Background: We developed a systematic, data-driven approach to estimate metrics of occupational exposure to lead to aid in epidemiologic analyses in a case-control study of kidney cancer. Methods: Probability of exposure to ten lead sources was assigned using decision rules developed from an extensive literature review and expert judgement. For jobs with ≥50% probability of exposure, we assigned source-specific frequency based on subjects’ self-reported task frequencies or means of subjects’ job-groups and source-specific intensity estimates of blood lead (μg/dL). Results: In our study, 18.7% of employed person-years were associated with high (≥80%) probability of exposure to any lead source. The most common medium (>50%) or high probability source of lead exposure was leaded gasoline (2.5% and 11.5% of employed person-years, respectively). The median blood lead attributed to occupational exposure was 3.1 μg/dL. Conclusions: These rules can aid in future studies after population-specific adaption for geographic differences and different exposure scenarios.
5G small cell antenna systems are among the latest technologies that support wireless communications by the transmission of radiofrequency (RF) signals. Coded RF signals in the range of 0.6 to 47 GHz from fixed small cell antennas supplement wireless communications from 3G and 4G wireless systems. This paper describes the propagation of RF signals from a pole-mounted 5G antenna and how the signal strength declines with distance for a representative installation operating at 39 GHz. The far field exposure from the antenna is compared to those from multiple natural and man-made RF sources. In the United States, RF exposure standards are issued by the Federal Communications Commission. We review the history and derivation of these standards in relation to other national and international standard-setting bodies. Some have raised concern as to whether sufficient health and safety studies have been performed on RF from 5G systems, but the commonality of RF frequencies up to 300 GHz enables health agencies and standard-setting bodies to assess the potential for effects across this frequency spectrum. A 5G RF signal does not have a different mode of action than a lower frequency communication signal; both involve tissue heating at sufficient field strengths. The key difference for 5G frequencies above 6 GHz is that the body's electrical properties better limit energy deposition to a shallow depth, largely confined to superficial layers of the skin. Research to date has not provided a reliable scientific basis to conclude that RF communication signals at 5G or other frequencies will cause or contribute to adverse health effects.
Objectives Occupational exposures in population-based case–control studies are increasingly being assessed using decision rules that link participants’ responses to occupational questionnaires to exposure estimates. We used a hierarchical process that incorporated decision rules and job-by-job expert review to assign occupational benzene exposure estimates in a US population-based case–control study of non-Hodgkin lymphoma. Methods We conducted a literature review to identify scenarios in which occupational benzene exposure has occurred, which we grouped into 12 categories of benzene exposure sources. For each source category, we then developed decision rules for assessing probability (ordinal scale based on the likelihood of exposure > 0.02 ppm), frequency (proportion of work time exposed), and intensity of exposure (in ppm). The rules used the participants’ occupational history responses and, for a subset of jobs, responses to job- and industry-specific modules. For probability and frequency, we used a hierarchical assignment procedure that prioritized subject-specific module information when available. Next, we derived job-group medians from the module responses to assign estimates to jobs with only occupational history responses. Last, we used job-by-job expert review to assign estimates when job-group medians were not available or when the decision rules identified possible heterogeneous or rare exposure scenarios. For intensity, we developed separate estimates for each benzene source category that were based on published measurement data whenever possible. Frequency and intensity annual source-specific estimates were assigned only for those jobs assigned ≥75% probability of exposure. Annual source-specific concentrations (intensity × frequency) were summed to obtain a total annual benzene concentration for each job. Results Of the 8827 jobs reported by participants, 8% required expert review for one or more source categories. Overall, 287 (3.3%) jobs were assigned ≥75% probability of exposure from any benzene source category. The source categories most commonly assigned ≥75% probability of exposure were gasoline and degreasing. The median total annual benzene concentration among jobs assigned ≥75% probability was 0.11 ppm (interquartile range: 0.06–0.55). The highest source-specific median annual concentrations were observed for ink and printing (2.3 and 1.2 ppm, respectively). Conclusions The applied framework captures some subject-specific variability in work tasks, provides transparency to the exposure decision process, and facilitates future sensitivity analyses. The developed decision rules can be used as a starting point by other researchers to assess occupational benzene exposure in future population-based studies.
Purpose of review Exposure assessment efforts in population-based studies are increasingly incorporating measurements. The published literature was reviewed to identify the measurement sources and the approaches used to incorporate measurements into these efforts. Recent findings The variety of occupations and industries in these studies made collecting participant-specific measurements impractical. Thus, the starting point was often the compilation of large databases of measurements from inspections, published literature, and other exposure surveys. These measurements usually represented multiple occupations, industries, and worksites, and spanned multiple decades. Measurements were used both qualitatively and quantitatively, dependent on the coverage and quality of the data. Increasingly, statistical models were used to derive job-, industry-, time period-, and other determinant-specific exposure concentrations. Summary Quantitative measurement-based approaches are increasingly replacing expert judgment, which facilitates the development of quantitative exposure-response associations. Evaluations of potential biases in these measurement sources, and their representativeness of typical exposure situations, warrant additional examination.
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