Relationship between simultaneous exposure to ergonomic risk factors and work-related lower back pain: a cross-sectional study based on the fourth Korean working conditions survey

BACKGROUND: It is well known that ergonomic risk factors and back pain are related. However, few studies have examined the relationship between simultaneous exposure to these risk factors and back pain in a Korean population. We aimed to investigate the relationship between simultaneous exposure to ergonomic risk factors and work-related lower back pain (LBP) based on the fourth Korean Working Conditions Survey (KWCS). METHOD: The fourth KWCS (2014) was used for this study. Chi-square tests and logistic regression were used to assess relationship between 5 ergonomic risk factors and work-related LBP. We also analyzed the relationship between simultaneous exposure to 2 risk factors and work-related LBP. RESULTS: All 5 ergonomic risk factors (fatigue-inducing and painful posture; lifting or moving people; dragging, pushing, or moving heavy objects; standing posture; and repetitive hand or arm movements) were significantly correlated with work-related LBP in the severe exposure group (adjusted odd ratios [aOR] 5.09, 95% confidence interval [CI] 4.46–5.83; aOR 1.98, 95% CI 1.62–2.42; aOR 2.09, 95% CI 1.82–2.40; aOR 1.79, 95% CI 1.60–2.01; aOR 2.04, 95% CI 1.82–2.30, respectively). When exposed to 2 risk factors simultaneously, the relationship between exposure and work-related LBP was not greater than exposure to only 1 risk factor in our study (usually exposed to ‘fatigue-inducing or painful posture’ aOR 2.17, 95% CI 2.02–2.34; high exposure to both ‘fatigue-inducing or painful posture’ and ‘dragging, pushing, or moving heavy objects’ aOR 2.00, 95% CI 1.82–2.20). CONCLUSIONS: There was a strong relationship between severe exposure to each ergonomic risk factor and work-related LBP. However, when exposed to 2 ergonomic risk factors simultaneously, the relationship between exposure and work-related LBP was not stronger than when exposed to only 1 risk factor in our study.

Hepatic Effect of Simultaneous Exposure to Nickel and Cadmium in Rats / 대한산업의학회지

OBJECTIVES: This research was intended to verify hepatic effect of simutaneously combined exposure of nickel chloride and cadmium chloride with IPRL(Isolated Perfused Rat Liver) method. METHODS: AST(aspartate aminotransferase), ALT(alanine aminotransferase), LDH(lactate dehydrogenase) and perfusion flow rate were used as the indicator of hepatotoxicity and oxygen consumption rate were used as the indicator of viability. 300(+/-50) g weighted rats were allocated randomly to each group (control group, 50 microM 200 microM separately exposure group of NiC1, and CdC1, simultaneously combined exposure group of NiC1 and CdC1) by 5, totally 35. Buffer which got out of liver was sampled and then biochemical indicator of hepatotoxicity was measured. In order to verify difference among groups, two way repeated ANOVA was used. With comparing mean summation of separate exposure group with mean of simultaneous exposure group, possibility that combined effect could be synergistic effect was verified. RESULTS: AST, ALT, LDH increased in both of separate exposure group and simultaneous exposure group. Perfusion flow rate and oxygen consumption rate decreased but statistically significant difference among groups was not found, In each exposure group, AST, ALT, LDH, oxygen consumption rate of simultaneous exposure group increased more than sum of separate exposure group after any sampling time. CONCLUSIONS: It was found that simultaneous combined effect could be synergistic effect through the biochemical indicator of hepatotoxicity.