The use of Benford's law for evaluation of quality of occupational hygiene data

Job-exposure matrix for historical exposures to rubber dust, rubber fumes and n-Nitrosamines in the British rubber industry

OBJECTIVES

To develop a quantitative historical job-exposure matrix (JEM) for rubber dust, rubber fumes and n-Nitrosamines in the British rubber industry for 1915-2002 to estimate lifetime cumulative exposure (LCE) for a cohort of workers with 49 years follow-up.

METHODS

Data from the EU-EXASRUB database-rubber dust (n=4157), rubber fumes (n=3803) and n-Nitrosamines (n=10 115) collected between 1977 and 2002-were modelled using linear mixed-effects models. Sample year, stationary/personal measurement, industry sector and measurement source were included as fixed explanatory variables and factory as random intercept. Model estimates and extrapolations were used to construct a JEM covering all departments in both sectors of the rubber manufacturing industries for the years 1915-2002. JEM-estimates were linked to all cohort members to calculate LCE. Sensitivity analyses related to assumptions about extrapolation of time trends were also conducted.

RESULTS

Changes in rubber dust exposures ranged from -6.3 %/year (crude materials/mixing) to -1.0 %/year (curing) and -6.5 %/year (crude materials/mixing) to +0.5 %/year (finishing, assembly and miscellaneous) for rubber fumes. Declines in n-Nitrosamines ranged from -17.9 %/year (curing) to -1.3 %/year (crude materials and mixing). Mean LCEs were 61 mg/m3-years (rubber dust), 15.6 mg/ m3-years (rubber fumes), 2483.2 µg/m3-years (n-Nitrosamines sum score), 18.6 µg/m3-years (N-nitrosodimethylamine) and 15.0 µg/m3-years (N-itrosomorpholine).

CONCLUSIONS

All exposures declined over time. Greatest declines in rubber dust and fumes were found in crude materials and mixing and for n-Nitrosamines in curing/vulcanising and preprocessing. This JEM and estimated LCEs will allow for evaluation of exposure-specific excess cancer risks in the British rubber industry.

An analysis of bibliometric indicators to JCR according to Benford's law

Journal Citation Reports (JCR) is the main source of bibliometric indicators known by the scientific community. This paper presents the results of a study of the distributions of the first and second significant digits according to Benford’s law (BL) of the number of articles, citations, impact factors, half-life and immediacy index bibliometric indicators in journals indexed in the JCR Sciences and Social Sciences Editions from 2007 to 2014. We also performed the data analysis to country’s origin and by journal’s category, and we verified that the second digit has a better adherence to BL. The use of the second digit is important since it provides a more sound, complete and consistent analysis of the bibliometric indicators.