Enteric parasites in workers occupationally exposed to sewage

To determine if parasitic infections occur more frequently among workers exposed to wastewater than among controls, parasitologic examinations were performed on stool specimens collected over a 12-month period from sewer and highway maintenance workers. Three of 56 sewer maintenance workers (5.4%) had at least one positive specimen compared with 10 of 69 highway workers (14.5%). The highest rate was found among highway workers engaged in street cleaning. Contrary to studies conducted outside the United States, the present study does not indicate that parasitic infections occur more frequently among sewer workers than among controls in the urban midwestern United States. The results of this study indicate that there may be a risk of parasitic infections among street cleaners.     

Morbidity and mortality in workers occupationally exposed to pesticides

Utilizing cause-of-death information and responses to questionnaires addressed to survivors, mortalities and health impairments in a cohort of workers occupationally exposed to pesticides were compared to occurrences in workers not pesticide exposed, over the period 1971–1977. Seventy-two percent of 2,620 pesticide-exposed workers, and 75 percent of 1,049 controls, recruited in 1971–73, were accounted for either by returned questionnaire or mortality. Disease incidence rates were studied in relation to broadly defined occupational subclasses, and to serum concentrations of organochlorine pesticides (OC1) measured at the time of recruitment.Death by accidental trauma was unusually frequent among pesticide applicators. Mortalities from cancer and arteriosclerosis were not detectably different from those observed in the controls. Among survivors, dermatitis and skin cancer were unusually common in structural pest-control operators. Internal cancer was no more frequent in the intensively pesticide-exposed workers than in the controls, but it appeared to occur at an unusually high rate in workers characterized as possibly pesticide-exposed.There were apparent associations between high serum pesticide OCl levels measured in 1971–73 and the subsequent appearance of hypertension, arteriosclerotic cardiovascular disease, and possibly diabetes. This could imply a causal role of any of the pesticidal and other environmental stresses to which these workers were exposed.The limitations of this type of followup study are discussed.     

Genotoxicity evaluation in workers occupationally exposed to lead

Lead (Pb) is a widely used heavy metal with a broad industrial usage. Nevertheless, Pb is a serious public health issue as it is one of the most widespread environmental and industrial toxins. The aim of this investigation was to assess the genotoxicity of Pb using the comet assay, micronucleus (MN) and chromosomal aberrations (CA) test. Blood and urinary Pb content, levels of δ-aminolevulinic acid dehydratase in the erythrocytes (E-ALAD) and δ-aminolevulinic acid in urine (U-ALA) were determined. The exposure associated oxidative stress was also studied. The study group comprised of 90 male Pb recovery unit workers and 90 matched controls. The results indicated that the exposed workers had a significantly higher mean comet tail length than that of controls (P<0.05). Analysis of micronuclei in buccal epithelial cells (BEC’s) and peripheral blood lymphocytes (PBL) revealed that there was a significant increase in frequency of MN in exposed subjects than controls. The frequency of aberrant metaphases was also found to be significantly elevated in the Pb exposed workers. The levels of antioxidant enzymes were relatively reduced (P>0.05) while the rate of lipid peroxidation was higher in the exposed subjects. Blood and urinary Pb concentrations were found to be higher in exposed workers than in controls. E-ALAD levels were reduced and U-ALA levels were elevated in the exposed subjects in comparison to controls. Results of analysis, taking the confounding factors into consideration provide evidence for the association of Pb exposure and genotoxicity, and predict the increased risk of cancer to the exposed workers. In view of the observed results, it can be strongly concluded that the workers comprise the risk group and adequate safety, precautionary and preventive measures could only minimize exposure and the related health hazards.     

n-Hexane metabolism in occupationally exposed workers

Lung uptake and excretion of n-hexane were studied in ten workers in a shoe factory. Simultaneous samples of inhaled and alveolar air were collected with the aid of a Rhan-Otis valve, personal samplers, and charcoal tubes. Alveolar excretion was monitored during a six hour postexposure period. Uptake was calculated from lung ventilation, the retention coefficient, and environmental concentrations. The amount of exhaled n-hexane was calculated from the decay curve. According to the experimental data, alveolar retention was about 25% of the inhaled n-hexane, corresponding to a lung uptake of about 17%. The postexposure alveolar excretion was about 10% of the total uptake. The main metabolites of n-hexane were identified and measured by capillary GC/MS in spot urine samples collected before, at the end, and 15 hours after the same working shift. Urinary concentrations were low, though related to n-hexane in the air. 2,5-Hexanedione in the end of shift samples gave the best estimate of overall exposure. About 3 mg/g creatinine of 2,5-hexanedione would correspond to about 50 ppm of n-hexane in the air (mean daily exposure).     

