Development of retrospective quantitative and qualitative job-exposure matrices for exposures at a beryllium processing facility

Peak Inhalation Exposure Metrics Used in Occupational Epidemiologic and Exposure Studies

Peak exposures are of concern because they can potentially overwhelm normal defense mechanisms and induce adverse health effects. Metrics of peak exposure have been used in epidemiologic and exposure studies, but consensus is lacking on its definition. The relevant characteristics of peak exposure are dependent upon exposure patterns, biokinetics of exposure, and disease mechanisms. The objective of this review was to summarize the use of peak metrics in epidemiologic and exposure studies. A comprehensive search of Medline, Embase, Web of Science, and NIOSHTIC-2 databases was conducted using keywords related to peak exposures. The retrieved references were reviewed and selected for indexing if they included a peak metric and met additional criteria. Information on health outcomes and peak exposure metrics was extracted from each reference. A total of 1,215 epidemiologic or exposure references were identified, of which 182 were indexed and summarized. For the 72 epidemiologic studies, the health outcomes most frequently evaluated were: chronic respiratory effects, cancer and acute respiratory symptoms. Exposures were frequently assessed using task-based and full-shift time-integrated methods, qualitative methods, and real-time instruments. Peak exposure summary metrics included the presence or absence of a peak event, highest exposure intensity and frequency greater than a target. Peak metrics in the 110 exposure studies most frequently included highest exposure intensity, average short-duration intensity, and graphical presentation of the real-time data (plots). This review provides a framework for considering biologically relevant peak exposure metrics for epidemiologic and exposure studies to help inform risk assessment and exposure mitigation.

Retrospective Exposure Assessment Methods Used in Occupational Human Health Risk Assessment: A Systematic Review

As part of the assessment and management of chemical risk and occupational hygiene, retrospective exposure assessment (REA) to chemical agents can be defined as the estimate of exposure associated with a person's work history. The fundamental problem underlying the reconstruction of the exposure is that of transforming this type of information in quantitative terms to obtain an accurate estimate. REA can follow various approaches, some of which are technically complicated and both time and resource consuming. The aim of this systematic review is to present the techniques mainly used for occupational REA. In order to carry out this evaluation, a systematic review of the scientific literature was conducted. Forty-four studies were identified (published from 2010 to date) and analyzed. In exposure reconstruction studies, quantitative approaches should be preferable, especially when estimates will be used in the context of health impact assessment or epidemiology, although it is important to stress how, ideally, the experimental data available for the considered scenario should be used whenever possible as the main starting information base for further processing. To date, there is no single approach capable of providing an accurate estimate of exposure for each reasonably foreseeable condition and situation and the best approach generally depends on the level of information available for the specific case. The use of a combination of different reconstruction techniques can, therefore, represent a powerful tool for weighting and integrating data obtained through qualitative and quantitative approaches, in order to obtain the best possible estimate.

Weight of epidemiological evidence for titanium dioxide risk assessment: current state and further needs

We address here the importance of epidemiological evidence in risk assessment and decision-making in Europe. To illustrate this, titanium dioxide (TiO₂) was used as a model compound. TiO₂ is widely used as an odorless white pigment and opacifying agent. A recent systematic review assessing the weight of evidence on the relationship between exposure to TiO₂ (all forms) and cancer in humans questions the assumptions that TiO₂ is an inert material of low toxicity. Based on this new data, France submitted a proposal to classify TiO₂ as a possible human carcinogen under the European regulation. The European Chemicals Agency Risk assessment committee concluded that TiO₂ (all forms) warrants a classification as a suspected human carcinogen via inhalation (Category-2) under the CLP regulation (for Classification, Labeling and Packaging of chemicals). No considerations was given to TiO₂ particle size, which may affect human health effects. Consequently, further epidemiological studies are needed to assess possible associations between different physical-chemical characteristics of TiO₂ exposures and their impact on human health. This would allow strengthening the evidence on which to build the most appropriate regulation and to guaranty safe use given any exposure route of any TiO₂ particle shape or size.

Reanalysis of Reported Associations of Beryllium and Lung Cancer in a Large Occupational Cohort

OBJECTIVE

The aim of this study was to verify and extend reported associations of beryllium exposure and lung cancer by reanalyzing data from a large occupational cohort at three beryllium processing plants.

METHODS

We used standardization and Poisson regression to evaluate the effect of cumulative and maximum exposure, unlagged, and lagged 10 years, adjusting for plant, employment tenure, and date of hire. Exposure was modeled either categorically or continuously using splines.

RESULTS

Categorical analyses displayed previously reported effect patterns, but not the spline analysis, which provided a more consistent picture of risk across all analyzed groups.

CONCLUSIONS

We found modestly but monotonically increasing risk in the full cohort, by duration of tenure, and within most subgroups defined by plant and date of hire. Regression-based point-wise confidence bands, however, did not clearly separate risk for low versus high exposure groups.

Occupational exposure to beryllium and cancer risk: a review of the epidemiologic evidence

There is controversy on whether occupational exposure to beryllium causes lung cancer. We conducted a systematic review of epidemiologic studies on cancer among workers exposed to beryllium, including a study of seven U.S. production plants which has been recently updated, a study of patients with beryllium disease (largely overlapping with the former study) and several smaller studies. A small excess mortality from lung cancer was detected in the large cohort, which was partially explained by confounding by tobacco smoking and urban residence. Other potential confounders have not been addressed. The excess mortality was mainly among workers employed (often for a short duration) in the early phase of the manufacturing industry. There was no relation with duration of employment or cumulative exposure, whereas average and maximum exposure were associated with lung cancer risk. The use of lagged exposure variables resulted in associations with lung cancer risk; however, these associations were due to confounding by year of birth and year of hire. The studies of beryllium disease patients do not provide independent evidence and the results from other studies do not support the hypothesis of an increased risk of lung cancer or any other cancer. Overall, the available evidence does not support a conclusion that a causal association has been established between occupational exposure to beryllium and the risk of cancer.