Respiratory health of automobile workers exposed to metal-working fluid aerosols: Respiratory symptoms

A total of 1,811 automobile workers at three General Motors facilities were evaluated by questionnaire for possible respiratory effects resulting from airborne exposures to metal-working fluids (MWF): 1,042 currently worked as machinists and were exposed to one of three types of MWF aerosols (straight mineral oils, soluble oil emulsions, or water-based synthetic fluids that contained no oils); 769 assembly workers, without direct exposure, served as an internal reference group (of these, 239 had never worked as machinists). Symptoms of usual cough, usual phlegm, wheezing, chest tightness, and breathlessness, as well as physician-diagnosed asthma, and chronic bronchitis were the primary outcomes examined. Machinists as a whole had higher prevalence of cough, phlegm, wheezing, and breathlessness than that of assembly workers. Adjusting for confounding, phlegm and wheeze were associated with increasing levels of current exposure to straight oils; cough, phlegm, wheeze, chest tightness, and chronic bronchitis were associated with increasing levels of current exposure to synthetics. In models that included both past and current exposure, only current exposures to straight and synthetic fluids were associated with current symptoms. Am. J. Ind. Med. 32:450–459, 1997. © 1997 Wiley-Liss, Inc.     

Occupational exposure to metalworking fluids and risk of breast cancer among female autoworkers

BACKGROUND: Metalworking fluids (MWF) are used for lubrication during metal manufacturing. Previous studies have observed increased risks of several cancers among MWF-exposed workers. We hypothesized that MWF may be associated with risk of breast cancer because they can contain carcinogenic or endocrine-disrupting chemicals. METHODS: We conducted a case-control study nested in a cohort of 4,680 female automobile workers employed for at least 3 years between 1/1/41 and 1/1/85, with follow-up through 1994. Cases were identified using the National Death Index (NDI), Michigan cancer registries, and company records. Detailed quantitative MWF exposure data were available for each subject, although data on known breast cancer risk factors were not. RESULTS: Ninety-nine cases of breast cancer and 626 matched controls were identified. There was a weak positive association between lifetime cumulative exposure to soluble MWF and breast cancer risk, but no evidence of association with either straight or synthetic fluids. When exposure was divided into time-windows, the association was strongest for soluble MWF in the decade preceding diagnosis. Controlling for earlier exposures, there was an odds ratio of 1.18 (95% CI=1.02-1.35) per mg/m3-year of cumulative exposure to soluble MWF in this 10-year period. CONCLUSION: This hypothesis-generating study provides some preliminary evidence for an association between exposure to soluble MWF and increased risk of breast cancer. Additional studies of MWF and breast cancer, with data on known breast cancer risk factors, are warranted.     

Mortality studies of machining-fluid exposure in the automobile industry. II. Risks associated with specific fluid types.

Excesses of digestive and respiratory cancers have been reported previously in association with exposure to machining fluids, agents in widespread use as coolants and lubricants in machining operations. Previous studies have had limited power to distinguish the effects of the different types of machining fluids in use. In a cohort of over 30,000 workers employed at two automotive plants in Michigan, mortality patterns were studied in relation to exposure to each of the three major fluid types--straight oils, soluble oils, and synthetic fluids. Standardized mortality ratios were estimated for subgroups of the cohort ever exposed to each of the three fluid types, and Poisson regression analyses were used to assess trends in risk with duration of exposure. The data suggest modest positive associations between exposure to straight oils and rectal, laryngeal, and prostatic cancer and a negative association between soluble and synthetic fluid exposure and lung cancer.     

Mortality studies of metalworking fluid exposure in the automobile industry: VI. A case-control study of esophageal cancer

Background Results are reported from a nested case-control study of 60 esophageal cancer deaths among 46,384 automobile manufacturing workers potentially exposed to metalworking fluids (MWF) in machining and grinding operations. Methods By using incidence-density sampling, controls were selected with a sampling ratio of 20:1 from among co-workers who remained at risk by the age of death of the case, matched on race, gender, plant, and year of birth. Conditional logistic regression was used to evaluate the risk associated with cumulative exposure (mg/m³-years) to each of three types of metalworking fluid (straight, soluble, and synthetic MWF), as well as with years of exposure to selected components of MWF, including nitrosamines, sulfur, biocides, and several metals. Results Esophageal cancer was found to be significantly associated with exposure to both soluble and synthetic MWF in grinding operations. The odds ratios (ORs) for grinding with soluble MWF were elevated at 2.5 or greater in all categories of cumulative exposure, although the exposure-response trend was statistically significant only when exposure was measured as duration. Those with 12 or more years exposure to soluble MWF in grinding operations experienced a 9.3-fold relative risk of esophageal cancer mortality (95% CI = 2.1–42.1). The OR for ever grinding with synthetic MWF was 4.1 (95% CI = 1.1–15.0). Elevated risk was also associated with two agents found in both synthetic and soluble fluids, nitrosamines, and biocides. For exposure to nitrosamines, the OR was 5.4 (95% CI = 1.5–19.9); for biocides the OR was 3.8 (95% CI = 0.8–18.9). However, because the same workers were exposed to grinding with synthetics, nitrosamines and biocides, it was not possible to separate the specific risks associated with these components. Am. J. Ind. Med. 34:36–48, 1998. © 1998 Wiley-Liss, Inc.     

