Cohort study among workers exposed to benzene in China: II. Exposure assessment

This report describes a retrospective exposure assessment method used in a follow-up mortality study of workers exposed to benzene. The approach quantified historical exposure to benzene in a multi-industry, multicenter cohort, involving 672 factories in 12 cities in China. Historical exposure data were collected to obtain exposure information related to 1,427 work units (departments) and 3,179 unique job titles from benzene-producing or -using factories in which written records and other data sources were evaluated. The basic unit for exposure assessment was a factory/work unit/job title combination which was considered separately during each of seven calendar-year time periods between 1949 and 1987 for a total of 18,435 exposure assignments. Historical information collected to estimate exposure included benzene monitoring data; lists of raw materials and factory products, and the percentage of benzene in each; the total amount and dates of use of benzene or benzene-containing materials; use of engineering controls and personal protective equipment; and other available exposure information. Overall, 38% (ranging from 3% for the earliest periods to 67% for the last period) of the estimates were based primarily on benzene monitoring data. In the absence of job-specific benzene monitoring data for a given calendar period, measurement results or exposure estimates for similar jobs and/or other calendar periods were used in conjunction with other exposure information to derive estimates. Estimated exposure levels are presented by industries and occupations. The highest average exposures during 1949–1987 were observed for the rubber and plastic industry (30.7 ppm), and for rubber glue applicators (52.6 ppm).     

Occupational epidemiology in the rubber industry: Implications of exposure variability

The variability of exposure has important implications for the design of occupational epidemiologic studies. To assess the influence of this variability in the rubber industry, the efficiency of different schemes for classification of exposure to particulates, cyclohexane-soluble contaminants, and solvents was assessed. Groupings based on job title, plant, factors affecting exposure, published classifications, and the International Standard Classification of Occupations of the International Labor Organization (ISCO-ILO) were compared. Statistical parameters for contrast in average exposure between groups and precision of average exposure within groups were developed to enable comparison of the efficiency of different classification schemes. Grouping of exposure to particulates and dermal exposure appeared to be less efficient than grouping of exposure to solvents. Grouping of solvent exposure using occupational title groups, existing classification schemes, and schemes based on factors affecting exposure showed comparable high resolution in exposure levels. Even the most detailed grouping schemes based on the combination of plant and occupational title group showed relatively modest resolution in particulate and dermal exposure levels. Groupings based on factors affecting exposure showed similar resolution for these exposures, but had higher precision due to having fewer groups. Application of optimal exposure grouping strategies will benefit new research on cancer among rubber workers. Eventually, this might resolve the situation in which a complete industry was included on the list of proven human carcinogens.     

Fertility and exposure to solvents among families in the Agricultural Health Study

Background

Several studies have reported associations between solvent exposure and reduced female fertility, but the evidence is inconclusive for male fertility.

Objectives

To investigate the impact of solvent exposure on subfertility among families of male licensed pesticide applicators in the Agricultural Health Study cohort.

Methods

The couples enrolled between 1993 and 1997. Cross‐sectional questionnaire information on work tasks was used to assess exposure to solvents. The data were limited to couples (wife aged less than 40 years) with an attempt at pregnancy in the last four years (n = 2112).

Results

Twenty eight per cent of the couples were defined as subfertile (not conceiving a pregnancy after at least 12 months of unprotected intercourse, regardless of whether or not a pregnancy ultimately occurred). Adjusted subfertility odds ratios (OR) for exposure to solvents were calculated with logistic regression. Female (OR 1.42, 95% CI 1.15 to 1.75) and male exposure to solvents (OR 1.21 (95% CI 0.93 to 1.57) for monthly exposure and 1.40 (95% CI 0.97 to 2.03) for daily or weekly exposure) were associated with subfertility. In farming, spouses may share or exchange jobs. To account for potential dual exposure, variables for parental exposure (either parent exposed or both parents exposed) were also defined. Both were strongly associated with subfertility (OR 1.62 (95% CI 1.20 to 2.17) and OR 2.10 (95% CI 1.22 to 3.60), respectively).