长春新碱作业工人的遗传效应

目的研究长春新碱作业工人的遗传效应。方法用微核试验、彗星试验、hprt基因突变试验和TCR基因突变试验对15名长春新碱接触工人和15名对照组工人外周血淋巴细胞进行检测。结果接触组平均微核率(MNR)、平均微核细胞率(MCR)分别为1．78%±0．19%和1．37%±0．16%,对照组分别为0．37%±0．08%和0．31%±0．06%,差异有统计学意义(P＜0．01)。接触组和对照组的平均尾长(MTL)分别为(1．72±0．15)μm和(0．71±0．01),μm,差异有统计学意义(P＜0．01)。两组平均尾相(MTM)分别为0．29±0．03和0．17±0．05,差异无统计学意义(P＞0．05)。接触组和对照组的hprt平均突变率分别为0．10%±0．002%和0．09%±0．001%,差异有统计学意义(P＜0．05)。接触组和对照组的TCR平均突变率分别为(2．52±0．34)×10~(-4)和(1．51±0．11)×10~(-4),差异亦有统计学意义(P＜0,01)。结论长春新碱作业工人已出现明显的遗传效应。     

铝熔铸作业工人神经行为功能的研究

为探讨铝对作业工人神经系统的影响，寻找对铝作业工人健康监护的早期指标，对３６名铝熔铸作业工人（车间空气中铝尘和铝浓度分别为１．６５ｍｇ／ｍ３和０．２５ｍｇ／ｍ３（ＴＷＡ））和４０名对照工人，应用ＷＨＯ－ＮＣＴＢ进行了神经行为功能测定；同时测定了尿铝、尿中高香草酸（ＨＶＡ）和香草扁桃酸（ＶＭＡ）的含量。结果发现：铝接触工人注意力、手的运动协调能力、视感知记忆力下降，反应时的标准差和最慢反应时间延长（Ｐ＝０．００２５，Ｐ＝０．００６６），提转捷度测试得分降低（Ｐ＝０．０２６），数字译码和Ｂｅｎ－ｔｏｎ视觉保留测试得分降低（Ｐ＝０．０２３，Ｐ＝０．００３）。分层分析发现：后３项分测试得分随接触时间延长而降低，铝作业工人尿ＶＭＡ和尿铝含量高于对照组。提示：铝可能对作业工人的神经系统产生影响。神经行为测试和尿ＶＭＡ测定可用于检测铝的不良效应     

Immunological changes among workers occupationally exposed to styrene

The functional status of the immune system was investigated in a group of 71 workers exposed to styrene and in 65 control subjects, recruited according to the same selection criteria and comparable as to sex, age, and confounding variables. Air and biological monitoring were used to characterize styrene exposure (median of the main urinary metabolites in the next-morning spot samples: 106 mg/g creatinine). Phenotypic analysis of peripheral blood lymphocytes (PBL) by automated flow cytometry revealed a reduced proportion of T lymphocyte subsets (CD3⁺, CD4⁺ and CD4⁺45⁺), with no changes in CD8⁺, and a higher proportion of B lymphocytes (CD19⁺) among styrene-exposed workers. The exposed workers showed a higher proportion of activation markers, namely DR and interleukin-2 receptors (CD25). Immunoglobulin subclasses were comparable in the two groups. An increased prevalence of abnormally low values was apparent for CD2⁺, CD3⁺, CD4⁺, CD4⁺45⁺ and CD11b subsets among workers exposed to styrene, whereas CD19⁺, DR⁺ and CD25⁺ showed an increased prevalence of abnormally high values. Natural killer-related phenotypes (CD56⁺, CD56+16⁺, and CD56⁺16^–) were more expressed among styrene workers, with average increase of 30%. However, the frequency distribution of the lytic activity of natural killer cells against K-562 target cells was shifted towards lower values in the exposed workers as compared to control subjects. Dose-response relationships between indices of internal dose and prevalence of abnormal values were detectable for T lymphocyte subsets, NK phenotypes, and activation markers. These findings suggest that moderate exposure to styrene is associated with an altered distribution of lymphocyte subsets. The decreased proportion of T lymphocytes, mainly of T helper-inducer cells, could hamper regulatory functions, thus suggesting a negative modulation by styrene exposure. Since a proper balance between immunocycte subsets is important for immunological responses, such changes should be regarded as adverse effects.     

