containing drywall accessory products is not expected to increase the risk of asbestos-related lung cancer or mesothelioma. These conclusions are consistent with the lack of epidemiological evidence that drywall work resulted in an increased incidence of asbestos-related disease in the drywall trades.

The Cancer Risk Associated with Residential Exposure to Soil Containing Radioactive Coal Combustion Residuals.

Coal combustion residuals (CCRs) are composed of various constituents, including radioactive materials. The objective of this study was to utilize methodology on radionuclide risk assessment from the Environmental Protection Agency (EPA) to estimate the potential cancer risks associated with residential exposure to CCR-containing soil. We evaluated potential radionuclide exposure via soil ingestion, inhalation of soil particulates, and external exposure to ionizing radiation using published CCR radioactivity values for 232 Th, 228 Ra, 238 U, and 226 Ra from the Appalachia, Illinois, and Powder River coal basins. Mean and upper-bound cancer risks were estimated individually for each radionuclide, exposure pathway, and coal basin. For each radionuclide at each coal basin, external exposure to ionizing radiation contributed the greatest to the overall risk estimate, followed by incidental ingestion of soil and inhalation of soil particulates. The mean cancer risks by route of exposure were 2.01 × 10-6 (ingestion), 6.80 × 10-9 (inhalation), and 3.66 × 10-5 (external), while the upper bound cancer risks were 3.70 × 10-6 (ingestion), 1.18 × 10-8 (inhalation), and 6.15 × 10-5 (external), using summed radionuclide-specific data from all locations. The upper bound cancer risk from all routes of exposure was 6.52 × 10-5 . These estimated cancer risks were within the EPA's acceptable cancer risk range of 1 × 10-6 to 1 × 10-4 . If the CCR radioactivity values used in this analysis are generally representative of CCR waste streams, then our findings suggest that CCRs would not be expected to pose a significant radiological risk to residents living in areas where contact with CCR-containing soils might occur.