[Effects of rush mat dust exposure and smoking on workers' FEV1.0].

OBJECTIVE: To study the effect of smoking and rush-mat dust exposure on pulmonary function. METHOD: 122 rush-mat dust exposed workers and 118 controls without dust exposure were selected. Questionnaire and FEVY1.0 measurement were performed on them. RESULTS: For dust exposure, FEV1.0% of cases (81.8% +/- 13.9%) was statistically lower than controls (95.9% +/- 15.3%) (t = -7.49, P < 0.01), the abnormal rate of FEV1.0% was 46.7% (57/122) for cases, statistically higher than controls (8.5%, 10/118), chi2 = 43.6, P < 0.01. For smoking, FEV1.0% of cases (82.02% +/- 12.9%) was statistically lower than controls (93.33% +/- 12.4%), t = -5.18, P < 0.05, the abnormal rate of FEV1.0% is 55.9% for cases, statistically higher than controls (16.7%), chi2 = 22.2, P < 0.05. The exposing ages of workers has negative correlation with FEV1.0% (R(S1) = -0.299, P = 0.0008). Exposure and smoking could affect FEV1.0% (Fe = 259.06, P < 0.01, F(s) = 42.42, P < 0.01), and their interactive effect on FEV1.0% was greater than single ones (F = 34.70, P < 0.01). CONCLUSION: Rush-mat dust exposure, smoking and their interaction have influence on FEV1.0%.

[Synergistic interaction between MMP-3, VDR gene polymorphisms and occupational risk factors on lumbar disc degeneration].

OBJECTIVE: To explore the synergistic interaction between MMP-3,VDR gene polymorphisms and occupational risk factors on lumbar disc degeneration. METHODS: 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. RESULTS: 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). CONCLUSION: 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.

[Effect of bisphenol A on semen quality of exposed workers: a pilot study].

OBJECTIVE: To explore the semen quality of the workers exposed to the xenoestrogen bisphenol A (BPA) was explored. METHODS: A cross-sectional study of 20 BPA exposed and 16 control workers with similar age, physical activities was performed. Tests included quantifying BPA in blood samples and investigating the quantity and quality of semen. Semen parameters were determined with the method recommended by WHO. RESULTS: 94.4% exposed workers were found BPA in blood, and the median was 101.94 microg/L. However, only 18.8% control subjects were found BPA in blood, and the median level was 0 microg/L. The sperm density of exposed workers [(68.65 +/- 44.00) x 10(6)/ml] was significantly lower than that of control [(118.56 +/- 98.36) x 10(6)/ml]. Relationship analysis showed the positive relationships (r = 0.44, P < 0.01) between the sperm with quick forward progression and BPA level in blood, negative relationships between the percentage of normal sperm and BPA level in blood (r = -0.62, P = 0.01). CONCLUSION: BPA could affect the sperm density, and may influence the semen quality. More research should be performed on the effect and the mechanism of BPA on man.

[A psychophysical evaluation of NIOSH Lifting Equation in a Chinese young male population: a pilot study].

OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: The NIOSH 1991 equation such as load constant and frequency multiple should be revised when the NIOSH limits is used in Chinese population.

Lung disorders of workers exposed to rush smear dust in China.

The aim of this study was to evaluate the lung disorders of the workers exposed to rush smear dust. A cross sectional study was carried out on 1,709 current workers (788 male, 921 female) in 80 factories. All subjects were asked by questionnaire, and health examination including chest X-ray was conducted for 661 workers in 35 factories. Lung function test was also examined for 119 non-smoking males among 661 subjects. Dust samplings were collected and total and respirable dust concentrations at 127 spots in 35 factories were measured. The geometric mean dust concentration in the workshops was up to 20.00 mg/m(3), and the geometric mean respirable dust concentration reached 8.22 mg/m(3). The mean quartz concentration of accumulated dust was 29.2%. The prevalence of radiographic small opacities profusion category > or = 1/0, according to the ILO 1980 Classification System, was 2.6% among 661 employees. One worker was found to have pneumoconiotic findings of 2/2 profusion accompanied with large opacity. The prevalence of pneumoconiosis (1/0 or more) correlated with cumulative dust exposure (r=0.192, p<0.0001). The similar relationship was found between the prevalence rate of cough or sputa and worksite dust concentration. In non-smokers, a positive association was found between the prevalence of cough and occupational exposure duration (r=0.080, p=0.004). Approximately 19.3% and 34.5% of employees suffered from respiratory impairment for FVC and FEV1.0, respectively. This is the first report of "rush" pneumoconiosis in China. Rush mat workers were found to be at high risk for pneumoconiosis, a preventable disease. Our results showed a dose-response relationship between rush-mat dust level and the prevalence of pneumoconiosis. Similar relationship between the prevalence of cough and sputum and the work duration was found for non-smoking workers but not for smoking workers.