Lymphocyte subpopulations in workers exposed occupationally to styrene]

In a group of 32 workers occupationally exposed to styrene, the distribution of lymphocyte subsets was investigated by automated flow cytometry. The group under study consisted of 22 male and 10 female workers aged 39.7, D.S. = 10 years and employed for 6.8 years in factories manufacturing glass fibre-reinforced plastics. A control group (12 males and 7 females) recruited according to the same selection criteria was simultaneously examined. Environmental and biological monitoring was used to characterize styrene exposure. In styrene-exposed workers, phenotypic analysis of peripheral blood revealed a reduced proportion of T helper lymphocytes and a relative increase in the T suppressor subset, leading to a significant inversion of the helper/suppressor ratio (0.92) among heavily exposed workers (greater than 50 ppm, 8h-TWA) as compared to less exposed workers and controls (1.37 and 1.43 respectively). The proportion of natural killer (NK) T lymphocytes was significantly increased among styrene workers. The proportion of B lymphocytes was unchanged as compared to the control group. Dose-response relationships were clearly apparent for the observed increases in the prevalence of abnormalities: none of control subjects showed more than 2 (out of 8) abnormal values as compared to 20 and 40% of styrene workers belonging respectively to the low and high exposure group (p less than 0.007). Only a minority of controls exhibited abnormally high levels of both NK and suppressor T lymphocytes (0-5%), the corresponding figures for styrene workers being 7-10% (low exposure) and 45% (high exposure). As a whole, the findings support the hypothesis of the immunotoxicity of styrene, which could be due either to direct effects on lymphocytes or to indirect mechanisms possibly mediated by neuroendocrine changes.     

铅作业工人SCL-90调查分析

目的探讨铅作业工人心理健康状况及其影响因素。方法对89名铅作业工人进行SCL-90量表评定,并与正常人群进行比较。结果铅作业工人SCL-90总分、阳性项目数、6个因子得分均显著高于对照组。躯体化症状阳性检出率25.8%,抑郁症状阳性检出率12.3%,偏执症状阳性检出率11.2%,敌对症状阳性检出率10.1%,恐怖症状阳性检出率8.9%。不同经济类型工厂、尿铅浓度、血锌原卟啉浓度与躯体化、抑郁、偏执、敌对、恐怖、人际关系敏感阳性症状检出率存在相关。结论职业性铅接触可影响工人的精神心理卫生,不同经济类型工厂对精神卫生影响不同。     

n-Hexane metabolism in occupationally exposed workers.

Lung uptake and excretion of n-hexane were studied in ten workers in a shoe factory. Simultaneous samples of inhaled and alveolar air were collected with the aid of a Rhan-Otis valve, personal samplers, and charcoal tubes. Alveolar excretion was monitored during a six hour postexposure period. Uptake was calculated from lung ventilation, the retention coefficient, and environmental concentrations. The amount of exhaled n-hexane was calculated from the decay curve. According to the experimental data, alveolar retention was about 25% of the inhaled n-hexane, corresponding to a lung uptake of about 17%. The postexposure alveolar excretion was about 10% of the total uptake. The main metabolites of n-hexane were identified and measured by capillary GC/MS in spot urine samples collected before, at the end, and 15 hours after the same working shift. Urinary concentrations were low, though related to n-hexane in the air. 2,5-Hexanedione in the end of shift samples gave the best estimate of overall exposure. About 3 mg/g creatinine of 2,5-hexanedione would correspond to about 50 ppm of n-hexane in the air (mean daily exposure).     

