Synergistic interaction between MMP-3, VDR gene polymorphisms and occupational risk factors on lumbar disc degeneration / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To explore the synergistic interaction between MMP-3,VDR gene polymorphisms and occupational risk factors on lumbar disc degeneration.</p><p><b>METHODS</b>A case-control study including 178 cases of lumbar disc degeneration and 284 controls was carried out through questionnaire and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technology. Additive model was used to analyze the synergistic interaction between gene polymorphisms and occupational risk factors.</p><p><b>RESULTS</b>The non-conditional logistic regression analysis showed that bending/twisting, whole-body vibration, heavy physical workload, alleles 5A of MMP-3 (6A5A/5A5A) and A of VDR-Apa (AA/Aa) were significantly associated with lumbar disc degeneration(OR = 4.06, 8.96, 5.46, 1.96 and 1.70, respectively, P < 0.05). There were synergistic interactions between the mutation genotype 5A of MMP-3 and whole-body vibration exposure, between the mutation genotype 5A of MMP-3 and bending/twisting, and between the mutation genotype A of VDR-Apa and whole-body vibration exposure (SI: 13.27, 2.91 and 2.35 respectively, P < 0.05).</p><p><b>CONCLUSION</b>People with the mutation genotypes 5A of MMP-3 and/or A of VDR-Apa may have the increased risk of developing lumbar disc degeneration if they are exposed to whole-body vibration and/or bending/twisting.</p>

Predictors of return to work after occupational injury in a locomotive enterprise / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To identify the potential determinants of return to work (RTW) following work-related injury.</p><p><b>METHODS</b>A historical cohort of workers with occupational injury in a state-owned locomotive vehicle company in central China was followed up for RTW. Demographic, employment and medical information was retrieved from the company archival documents; and post-injury information was interviewed by questionnaires. Univariate analysis and Cox Regression Model were used to examine the associations between potential determinants and outcomes of RTW.</p><p><b>RESULTS</b>Three hundred of the 323 included cases (92.9%) eventually returned to work after the median absence of 43 days (average of 49.2 days). Factors from socio-demographic, clinical, economic and psychological domains were found affecting RTW in the univariate analyses. The multivariate analysis indicated that age, injury severity, injury locus, injury nature, pain in the injury locus, self-reported health status and pre-injury monthly salary were significant determinants of RTW.</p><p><b>CONCLUSIONS</b>There are multidimensional factors affecting RTW after occupational injury. Proper clinical treatment and rehabilitation, as well as economic and social support to facilitate workers' RTW would be the priorities for intervention. Future studies should be conducted in a larger representative sample to confirm the findings and to develop a multidisciplinary intervention strategy towards promoting RTW.</p>

A psychophysical evaluation of NIOSH Lifting Equation in a Chinese young male population: a pilot study / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To determine the maximum acceptable weight of lift (MAWL) in a Chinese young male population, and examine whether the revised weight limit recommended by the US. National Institute for Occupational Safety and Health can be used for Chinese workers.</p><p><b>METHODS</b>Eleven young male college students participated in the experiment. The psychophysical approach was used to determine the MAWL with the different frequencies of lift, the heart rate and the self-evaluation. The weight was lifted from the floor to the work-table (760 mm). The results were compared with the recommended weight limit (RWL) and the MAWL by Snook.</p><p><b>RESULTS</b>The MAWL of young male was 34.1 kg while the MAWL with frequency of 1, 4 and 8/min was 17.4, 14.7 and 12.2 kg respectively. The overall MAWL were lower than RWL of NIOSH and the results of Snook.</p><p><b>CONCLUSION</b>The NIOSH 1991 equation such as load constant and frequency multiple should be revised when the NIOSH limits is used in Chinese population.</p>

Dose-respones relationship between daily total fluoride intake and prevalence of osteofluorosis / 中国地方病学杂志