Conclusions

Solvents may impair fertility of either gender, though the evidence for female effects is stronger than for male effects.     

Polybrominated diphenyl ethers (flame retardants) in mother-infant pairs in the Southeastern U.S.

Polybrominated diphenyl ethers (PBDEs) are commonly used flame retardants in foams, building material, electronics, and textiles. These chemicals leach into the environment, where they persist, and are found today in virtually every population worldwide. Several studies in recent years have detected the presence of PBDEs in maternal and infant samples. However, few of these studies were conducted in the U.S., and few examined paired or matched mother blood-cord blood samples. We analyzed serum from 10 mother-infant pairs for the presence of PBDEs in a patient population in the Southeastern U.S. Out of 35 measured PBDE congeners, five (BDE-28, -47, -99, -100, and -153) were present, with detection frequencies of 65–100 %. The total PBDE concentrations in maternal and infant sera were highly correlated (r² = 0.710, p = 0.0043). The levels of BDE-47, -99, and -100 and of total PBDEs were higher in the infant cord sera when compared with those in maternal sera (p < 0.017), suggesting that fetuses and neonates might have higher circulating concentrations of these potentially neurotoxic and endocrine disrupting chemicals compared with their mothers. The primary focus henceforward should be whether there are any deleterious effects from exposure to these chemicals on human health.     

Different acute effects of single-axis and multi-axis hand-arm vibration

Under laboratory conditions the effects of single-axis and multi-axis hand-arm vibration exposure on several strain parameters were tested in up to 20 male subjects. As parameters of these acute effects, the biodynamic vibration behavior of the hand-arm system, the electrical activity of the most affected muscle groups, the skin temperature, the vibration sensitivity of the fingertips, and the subjective vibration sensation were measured. When comparing simulated three-axis vibration exposure with single-axis vibration exposure, synergistic effects in the form of an increasing reaction could be found. It could be proven that the vector sum of the frequency-weighted acceleration in the three axes represents the acute effects better than does the weighted acceleration in the main axis alone. This summation has to take into account the relatively lower effects of vibration in the x- or y-direction compared with the z-direction. On the basis of the experimental results a new proposal for frequency weighting of the three different axes and an energetic summation procedure are derived. Application of this knowledge in the International Standard ISO 5349 is proposed.     

简易气体动式染毒装置的研制与应用

目的:根据实验需求,研制一种简易气体动式染毒装置.方法:染毒装置由水箱、配气箱、染毒盒和排气瓶4个部分组成.使用有机玻璃板制作箱体,利用排水法精确配气,利用重力作用和调节阀调节气流大小.结果:该装置设计简单合理,经实际使用,染毒效果良好.结论:该简易气体动式染毒装置成本低廉、制作简单、配气精确,可以重复使用,能够满足动式染毒实验需求.     

Cognitive effects of chronic exposure to lead and solvents

BACKGROUND: Occupational exposure to lead and solvents has declined steadily over the past 20 years, however, construction workers continue to be exposed to these neurotoxicants. The purpose of this study was to investigate the cognitive effects of chronic occupational exposure to lead and solvents. METHOD: Based on K-XRF of tibial bone lead and occupational history of solvent exposure, subjects were classified into four exposure groups: lead (N = 40), solvent (N = 39), lead/solvent (N = 45), and control (N = 33). All subjects completed tests to assess concentration, motor skills, memory, and mood. RESULTS: Relative to controls, the lead, solvent, and lead/solvent groups performed significantly more poorly on a test of verbal memory, while the lead and lead/solvent groups were slower than the solvent and control groups on a task of processing speed. Bone lead was a significant predictor of information processing speed and latency of response while solvent exposure was a significant predictor of verbal learning and memory. CONCLUSIONS: Bone lead was associated with slower speed of processing while exposure to lead and/or solvents reduced efficiency of verbal learning.     

