Cancer risk of arc welders exposed to fumes containing chromium and nickel

A retrospective follow-up study among chromium- and nickel-exposed welders, which took into consideration welding procedures, duration of exposure, and smoking habits, yielded an increased cancer risk in a comparison with an internal reference group of turners, milling cutters, and drillers, as well as in a comparison with the general population of the Federal Republic of Germany. Due to the cohort size (1 224 welders, 1 694 turners) and the fact that the observation period is still too short, confirmed statements as to the target cancer sites cannot yet be made. However, it emerges that welding with coated electrodes shows a higher cancer risk as compared to the other welding processes observed. This finding may be explained by the fact that the share of hexavalent chromium compounds in the welding fumes is greater with coated electrodes than with other processes so that a follow-up study observing the health risks of chromium and nickel fumes separately would be warranted. For the confirmation of a more favorable outcome with gas-shielded welding, a larger investigation group or a longer observation period would be required.     

Lack of renal changes in stainless steel welders exposed to chromium and nickel.

Biochemical markers of kidney damage were examined in 52 male stainless steel welders (manual metal arc welding) exposed to chromium and nickel. No difference was found in the mean urinary excretion of total proteins, albumin, protein 1, transferrin, retinol-binding protein, lactate dehydrogenase, lysozyme, or beta-N-acetylglucosaminidase in a comparison with matched referents. Beta 2-microglobulin was slightly increased in those welders with a urinary chromium concentration of greater than 64.5 nmol.mmol-1 creatinine. The prevalences of abnormal values did not differ from those observed in the reference group. No correlation was found between the concentrations of chromium or nickel in urine and that of proteins or enzymes. No consistent or clinically significant renal impairment was revealed among the stainless steel welders exposed to a chromium air concentration slightly above the current threshold limit value of the American Conference of Governmental Industrial Hygienists for water-soluble hexavalent chromium compounds (50 micrograms.m-3).     

Sister chromatid exchange analysis in lymphocytes of workers exposed to hexavalent chromium

To investigate the usefulness of sister chromatid exchange (SCE) analysis in lymphocytes as an indicator for mutagenic effects after in vivo exposure to hexavalent chromium (Cr), SCE frequency was analysed in lymphocytes of 44 Cr platers occupationally exposed to hexavalent Cr and 47 controls. Although urinary Cr analysis confirmed that the Cr platers were exposed to Cr, no effects of the exposure on SCE frequency were found. Smokers, both Cr platers and controls, had a significantly higher SCE frequency than non-smokers. These results suggest that SCE analysis in human lymphocytes is not a good indicator of possible mutagenic effects of exposure to hexavalent Cr.     

Mortality study of two overlapping cohorts of photographic film base manufacturing employees exposed to methylene chloride

The mortality experience of two overlapping cohorts of employees engaged in the manufacture of photographic film support was evaluated to assess the potential chronic health effects of methylene chloride exposure. In the first analysis, we examined causes of death among 1311 men initially employed between 1946 (when the solvent was first used) and 1970; in the second, we updated mortality in a 1964 to 1970 employed cohort of 1013 men. Follow-up was through 1994. The mean exposure among members of the 1946 to 1970 cohort was 39 ppm (8-hour time-weighted average) for 17 years, and the median length of follow-up from first exposure was 34 years. Members of the 1964 to 1970 cohort received an average exposure of 26 ppm for 24 years; median time from first exposure was 35 years. Compared with general population vital statistics, mortality in both cohorts was below expectation for all causes of death, ischemic heart disease, and cancer, including such sites as the lung and liver, which were target organs identified in animal toxicology studies. No statistically significant increases were observed for any cause of death. The combined results of this study and three others in the photographic film and textile fibers industries (approximately 7300 subjects) show that long-term exposure to methylene chloride does not increase the risk of death from any cause including specific diagnoses that have been associated with this widely used solvent.     

Sister chromatid exchange analysis in lymphocytes of workers exposed to hexavalent chromium.