[Isometric muscle strength measurements and assessment: a pilot study].

OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Study on musculoskeletal disorders in a machinery manufacturing plant.

Musculoskeletal disorders and related risk factors in machinery manufacturing were investigated using interviews, postural analysis, and the revised National Institute for Occupational Safety & Health lifting equation. Sixty-nine workers involved in manual materials handling (Job A) and 51 machinery workers less involved with manual material-handling tasks (Job B) were studied. Low back pain (LBP) (at least one episode lasting for 24 hours or more in past 12 months) prevalence rates were 63.8% and 37.3% for Jobs A and B, respectively. Prevalence rates of LBP every day for a week or more attributed to lifting were 26.09% and 5.88% for Jobs A and B, respectively. Multiple regression analysis revealed that lifting repetitiveness and work age contributed to the occurrence of LBP. The "composite load" (object weight x activity repetitiveness) had a significant adverse effect on LBP.

[Study on lifting-related musculoskeletal disorders among workers in metal processing].

OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Radiation dose in the thyroid and the thyroid cancer risk attributable to CT scans for pediatric patients in one general hospital of China.

OBJECTIVE: To quantify the radiation dose in the thyroid attributable to different CT scans and to estimate the thyroid cancer risk in pediatric patients. METHODS: The information about pediatric patients who underwent CT scans was abstracted from the radiology information system in one general hospital between 1 January 2012 and 31 December 2012. The radiation doses were calculated using the ImPACT Patient Dosimetry Calculator and the lifetime attributable risk (LAR) of thyroid cancer incidence was estimated based on the National Academies Biologic Effects of Ionizing Radiation VII model. RESULTS: The subjects comprised 922 children, 68% were males, and received 971 CT scans. The range of typical radiation dose to the thyroid was estimated to be 0.61-0.92 mGy for paranasal sinus CT scans, 1.10-2.45 mGy for head CT scans, and 2.63-5.76 mGy for chest CT scans. The LAR of thyroid cancer were as follows: for head CT, 1.1 per 100,000 for boys and 8.7 per 100,000 for girls; for paranasal sinus CT scans, 0.4 per 100,000 for boys and 2.7 per 100,000 for girls; for chest CT scans, 2.2 per 100,000 for boys and 14.2 per 100,000 for girls. The risk of thyroid cancer was substantially higher for girls than for the boys, and from chest CT scans was higher than that from head or paransal sinus CT scans. CONCLUSIONS: Chest CT scans caused higher thyroid dose and the LAR of thyroid cancer incidence, compared with paransal sinus or head CT scans. Therefore, physicians should pay more attention to protect the thyroid when children underwent CT scans, especially chest CT scans.

Matrix metalloproteinase-3 and vitamin d receptor genetic polymorphisms, and their interactions with occupational exposure in lumbar disc degeneration.

OBJECTIVES: To investigate the occupational and genetic risk factors inducing lumbar disc degeneration in a Chinese population, and to explore their synergistic interactions. METHODS: A case-control study involving 178 low back pain patients with lumbar disc degeneration and 284 controls was carried out. Five types of work-related factors were investigated using questionnaires. Polymerase chain reaction and restriction fragments length polymorphism was used to detect the polymorphisms of MMP-3 (matrix metalloproteinase-3)(rs731236), VDR-Taq (vitamin D receptor-Taq) and VDR-Apa (vitamin D receptor-Apa)(rs35068180). Rothman's synergy index was used to measure the synergistic interactions between gene polymorphisms and occupational risk factors. RESULTS: Family history of lumbar disc diseases, back injury history, whole-body vibration, bending/twisting, heavy physical workload, age, mutation alleles 5A of MMP-3 and A of VDR-Apa were significantly associated with lumbar disc degeneration (OR=12.70, 11.79, 8.96, 5.46, 1.05, 1.96 and 1.70, respectively, p<0.05). Synergistic interactions existed between the mutation allele 5A of MMP-3 and whole-body vibration exposure, the mutation allele 5A of MMP-3 and bending/twisting, and the mutation allele A of VDR-Apa and bending/twisting (SI=13.27, 2.91, 2.35, respectively, p<0.05). CONCLUSIONS: The results of this study suggest that gene-occupation interaction might play a certain role in exaggerating lumbar disc degeneration. There is a possibility that subjects who carry mutation alleles 5A of MMP-3 and/or A of VDR-Apa are more vulnerable to lumbar disc degeneration when they are exposed to whole-body vibration and/or bending/twisting under ergonomic loads.