Exposure of children to lead and cadmium from a mining area of Brazil

During the past 50 years the Ribeira river valley, in the southern part of the state of S?o Paulo, Brazil, had been under the influence of the full activity of a huge lead refinery and mine working by the side of the river. The plant completely stopped all kinds of industrial activities at the end of 1995, and part of the worker population and their families still remain living nearby in small communities. The objective of the study was to assess the exposure of children to lead and cadmium in these areas, where residual environmental contamination from the past industrial activity still exists. Blood samples of 295 children aged 7 to 14 years, residing in rural and urban areas around the mine and the refinery, were collected. A questionnaire was given to gather information on food habits, leisure activities, father's past employment, current and former residential places, and other variables. Blood lead and cadmium concentrations were analyzed by graphite furnace atomic absorption spectrometry using Zeeman background correction. Cadmium values obtained in this population were mostly below established quantification limits (0.5 microg/dl). The median of blood lead level (BLL) obtained in children living close to the lead refinery was 11.25 microg/dl, and the median in other mining regions far from the refinery was 4.4 microg/dl. Logistic regression analysis was conducted to examine the independent contribution of selected variables in predicting BLL in these children. The following variables showed significant association with high BLL: residential area close to the lead refinery [odds ratio (OR)=10.38 (95% confidence interval (Cl)=4.86-23.25)], former father's occupational lead exposure [OR=4.07 (95% Cl=1.82-9.24)], and male gender [OR=2.60 (95% Cl=1.24-5.62)].     

Exposure of hairdressers to the main cosmetics used in hairdressing salons in France: A preliminary study

In recent years, more attention has been given to chemical exposure in hairdressers. This increasing interest is largely due to the various respiratory and skin symptoms observed in hairdressers. According to these symptoms, hairdressers are in contact with various sources of exposure. Particularly in France, little information is available to assess professional exposure of hairdressers. In order to gather information to assess exposure in hairdressers, 11 hairdressing salons were visited. All the salons were located in Brest City (France). Preferentially, small hairdressing salons were visited. Observations were performed to obtain salon characteristics and to record workers' practices. Calculations revealed that in the worst-case scenario, dermal professional exposure reaches 14.68 and 13.67 mg/kg/day for hair coloring and highlighting mixtures, respectively. Inhalation exposure represents 14.2 and 18.1 mg/kg/day for hair coloring and highlighting mixtures, respectively. These exposure values represent baseline values for exposure of French hairdressers working in small hairdressing salons.     

Further reduction in lead exposure in women in general populations in Japan in the 1990s, and comparison with levels in east and south-east Asia

Objective: The objective of the study was to elucidate the current level of environmental lead (Pb) exposure of women in general population in Japan, where the use of organic Pb in automobile gasoline was phased out from 1973 to reach a zero level early in the 1980s. Methods: A survey was conducted in 27 sites throughout Japan from 1991 to 1997. Five hundred and eighty-eight non-smoking women from the sites offered 24-h food duplicate, peripheral blood, and spot urine samples. Pb in food duplicates (Pb-F), blood (Pb-B), and urine (Pb-U) were analyzed by inductively-coupled plasma mass spectrometry. The results of Pb-F and Pb-B were compared with observations from a study conducted from 1977 to 1981 on 339 women at the same sites. Log-normal distribution was assumed for the evaluation of the results. Results: Geometric means (GMs) of Pb-F, Pb-B, and Pb-U in the 1991–1997 study were 9.0 μg/day, 20.2 μg/l, and 2.18 μg/g creatinine, respectively. The values for Pb-F and Pb-B were substantially lower than the values (32.8 μg/day for Pb-F and 31.7 μg/l for Pb-B) obtained in the 1977–1981 study, which were already low when compared internationally. Cd-U values in the period from 1991 to 1997 also appeared to be among the lowest in the world. Analysis for time-dependent changes in Pb-U was, however, not possible at the time of this study because no values were available for the period from 1977 to 1981. Conclusions: Substantial reductions from 1977–1981 levels in environmental Pb exposure were observed among the study populations in Japan. Current exposure levels appear to be lower than those in other parts of Asia, the USA, and Europe. Received: 16 March 1999 / Accepted: 27 August 1999     