To investigate the usefulness of sister chromatid exchange (SCE) analysis in lymphocytes as an indicator for mutagenic effects after in vivo exposure to hexavalent chromium (Cr), SCE frequency was analysed in lymphocytes of 44 Cr platers occupationally exposed to hexavalent Cr and 47 controls. Although urinary Cr analysis confirmed that the Cr platers were exposed to Cr, no effects of the exposure on SCE frequency were found. Smokers, both Cr platers and controls, had a significantly higher SCE frequency than non-smokers. These results suggest that SCE analysis in human lymphocytes is not a good indicator of possible mutagenic effects of exposure to hexavalent Cr.     

Cancer mortality in a Chinese population exposed to hexavalent chromium in drinking water

BACKGROUND: In 1987, investigators in Liaoning Province, China, reported that mortality rates for all cancer, stomach cancer, and lung cancer in 1970-1978 were higher in villages with hexavalent chromium (Cr+6)-contaminated drinking water than in the general population. The investigators reported rates, but did not report statistical measures of association or precision. METHODS: Using reports and other communications from investigators at the local Jinzhou Health and Anti-Epidemic Station, we obtained data on Cr+6 contamination of groundwater and cancer mortality in 9 study regions near a ferrochromium factory. We estimated: (1) person-years at risk in the study regions, based on census and population growth rate data, (2) mortality counts, based on estimated person-years at risk and previously reported mortality rates, and (3) rate ratios and 95% confidence intervals. RESULTS: The all-cancer mortality rate in the combined 5 study regions with Cr+6-contaminated water was negligibly elevated in comparison with the rate in the 4 combined study regions without contaminated water (rate ratio = 1.13; 95% confidence interval = 0.86-1.46), but was somewhat more elevated in comparison with the whole province (1.23; 0.97-1.53). Stomach cancer mortality in the regions with contaminated water was more substantially elevated in comparison with the regions without contaminated water (1.82; 1.11-2.91) and the whole province (1.69; 1.12-2.44). Lung cancer mortality was slightly elevated in comparison with the unexposed study regions (1.15; 0.62-2.07), and more strongly elevated in comparison with the whole province (1.78; 1.03-2.87). Mortality from other cancers combined was not elevated in comparison with either the unexposed study regions (0.86; 0.53-1.36) or the whole province (0.92; 0.58-1.38). CONCLUSIONS: While these data are limited, they are consistent with increased stomach cancer risk in a population exposed to Crz=6 in drinking water.     

Airborne exposure to inhalable hexavalent chromium in welders and other occupations: Estimates from the German MEGA database

This study aimed to estimate occupational exposure to inhalable hexavalent chromium (Cr(VI)) using the exposure database MEGA. The database has been compiling Cr(VI) concentrations and ancillary data about measurements at German workplaces. We analysed 3659 personal measurements of inhalable Cr(VI) collected between 1994 and 2009. Cr(VI) was determined spectrophotometrically at 540 nm after reaction with diphenylcarbazide. We assigned the measurements to pre-defined at-risk occupations using the information provided about the workplaces. Two-thirds of the measurements were below the limit of quantification (LOQ) and multiply imputed according to the distribution above LOQ. The 75th percentile value was 5.2 μg/m³ and the 95th percentile was 57.2 μg/m³. We predicted the geometric mean for 2 h sampling in the year 2000, and the time trend of Cr(VI) exposure in these settings with and without adjustment for the duration of measurements. The largest dataset was available for welding (N = 1898), which could be further detailed according to technique. The geometric means were above 5 μg/m³ in the following situations: spray painting, shielded metal arc welding, and flux-cored arc welding if applied to stainless steel. The geometric means were between 1 μg/m³ and 5 μg/m³ for gas metal arc welding of stainless steel, cutting, hard-chromium plating, metal spraying and in the chemical chromium industry. The exposure profiles described here are useful for epidemiologic and industrial health purposes. Exposure to Cr(VI) varies not only between occupations, but also within occupations as shown for welders. In epidemiologic studies, it would be desirable to collect exposure-specific information in addition to the job title.     