Objective To investigate the daily total fluoride intake in relating to the prevalence of skeletal fluorosis in two villages in Jiangsu Province,in order to provide the scientific evidences for the control and prevention of endemic fluorosis.Methods Adults sampled from a high-fluoride Village,Wamiao,and a low-fluoride Village,Xinhuai,were surveyed in this study according to the fluoride concentration in their household shallow well.The average daily total fluoride intake from difierent sources and the skeletal fluorosis were investigated in each subject.Then the subjects from two villages were allocated into five subgroups(＜2.00,2.00～,3.00～,4.00～,≥5.00 mg/d),the relation fluoride intake and prevalence of osteofluorosis was analyzed.Results The prevalence of skeletal fluorosis in Wamiao Village was 31.06%(41/132),but no skeletal fluorosis case(0/35)was found in Xinhuai Village.According to the daily total fluoride intake,subjects with higher daily total fluoride intake tended to associated with a higher prevalence of skeletal fluorosis in a significant dose-response relationship(regression equation:y=2.624-6.855x+3.424x2:r=0.997).The benchmark dose lower limitation of daily total fluoride intake with 95% confidencewas 2.50 mg/d calculated according to this dose-response relationship,the reference dose(RfD)was 2.50 mg/d.In Wamiao Village a significant difference was also found between daily total fluoride intake in 41 subjects[(5.09±1.20)mg/d]with X-ray detectable skeletal fluorosis and in 91 subjects[(3.08±1.12)mg/d]without X-ray detectable skeletal fluorosis(t=-9.32,P＜0.01).Conclusions These findings indicate that the daily total fluoride intake has a significant dose-response relationship with the prevalence of skeletal fluorosis in an endemic fluorosis area associated with high-fluoride drinking water;and the RfD in this study was lower than that in the national standard of"Chinese hygienic standard for daily total fluoride intake(WS/T 87-1996)"(3.50 mg/d).

Effects of dusts on workers' health in enzyme production plants / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To assess the health effects of dusts in enzyme production plants.</p><p><b>METHODS</b>The concentration of enzyme-containing dusts, the enzyme and the wheat-containing dusts and their health effects on workers were investigated in three enzyme production plants. Air samples were collected by high volume sampler and personal sampler. Total dust was weighed and its content of enzyme was analyzed by enzyme activity method. Health effects were assessed by the questionnaire, the pulmonary function and the skin prick test.</p><p><b>RESULTS</b>It was found that the geometric mean of enzyme-containing dust was 8.91 mg/m(3), the industrial enzyme was 1.68 mg/m(3), and the wheat-containing dust was 6.93 mg/m(3). The enzyme-containing dust higher than 20 mg/m(3) caused eye symptoms. The wheat-containing dust at 6.93 mg/m(3) might result in skin and nose symptoms. The sensitization could be observed in enzyme and wheat exposed workers.</p><p><b>CONCLUSION</b>Adverse effects may arise for the health of the workers if the concentration of enzyme-containing dusts and the wheat-containing dusts is up to a certain limit and it is necessary to make the limit of these indexes.</p>

Isometric muscle strength measurements and assessment: a pilot study / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To determine the anthropometric parameters and the isometric muscle strength in a working population sample in China, and to investigate the relationship between muscle strength and individual attributes, such as age, gender, height and weight.</p><p><b>METHODS</b>The study population consisted of 146 male and 47 female people including workers, administrators and college students. Four types of muscle strength, i.e., handgrip, arm lift, shoulder lift, and torso pull, were measured.</p><p><b>RESULTS</b>Left handgrip, right handgrip, arm lift, shoulder lift and torso pull of male workers were (42.07 +/- 7.20), (43.92 +/- 7.14), (26.79 +/- 4.64), (33.79 +/- 6.88), (88.56 +/- 17.98) kg, respectively while those of female workers were (21.29 +/- 5.09), (23.26 +/- 5.47), (13.29 +/- 3.37), (18.52 +/- 4.01), (41.06 +/- 12.04) kg, respectively. The female's strength was about 50% lower than the male's. The strength in the 40 approximately years old group was higher than that in other age groups. There were significant positive correlation between the gender and the isometric strength as well as between the body weight and the isometric strength. If the body weight served as the corrected parameter, there was no significant difference in the handgrip among the groups (P < 0.05), but the torso pull of male workers > college students > administrators. All relative muscle strengths except the torso pull were similar for all age groups.</p><p><b>CONCLUSION</b>The body weight as the independent variable can be used for establishing the predictive equation of the muscle strength. Calculation of the relative muscle strength can relieve the interference of the body weight for the muscle strength.</p>