Applicability of homogeneous exposure groups for exposure assessment in the chemical industry

The purpose of the study was to assess occupational exposure to chemicals, by taking the aspects presented in European standard EN 689 into account, especially with respect to homogeneous exposure groups and their suitability as the basis for exposure assessment. In addition, dermal exposure to chemicals was assessed when appropriate. The industries studied included a plywood factory, a paint factory and a sewage treatment plant of an oil refinery. The workers were classified into homogeneous exposure groups by the persons in charge of occupational health issues in the respective workplaces. The concentrations of the contaminants were measured in workplace air by breathing-zone and stationary sampling, and these approaches were compared. Dermal exposure was measured when applicable. The homogeneity of the grouping was tested with analysis of variance whenever possible. The tasks studied in plywood manufacturing fulfilled the criteria of homogeneous exposure groups for both respiratory and dermal exposure. The group of operators in the sewage treatment plant was highly homogeneous. The complicated organization of the tasks made the use of homogeneous exposure groups (HEG) unsuitable at the paint factory. These findings show that reliable exposure assessment cannot be achieved with a formal standard; instead, comprehensive occupational hygiene evaluation is needed. It should also have a great importance when exposure models are developed. Received: 27 December 1999 / Accepted: 6 May 2000     

Occupational and environmental human lead exposure in Brazil

The purpose of this paper is to present a review of data on assessment of exposure and adverse effects due to environmental and occupational lead exposure in Brazil. Epidemiological investigations on children lead exposure around industrial and mining areas have shown that lead contamination is an actual source of concern. Lead in gasoline has been phasing out since the 1980s, and it is now completely discontinued. The last lead mining and lead refining plant was closed in 1995, leaving residual environmental lead contamination which has recently been investigated using a multidisciplinary approach. Moreover, there are hundreds of small battery recycling plants and secondary smelting facilities all over the country, which produce focal urban areas of lead contamination. Current regulatory limits for workplace lead exposure have shown to be inadequate as safety limits according to a few studies carried out lately.     

Is it feasible to construct a community profile of exposure to industrial air pollution?

OBJECTIVE—An epidemiological investigation to assess the validity of residential proximity to industry as a measure of community exposure.
METHODS—19 Housing estates in Teesside (population 1991: 77 330) in north east England were grouped into zones: A=near; B=intermediate; C=further from industry. With residential proximity of socioeconomically matched populations as a starting point a historical land use survey, historical air quality reports, air quality monitoring, dispersion modelling data, and questionnaire data, were examined.
RESULTS—The populations in zones A, B, and C were similar for socioeconomic indicators and smoking history. Areas currently closest to industry had also been closest for most of the 20th century. Historical reports highlighted the influence of industrial emissions to local air quality, but it was difficult to follow spatial pollution patterns over time. Whereas contemporary NO_x and benzene concentrations showed no geographical variation, dispersion modelling of emissions (116 industrial stacks, traffic, and domestic sources) showed a gradient associated with industry. The presumed exposure gradient of areas by proximity to industry (A>B>C) was evident for all of zone A and most of zones B and C.
CONCLUSIONS—It was feasible to assemble a picture of community exposure by integration of measurements from different sources. Proximity of residence was a reasonable surrogate for complex community exposure.