Association of folate deficiency and selected tumor marker concentrations in long-term hexavalent chromium exposed population

Both hexavalent chromium [Cr (VI)] exposure and folate deficiency have been associated with increased cancer risks. Our previous studies have found folate deficiency in Cr (VI) exposed population. Here the relationship between some tumor markers and folate status in long-term Cr (VI) exposure was investigated carefully to show the multiple aspects of Cr (VI) carcinogenesis. A group of 115 workers occupationally exposed to chromate and 60 matched, unexposed controls in Shandong province of China were recruited. Environmental and biological exposure assessments including personal exposure to airborne Cr and Cr contents in erythrocytes were performed. Serum folate, plasma total homocysteine (tHcy) and plasma carcinoembryonic antigen (CEA), neuron specific enolase (NSE), squamous cell carcinoma antigen (SCC), cytokeratin fragment antigen 21-1 (CYFRA 21-1), cancer antigen 72-4 (CA72-4), as well as α-fetoprotein (AFP) were measured. Smoking index (SI) was also calculated to discriminate possible confounding effects of smoking status. Serum folate level decreased significantly, while plasma tHcy, CEA, NSE, SCC, CYFRA21-1, CA72-4 and AFP concentrations increased significantly after Cr (VI) exposure. Meanwhile, plasma CEA, NSE and SCC were negatively correlated with serum folate. SI was negatively correlated with serum folate but positively correlated with plasma tHcy, CEA and NSE levels. Present study suggests that folate deficiency was associated with increased cancer risks and might be affected by smoking in Cr (VI) exposed population. Folate might play a key role in Cr (VI) carcinogenesis although further detailed investigations are needed to clarify the mechanism of this process.     

Evaluating chromosomal damage in workers exposed to hexavalent chromium and the modulating role of polymorphisms of DNA repair genes

Purpose

Welders have been chronically exposed to hexavalent chromium with potential consequences on chromosomal integrity. Our study is focused on the extent of any such chromosomal aberrations with respect to chromium levels in the blood of welders as well as on the tentative modulating role of polymorphisms in DNA repair genes XPD Lys751Gln, XPG Asn114His, XPC Lys939Gln, hOGG1 Ser326Cys and XRCC1 Arg399Gln on chromosomal damage.

Methods

The study was conducted on 144 individuals consisting of 73 welders exposed to chromium for 10.2?±?1.67?years and 71 control individuals without known exposures. Chromosomal aberrations, their chromatid-type and chromosome-type aberrations were detected by conventional cytogenetic analysis. XPD, XPG, XPC, hOGG1 and XRCC1 gene polymorphisms were assayed for by Taqman SNP genotyping assay (“Assay-by-Demand”) using Real-Time allelic discrimination on AB 7500 equipment. Chromium concentration in the blood was determined by atomic absorption spectrophotometry.

Results

The level of chromium in the blood of welders ranged between 0.032 and 0.182?μmol?l^?1 and was significantly higher than that in controls (0.07?±?0.04?μmol?l^?1 vs. 0.03?±?0.007?μmol?l^?1). Parameters of chromosomal damage were similar in both the exposed and the control individuals (1.89% vs. 1.70% for total chromosomal aberrations, 0.97% vs. 0.88% for chromosome-type and 0.92% vs. 0.80% for chromatid-type, respectively). Chromatid-type of aberrations positively correlated with the level of chromium in the blood (r?=?0.28; P?=?0.02). Significantly higher total chromosomal aberrations were detected in individuals with homozygous variant polymorphism in XRCC1 Arg399Gln gene as compared to those with heterozygous and homozygous wild-type genotypes (2.20, 1.89 and 1.48%, respectively; P?=?0.01). A similar tendency was found for chromatid-type aberrations (1.30% for homozygous variant genotype bearers, 0.94% for those with heterozygous genotype and 0.75% for carriers of homozygous wild-type genotype, respectively; P?=?0.04).

Conclusions

Although no apparent increase in chromosomal damage was recorded in chromium-exposed welders in comparison with controls, genetic make-up in DNA repair genes may increase susceptibility toward adverse effect of chromium.     

