Snap-fit assembly and upper limb functional limitations in automotive production workers: a nested case-control study.

OBJECTIVES: The use of snap-fits in car-part assembling has developed into an industrial standard. Cross-sectional evidence indicates, however, that this assembling process might adversely affect workers' upper limb function. The objective of this study was to analyze incident cases of upper limb functional limitations (ULFL) in relation to exposure to snap-fit assembly. METHODS: We performed a nested case-control study within a population of 5139 blue-collar automotive production workers. Cases with ULFL detected during follow-up were matched with controls based on employment duration and investigated on their exposure to snap-fit assembly. By conditional logistic regression, we modeled the risk for ULFL according to person-years of exposure to snap-fit assembly, adjusted for gender and baseline BMI. RESULTS: Overall, 64 ULFL cases were detected during a follow-up of 20610.8 person-years (3.1 cases per 1000 person-years). Cases, matched with an average of 4 controls, had significantly longer exposure duration to snap-fit assembly compared with controls (M = 1.15 person-years, SD = 1.68 person-years vs. M = 0.41 person-years, SD = 1.25 person-years). One person-year of exposure to snap-fit assembly was associated with an approximate 20% risk increase of developing ULFLs (OR 1.23, 95% CI 1.08-1.39). CONCLUSIONS: We confirm an association between accumulated exposure to snap-fits in car-part assembling and upper limb musculoskeletal disorders. Company physicians should thus be vigilant to symptoms of musculoskeletal disorders of the upper limbs in snap-fit assembly and support the development of threshold values for snap-fit insertion forces.

Shift work and hypertension: Prevalence and analysis of disease pathways in a German car manufacturing company.

BACKGROUND: Hypertension and cardiovascular disease (CVD) may share a similar pathophysiology. Despite shift workers' CVD excess risk, studies on shift work and hypertension are inconclusive. METHODS: Blood pressure and shift status for 25,343 autoworkers were obtained from medical check-ups and company registers. Cross-sectional associations modeling the total effect from shift work (day shifts, shift work without nights, rotating shift work with nights, and night shifts) on hypertension were assessed. By sequential adjustments, the influence of behavioral, psychosocial, and physiological factors on the total effect was examined, with subsequent mediation and moderation analyses. RESULTS: Adjusted for confounders, shift work without nights (vs. day shifts) was significantly associated with hypertension (OR 1.15, 95%CI 1.02-1.30). The total effect was mediated by BMI, physical inactivity, and sleep disorders. No moderation of the total effect by behaviors was found. CONCLUSION: The association between shift work and hypertension seems mainly attributable to behavioral mechanisms.

Phthalate exposure during cold plastisol application--a human biomonitoring study.

The phthalates DEHP (Diethylhexyl phthalate), DiNP (Diisononyl phthalate) and DiDP (Diisodecyl phthalate) are constituents of plastisols. We sought to obtain first data on occupational exposures to the above phthalates by analyzing their metabolites in pre- and post-shift urine samples from 5 workers in a car manufacturing plant engaged in seam sealing with a DINP based plastisol. Pre-shift samples were collected after a work-free period of at least 2 days. As a comparison group we investigated 10 employees from the same plant. The comparison group had phthalate exposures in the range of the general German population. All plastisol workers had post shift values of DiNP and DiDP metabolites that were approx. 20-times higher, and pre-shift values that were approx. 5-10 times higher than those of the general background exposure. Post-shift values of DiNP metabolites were (median [maximum]: OH-MiNP: 117 [442] µg/L; oxo-MiNP: 44.3 [175] µg/L; carboxy-MiNP: 57.8 [286]µg/L), pre shift values were (OH-MiNP: 26 [164] µg/L; oxo-MiNP 12.9 [68.6] µg/L; carboxy-MiNP: 32.3 [103] µg/L), compared to the comparison group (OH-MiNP: 6.2 [33]µg/L; oxo-MiNP: 2.8 [16] µg/L; carboxy-MiNP: 6.5 [31] µg/L). DiDP values were generally lower. Regarding DEHP we found no significant work related exposure. The dermal exposure route might play an important role for phthalates in plastisols, with possible influences on distribution and elimination kinetics and therefore data interpretation.

Shift work, chronodisruption and cancer?--The IARC 2007 challenge for research and prevention and 10 theses from the Cologne Colloquium 2008.

In October of 2007, an IARC panel of 24 scientists systematically evaluated epidemiologic, experimental, and mechanistic data and concluded that shift work that involves circadian or chronodisruption is probably carcinogenic in humans. In view of the possible scope of the problem--shift work is widespread and unavoidable on one hand and breast cancer and prostate cancer, which may be causally associated with chronodisruption, are epidemic worldwide on the other--German representatives of science and occupational medicine discussed the experimental and epidemiologic background and possible implications of the challenge identified by the International Agency for Research on Cancer (IARC) at a colloquium in Cologne in September 2008. This overview summarizes the key ideas presented at the Cologne Colloquium and offers 10 theses concerning the need for targeted studies and the necessity to develop possible means of prevention.

Biological monitoring of welders exposed to aluminium.

To evaluate an adequate strategy for biological monitoring of aluminium (Al), a group of 62 Al welders (age in 1999: 23-51 years, median 35 years) was surveyed annually from 1999 to 2003 by determination of pre- and post-shift Al in urine and plasma. Biomonitoring was supplemented by personal air measurements of the total dust concentration. The welders' internal exposure was compared to the exposure of 60 non-exposed assembly workers (age in 1999: 21-51 years, median: 36 years) who were surveyed in 1999, 2001 and 2003. Having a nearly constant dust exposure, median concentrations of Al in urine (Al in plasma) of the welders decreased from 40.1 microg/g to 19.8 microg/g creatinine (8.7 to 4.6 microg/l). For the control group the median levels of Al in urine (plasma) ranged from 4.8 microg/g to 5.2 microg/g creatinine (2.4-4.3 microg/l) indicating a higher sensitivity for the marker Al in urine. No systematic differences have been found between pre- and post-shift internal exposure. This might be caused by the slow elimination kinetics and low systemic bioavailability of Al. A correlation analysis did not yield close relationships between dust exposure, Al in plasma and Al in urine underlining the importance of biomonitoring for assessment of Al exposure.