Keywords: exposure assessment; community exposure; industrial pollution     

Reducing attenuation in exposure-response relationships by exposure modeling and grouping: the relationship between wood dust exposure and lung function

BACKGROUND: In a study of wood dust exposure and lung function, we tested the effect on the exposure-response relationship of six different exposure metrics using the mean measured exposure of each subject versus the mean exposure based on various methods of grouping subjects, including job-based groups and groups based on an empirical model of the determinants of exposure. METHODS: Multiple linear regression was used to examine the association between wood dust concentration and forced expiratory volume in 1s (FEV(1)), adjusting for age, sex, height, race, pediatric asthma, and smoking. RESULTS: Stronger point estimates of the exposure-response relationships were observed when exposures were based on increasing levels of aggregation, allowing the relationships to be found statistically significant in four of the six metrics. The strongest point estimates were found when exposures were based on the determinants of exposure model. CONCLUSIONS: Determinants of exposure modeling offers the potential for improvement in risk estimation equivalent to or beyond that from job-based exposure grouping.     

Toxic trace elements in maternal and cord blood and social determinants in a Bolivian mining city

This study assessed lead, arsenic, and antimony in maternal and cord blood, and associations between maternal concentrations and social determinants in the Bolivian mining city of Oruro using the baseline assessment of the ToxBol/Mine-Niño birth cohort. We recruited 467 pregnant women, collecting venous blood and sociodemographic information as well as placental cord blood at birth. Metallic/semimetallic trace elements were measured using inductively coupled plasma mass spectrometry. Lead medians in maternal and cord blood were significantly correlated (Spearman coefficient = 0.59; p < 0.001; 19.35 and 13.50 μg/L, respectively). Arsenic concentrations were above detection limit (3.30 μg/L) in 17.9 % of maternal and 34.6 % of cord blood samples. They were not associated (Fischer’s p = 0.72). Antimony medians in maternal and cord blood were weakly correlated (Spearman coefficient = 0.15; p < 0.03; 9.00 and 8.62 μg/L, respectively). Higher concentrations of toxic elements in maternal blood were associated with maternal smoking, low educational level, and partner involved in mining.     

Indirect lead exposure among children of radiator repair workers

BACKGROUND: Secondary exposure to lead has been identified as a public health problem since the late 1940s; we investigate the risk of lead exposure among families of radiator repair workers. METHODS: A sample of the wives and children, aged 6 months to 6 years (exposed children) (n = 19), of radiator repair workers and a sample of children whose parents were not occupationally exposed to lead (non-exposed children) (n = 29) were matched for age and residence; their geometric mean blood lead levels are compared. Blood samples were obtained by the finger stick method and environmental dust samples by the wipe method; both were analyzed using a portable anodic stripping voltameter. RESULTS: Dust lead levels were significantly higher in the houses of exposed children (143.8 vs. 3.9 microg/g; P < 0.01). In crude analyses, the highest lead levels were observed among children whose fathers worked in home-based workshops (22.4 microg/dl)(n = 6). Children whose fathers worked in an external workshop (n = 13) also had high levels (14.2 microg/dl) (P < 0.01), while blood lead levels in non-exposed children were significantly lower (5.6 microg/dl)(P < 0.01). The observed differences remained significant after adjustment for age and gender. CONCLUSIONS: This study confirms that children of radiator repair workers are at increased risk of lead exposure and public health interventions are needed to protect them.     

二甲基甲酰胺作业工人皮肤污染量研究

Objective To establish a method for the determination of dimethylformamide(DMF) and investigate dermal contamination and absorption among workers occupationally exposed to DMF. Method 37 workers exposed to DMF were divided randomly into two groups. DMF was washed down by isopropyl alcohol in A group (16 workers) and water in B group(21 workers).Gas chromatography was used for the quantification of dermal contamination and N-methylformamide(NMF) in urine, correlative study was done between them. Results DMF could be detected in all samples in A group, but could not be detected in B group. The miscel-laneous peaks could be completely separated from the DMF peak in the sample spectrum, without matual in-ference. The highest degree of total dermal contamination was observed in wet spinning workshop[(2.84±1.31 ) ing], postprocessing workshop[(2.50±0.95) mg] and dry spinning workshop[( 1.95±0.61) mg] were lower. The respiratory cumulative exposure dosages were 351.3, 201.3 and 135.2 mg respectively. The average DMP concentration in air of the third printing processing workshop, the dry spirning workshop and the wet spinning workshop was 60.2, 89.6, 156.4 mg/m3 respectively, and the respiratory tract contamination in the workers of the three workshops were 135.2, 201.3 and 351.3 mg respectively. There was statistical independence between the quantification of total dermal contamination and NMF in urine (r=0.176,P>0.05). Conclusion Isopropyl alcohol is the effective washing solvent.When the concentration of DMF in workplace air is above the occupa-tional exposure limit, respiratory tract absorption is the principal pathway of DMF absorption,but dermal con-tamination of DMF should not be ignored.     