Study of two cohorts of workers exposed to methyl methacrylate in acrylic sheet production

OBJECTIVES—To study mortality among 4324 workers at two United Kingdom factories, Darwen, Lancashire and Wilton, Cleveland, producing polymethyl methacrylate (PMMA) sheet. The Darwen factory is still active, but the Wilton one was closed in 1970. Also, to investigate patterns of mortality after exposure to methyl methacrylate; in particular, mortality from colon and rectal cancer.
METHODS—All male employees at the Darwen factory with a record of employment in 1949-88 and all men ever employed at the Wilton factory (1949-70) were investigated. The vital status of both cohorts was ascertained on 31 December 1995. The exposure of 1526 subjects at the Darwen plant who were engaged from 1949 onwards could be characterised. The mean duration of exposure was 7.6 years at 13.2 ppm (8 hour time weighted average), although exposures in some work groups were as high as 100 ppm. It was not possible to calculate the cumulative exposure of workers first employed at the Darwen plant before 1949 or workers at the Wilton factory.
RESULTS—In the Darwen cohort, 622 deaths were identified and a further 700 deaths in the Wilton cohort. Mortalities for the cohort were compared with national and local rates and expressed as standardised mortality ratios (SMRs). In the subcohort of Darwen workers with more than minimal exposure to MMA, reduced mortalities compared with national and local rates, were found for all causes (SMR 94), and colorectal cancer (SMR 92), but mortality from all cancers was slightly increased (SMR 104). No relations were found with cumulative exposure to MMA. In the subcohort of Wilton workers, mortality from all causes of death was significantly reduced (SMR 89), but mortality from all cancers (SMR 103) and colorectal cancer (SMR 124) were increased. The excess of colorectal cancer was confined to employees with less than 1 year of employment.
CONCLUSION—The study provided no clear evidence that employment at the factories or exposure to MMA had adversely affected the mortalities of workers.


Keywords: methyl methacrylate; mortality     

接触锰烟尘电焊作业工人对噪声的易感性

对某机械制造企业72名接触噪声作业人员进行纯音听力测试,其中接触锰烟尘的20名电焊工为锰接触组,其余52名机加工为对照组;再根据噪声作业时间分为≤15年、15年两个工龄段,比较分析全部作业人员左耳与右耳、不同工龄段0.5~6 k Hz 6个频率纯音气导听阈变化规律。结果显示,≤15年、15年两个工龄段的两组作业人员的噪声暴露水平差异均无统计学意义(t=23.61、P=0.54,t=24.45、P=0.98);15年工龄段6个频率的听力损失耳检出率均比≤15年工龄段高,其中2、3、4、6 k Hz两两比较差异有统计学意义(P0.05);作业人员在≤15年以及15年两个工龄段中,锰接触组的0.5、1、3、4、6 k Hz频率听力损失耳检出率均比对照组高,并且在3、4、6 k Hz两两比较差异有统计学意义(P0.05);在15年工龄段中,锰接触组1、2、3、4、6 k Hz频段听阈值的中位数较对照组有升高的现象。提示接触锰烟尘的电焊作业人员对噪声有易感性,并随着工龄的延长听力损失有加重趋势。     

Semen quality in welders exposed to radiant heat.

Several studies suggest that welding is detrimental to the male reproductive system. Welding fume and radiant heat are of interest as possible causal factors. This study investigates semen quality and sex hormone concentrations among 17 manual metal arc alloyed steel welders with a moderate exposure to radiant heat (globe temperature ranging from 31.1 degrees to 44.8 degrees C), but without substantial exposure to welding fume toxicants. During exposure to heat the skin temperature in the groin increased on average by 1.4 degrees C (SE +/- 0.72 degrees C). Sperm count and motile sperm count were non-significantly reduced among welders in comparison with two different reference groups. Within the group of welders the proportion of sperm with normal shape declined significantly after six weeks of exposure to heat and increased after a break in exposure. Sperm count and sperm concentration had the same pattern of intraindividual change in relation to exposure to radiant heat, but the changes were not statistically significant. No consistent changes in concentrations of sex hormones were found. The welders investigated were more exposed to radiant heat than welders in general. The results suggest that the study group of welders experienced a reversible decrease in semen quality, most likely caused by a moderate exposure to radiant heat (about five hours a day through several weeks). It remains to be established if even lower levels of exposure to radiant heat in the general population of welders has any impact on semen quality and fertility.     