Study on the application of benchmark dose and biological monitoring indexes of fluorides in drinking water / 中华预防医学杂志

<p><b>OBJECTIVE</b>By using Benchmark Dose (BMD) approach to explore the relations among drinking water fluoride, urine fluoride, serum fluoride and dental fluorosis; and to evaluate the significance of urine fluoride and serum fluoride in control and prevention of endemic fluorosis.</p><p><b>METHODS</b>512 children (290 in Xinhuai Village, 222 in Wamiao Village) aged 8-13 years were recruited in the study. Epidemiological methods were used to investigate the prevalence of dental fluorosis, and the levels of urine fluoride, serum fluoride, and drinking water fluoride in superficial well. The children were divided into six subgroups by the concentration of fluoride in drinking water: < 0.5 mg/L, 0.5-mg/L, 1.0-mg/L, 2.0-mg/L, 3.0-mg/L and > or = 4.0 mg/L.</p><p><b>RESULTS</b>There was significant dose-response relationship between the drinking water fluoride and the prevalence of dental fluorosis or the prevalence of defect dental fluorosis. The BMDLs (Benchmark Dose Lower Bound) were 1.01 and 1.30 mg/L, respectively. Urine fluoride and serum fluoride also had significant dose-response relationship to the prevalence of dental fluorosis or defect dental fluorosis. The correlation coefficient between drinking water fluoride and urine fluoride was 0.717, and it was 0.855 between drinking water fluoride and serum fluoride, and 0.617 between urine fluoride and serum fluoride.</p><p><b>CONCLUSIONS</b>The currently national standard of fluoride in drinking water in China is safe and reasonable. As a biological monitoring index, the levels of fluoride in serum may be more useful than that in urine in the control and prevention of endemic fluorosis.</p>

Study on lifting-related musculoskeletal disorders among workers in metal processing / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To investigate lifting-related musculoskeletal disorders in metal processing, to analyze the risk factors, and to study the validity and feasibility of using NIOSH lifting equation in China.</p><p><b>METHODS</b>The questionnaires of semi-structured interview, the Ovako Working Posture Analysing System (OWAS) postural analysis and variables of the NIOSH equation were applied to the study. The study population consisted of 69 workers mainly involved in manual materials handling (MMH), categorized as Job A; and 51 machinery workers, served as controls, that were less MMH task involved, as Job B.</p><p><b>RESULTS</b>The prevalence of low back pain (LBP), which was defined at least one episode lasting for more than 24 hours in the past 12 months, were 63.8% and 37.3% for Job A and Job B, respectively. However, the prevalence of LBP lasting for more than a week due to lifting were 26.09% and 5.88% for Job A and B, respectively. The proportion of awkward back postures were found higher in Job A than that of Job B (66% vs 63%, P < 0.05). The NIOSH Lifting Index (LI) was estimated to be 2.4 for Job A, and 0 < LI < 1 for Job B. The analysis of multiple regressions revealed that the repetitiveness of lifting and length of service had greatly attributed to the occurrence of LBP. The "composite load" (object weight x activity repetitiveness) had a significant adverse effect on lower back meaning that the objective weight remains an ingredient part of the risk.</p><p><b>CONCLUSION</b>The occurrence of LBP is not only related to the force load, but the repetitiveness of lifting and awkward postures. The method of OWAS observation and US-NIOSH equation are important tools in assessing characteristics and risk factors of LBP for MMH tasks. Further study aimed at developing an integral scheme for the assessment system is needed.</p>