Semen quality of industrial workers occupationally exposed to chromium

A total of sixty-one subjects occupationally exposed to chromium in an industry which manufactures chromium sulphate and fifteen control subjects from a nearby industry which does not manufacture any chromium related compounds were studied. The history of each subject was recorded on pre-designed form through interview and a routine medical examination was carried out. Blood samples (5-6 ml) were collected for the estimation of chromium and semen samples were collected for semen analysis and the determination of copper and zinc levels in the seminal plasma. Clinical examination revealed nasal perforation in 10 subjects (out of 61) in the exposed group as compared to none in the control group. A significantly higher level of chromium was observed in the blood of the exposed workers as compared to the control. The concentration of zinc in seminal plasma was lower while the level of copper was higher in the exposed group as compared to the control. However, these changes were not statistically significant. Statistically significant higher numbers of morphologically abnormal sperms were noticed in the exposed group with respect to the control. Further analysis of the data indicated that about 53% of the exposed subjects showed less than 30% normal forms as compared to 10% in control subjects. However, no significant alterations in semen volume, liquefaction time, mean pH value, sperm viability, concentration or motility, were noticed between chromium exposed and unexposed workers. The data also indicates that exposure to chromium has some effect on human sperm as a significant positive correlation (r=0.301) was observed between percentages of abnormal sperm morphology and blood chromium levels (p=0.016) after pooling all the data of the control and exposure groups.     

职业砷接触工人某些遗传毒性指标的变化

目的探讨职业砷接触工人某些遗传毒性指标的变化。方法选择云南某砒霜厂40人为接触组,当地无明显毒物接触史28人为对照组,检测并评价外周血淋巴细胞微核细胞率、微核率、彗星试验拖尾率和尾长,以及尿中总砷、有机砷水平。结果接触组外周血淋巴细胞微核细胞率、微核率、彗星试验拖尾率、尾长均极显著高于对照组(P<0.01)。尿中总砷、有机砷浓度也高于对照组(均低于0.02mg/L)。微核细胞率和微核率随有机砷浓度、工龄乘积增加有升高趋势(rs=0.356,P=0.024;rs=0.347,P=0.028)。结论职业性砷暴露可导致外周血淋巴细胞染色体和DNA损伤。     

Alteration of thiol-disulfide homeostasis in workers occupationally exposed to arsenic

This study evaluates the redox state in occupationally arsenic-exposed workers (n = 71) by assessing the dynamic serum thiol-disulfide homeostasis. We determined the serum thiol-disulfide homeostasis parameters of exposed workers and controls (n = 43) using a novel automated colorimetric assay. Median urinary As and 8-isoprostane levels of exposed group were significantly higher than control group (16.40 μg/L vs 2μg/L, p < .001 and 2.28 ng/ml vs 0.54 ng/ml, p < .001, respectively). Disulfide level, disulfide/native thiol ratio, and disulfide/total thiol ratio were significantly higher in exposed group. The mean ceruloplasmine and myeloperoxidase activities of As-exposed group were significantly higher than control group (117.15 U/L vs 87.02 U/L, p = .035 and 148.53 U/L vs 97.75 U/L, p = .000, respectively). The median catalase activity did not differ in the two groups. Our findings revealed that As disrupts the thiol-disulfide homeostasis in favor of disulfide.     

Respiratory health of plywood workers occupationally exposed to formaldehyde

This study was undertaken to enlarge our understanding of the adverse health effects of formaldehyde exposure in the workplace and community environment. The respiratory health status of 186 male plywood workers was evaluated by spirometric tests, respiratory questionnaires, and chest x-rays. Area concentrations of formaldehyde were measured in the work environment and found to range from 0.28 to 3.48 ppm. The average personal exposure was to 1.13 ppm of formaldehyde. Exposure to formaldehyde was associated with decrements in the baseline spirometric values, i.e., forced expiratory volume in 1 sec (FEV1.0), forced expiratory volume/forced vital capacity (FEV/FVC), and FEF25%-75%, and with several respiratory symptoms and diseases, including cough, phlegm, asthma, chronic bronchitis, and chest colds. The results of the study support the hypothesis that chronic exposure to formaldehyde induces symptoms and signs of chronic obstructive lung disease.