二异氰酸甲苯酯对工人危害的调查

为保护工人健康于1984年8月对大连市二异氰酸甲苯酯（TDI）生产及使用厂进行了流调，接触组117人，对照组82人，调查结果表明：车间内此种毒物浓度在0．2mg/m^3左右的情况下，接触者可出现损害作用，其表现如下：（1）原发刺激作用表现呼吸道刺激的症状和体征；（2）变态反应（IgE明显增高）；（3）肝大、轻度肝功能异常；（4）神衰症候群，膝反射减弱及脑电图改变；（5）肺活量降低。     

职业接触二硫化碳生物接触限值的探讨

目的 探讨我国职业接触二硫化碳(CS2)的生物接触限值.方法 用高效液相色谱法测定工人班末尿中2-硫代噻唑烷-4-羧酸(TTCA)含量,用气相色谱法测定接触CS2工人作业场所空气中CS2浓度,探讨二者的相关关系,比较生物接触限值和PC-TWA判定结果.结果 CS2作业工人班末尿中TTCA含量与其接触的工作场所空气中CS2浓度呈正相关,回归方程式Y=0.265X-0.165 (r=0.91,P＜0.01).基于本次研究的回归方程,根据GBZ 2.1-2007《工作场所有害因素职业接触限值第1部分:化学有害因素》规定的CS2的PC-TWA 5 mg/m3推算,CS2接触工人班末尿中TTCA浓度生物限值为1.2 mgTTCA/g Cr.结论 建议我国CS2生物接触限值修订为1.2 mg TTCA/g Cr.     

二甲基甲酰胺作业工人皮肤污染量研究

Objective To establish a method for the determination of dimethylformamide(DMF) and investigate dermal contamination and absorption among workers occupationally exposed to DMF. Method 37 workers exposed to DMF were divided randomly into two groups. DMF was washed down by isopropyl alcohol in A group (16 workers) and water in B group(21 workers).Gas chromatography was used for the quantification of dermal contamination and N-methylformamide(NMF) in urine, correlative study was done between them. Results DMF could be detected in all samples in A group, but could not be detected in B group. The miscel-laneous peaks could be completely separated from the DMF peak in the sample spectrum, without matual in-ference. The highest degree of total dermal contamination was observed in wet spinning workshop[(2.84±1.31 ) ing], postprocessing workshop[(2.50±0.95) mg] and dry spinning workshop[( 1.95±0.61) mg] were lower. The respiratory cumulative exposure dosages were 351.3, 201.3 and 135.2 mg respectively. The average DMP concentration in air of the third printing processing workshop, the dry spirning workshop and the wet spinning workshop was 60.2, 89.6, 156.4 mg/m3 respectively, and the respiratory tract contamination in the workers of the three workshops were 135.2, 201.3 and 351.3 mg respectively. There was statistical independence between the quantification of total dermal contamination and NMF in urine (r=0.176,P>0.05). Conclusion Isopropyl alcohol is the effective washing solvent.When the concentration of DMF in workplace air is above the occupa-tional exposure limit, respiratory tract absorption is the principal pathway of DMF absorption,but dermal con-tamination of DMF should not be ignored.