The use of a multistage model in the analysis of the occupational risks in those exposed to hexavalent chromium

A brief presentation is made of the theory underlying the multistage model of Armitage and Doll and its implications in assessing the effect of exposure to a carcinogen. The theory foresees different relationships between cancer risk and the dependent time variables (time from beginning of exposure, age at start of employment, duration of exposure and time since end of exposure) according to whether the carcinogen acts in the early or late stages of the process of cell transformation leading to tumour formation. The trend in risk of death from lung cancer was studied in a cohort of workers exposed to hexavalent chromium followed up between 1948 and 1985. The results, referred to the multistage model, indicate that hexavalent chromium probably acts in the later stages of the cell transformation process; the implications of this hypothesis for prevention and/or occupational safety strategies are discussed.     

Semen quality in welders exposed to radiant heat.

Several studies suggest that welding is detrimental to the male reproductive system. Welding fume and radiant heat are of interest as possible causal factors. This study investigates semen quality and sex hormone concentrations among 17 manual metal arc alloyed steel welders with a moderate exposure to radiant heat (globe temperature ranging from 31.1 degrees to 44.8 degrees C), but without substantial exposure to welding fume toxicants. During exposure to heat the skin temperature in the groin increased on average by 1.4 degrees C (SE +/- 0.72 degrees C). Sperm count and motile sperm count were non-significantly reduced among welders in comparison with two different reference groups. Within the group of welders the proportion of sperm with normal shape declined significantly after six weeks of exposure to heat and increased after a break in exposure. Sperm count and sperm concentration had the same pattern of intraindividual change in relation to exposure to radiant heat, but the changes were not statistically significant. No consistent changes in concentrations of sex hormones were found. The welders investigated were more exposed to radiant heat than welders in general. The results suggest that the study group of welders experienced a reversible decrease in semen quality, most likely caused by a moderate exposure to radiant heat (about five hours a day through several weeks). It remains to be established if even lower levels of exposure to radiant heat in the general population of welders has any impact on semen quality and fertility.     

A retrospective-cohort study of occupational exposure to hexavalent chromium

A retrospective cohort study was conducted to examine the risk of mortality, cancer, and other adverse health outcomes, at the United States' largest chromate chemicals manufacturing facility in Castle Hayne, North Carolina. This facility, built in 1971, was designed to reduce the high levels of chromium exposure found at most older facilities. Exposure assessment was based on analysis of more than 5,000 personal breathing zone samples collected over a 15-year period. A questionnaire was used to collect relevant occupational, medical, smoking, and other information from current and former employees. Analysis of the cohort's mortality experience found no substantial departures from that expected based on external comparisons, although evidence of a healthy worker effect was observed. Internal cohort analyses were limited by relatively small numbers; however, a subgroup of employees who transferred from older facilities was found to have higher risks of mortality (odds ratio = 1.27 for each 3 years of previous exposure; 90% confidence interval (CI) = 1.07–1.51) and cancer (odds ratio = 1.22 for each 3 years of previous exposure; 90% CI = 1.03–1.45). While this subgroup represented only 11% of the individuals in this study, they accounted for 46% (6/13) of all observed cancers (excluding skin cancers) and 60% (3/5) of lung cancers. There was no increased risk of mortality or cancer among employees who worked only at the newer facility. As an etiologic research study, the results are limited by the relatively small number of subjects and short follow-up; nevertheless, the findings can be used to design and implement a prospective surveillance system for monitoring the health of chromate production workers. © 1994 Wiley-Liss, Inc.     

Decreased serum ceruloplasmin concentration in aluminum welders exposed to ozone

Summary During an epidemiological survey on arc welders, serum copper and ceruloplasmin were determined in two groups of workers. One group consisted of aluminum welders who were divided into two groups: 13 welders working inside aluminum tanks (confined atmosphere) and 8 welders engaged in the production of vans for dump trucks (nonconfined atmosphere). The reference group consisted of 26 workers of the same plant who were not exposed to welding fumes. Ozone, the major pollutant in aluminum arc welding, was thought to be the principal factor in the significant decrease (P < 0.01) of mean ceruloplasmin in confined welders. This decrease in the level of ceruloplasmin was still within the reference values and was not linked to age or to tobacco consumption. We found a linear relationship between ceruloplasmin concentration and the cumulated worktime along the week. This effect could be a sign in the serum of a lung reaction against oxidant activity in this type occupational exposure.