Exposure-response models based on extended follow-up of a cohort mortality study in the automobile industry

OBJECTIVE: This report describes the extended follow-up of a cohort of 46 399 automobile manufacturing workers with potential exposure to metalworking fluids (MWF). The outcomes of interest were cancers of the esophagus, stomach, colon, rectum, liver, pancreas, larynx, skin, prostate, and brain, as well as leukemia. Additional follow-up increased the power to detect modest elevations in mortality rates in association with specific types of MWF, including synthetic fluids not in widespread use until the 1970s. METHODS: Standardized mortality ratios (SMR) were computed for the most recent 10 years of follow-up, as well as for the entire study period. Adjusted relative risks (RR) were estimated in Poisson regression models with categorical variables for cumulative exposure to each type of MWF and in proportional hazards models with continuous exposure variables. RESULTS: Associations were found between straight MWF and esophageal, laryngeal and rectal cancer; soluble MWF and cancer of the esophagus, larynx, skin, and brain; synthetic MWF and cancer of the esophagus, liver, and prostate. The elevated RR values were modest in magnitude (1.5 to 2.0). SMR values were increased for stomach, liver, and pancreatic cancer and also for leukemia in the last 10 years of follow-up. The SMR values were also elevated for stomach and liver cancer among the persons recently hired. CONCLUSIONS: The results provide further evidence that exposure to metalworking fluids causes cancer among workers in automobile manufacturing. Although airborne exposures declined over the study period, this study suggests that modest risk of several digestive cancers, as well as prostatic cancer and leukemia, may persist at current levels of exposure to water-based metalworking fluids.     

A nested case-control study of stomach cancer mortality among automobile machinists exposed to metalworking fluid

PURPOSE: In a nested case-control study of 140 stomach cancer deaths (1941-1984) among 46,384 automobile workers, we examined risk in relation to lifetime exposure to metalworking fluid (MWF) in machining and grinding operations.METHODS: Exposure was defined during varying windows of biologic time (<10 years before death, 10-20 years before death, and > 20 years before death) and evaluated using a nonparametric smoothing technique and conditional logistic regression. Exposure was measured by duration, intensity (mg/m(3)), and cumulative exposure (mg/m(3)-years) to each MWF type (straight, soluble, or synthetic), as well as by duration of exposure to selected metals, additives, and components of the fluids.RESULTS: When data from three plants were combined, grinding with water-based synthetic or soluble MWF increased the risk of stomach cancer mortality. Those grinding with synthetic MWF with more than 1.3 mg/m(3)-years exposure during the 10 years just prior to death experienced a 4.4-fold risk of stomach cancer (95% CI 1.5-13.1). Increased risk was also observed among those in the highest category of soluble grinding grading exposure (OR 1.9; 85% CI 1.0-3.6). In plant-specific analysis, there was evidence of increased risk of stomach cancer associated with exposure to straight MWF and iron, as well as the water-based fluids.CONCLUSIONS: Study findings suggest that stomach cancer mortality was associated with exposure to each MWF type. Results suggesting that synthetic MWF may act as a stomach cancer promoter are of particular concern because this MWF is widely used in today's high speed grinding operations.     

Dermatitis among automobile production machine operators exposed to metal-working fluids

This cross-sectional study was designed to assess differences in prevalence of contact dermatitis between machine operators exposed to metal-working fluids (MWFs) and unexposed assemblers, and to assess potential risk factors for contact dermatitis among these machine operators. In their work, machine operators were exposed to either semisynthetic or soluble oil MWFs. We evaluated 158 machine operators and 51 assemblers from one large automobile transmission plant using questionnaires, dermatologist examination of the skin, and dermal dosimetry to measure wetness and metal exposures. We found that machine operators had more combined (definite plus possible) dermatitis (27.2% vs. 13.7%, χ² = 3.9, p = 0.05, 1 df) compared with assemblers. Among machine operators, risk factors significantly associated with (combined) dermatitis were subjective assessment of wetness of the work, exposure to semisynthetic as opposed to soluble oil MWF, current cigarette smoking, and increasing worker age. These risk factors suggested preventive and control measures including control of wet work, surveillance programs including early self-report of dermatitis, consideration of replacement of semisynthetic with soluble oil MWFs, and strictly limiting smoking among machine operators exposed to MWFs. © 1996 Wiley-Liss, Inc.     

Estimation of the Probability of Exposure to Machining Fluids in a Population-Based Case-Control Study

We describe an approach for estimating the probability that study subjects were exposed to metalworking fluids (MWFs) in a population-based case-control study of bladder cancer. Study subject reports on the frequency of machining and use of specific MWFs (straight, soluble, and synthetic/semi-synthetic) were used to estimate exposure probability when available. Those reports also were used to develop estimates for job groups, which were then applied to jobs without MWF reports. Estimates using both cases and controls and controls only were developed. The prevalence of machining varied substantially across job groups (0.1–>0.9%), with the greatest percentage of jobs that machined being reported by machinists and tool and die workers. Reports of straight and soluble MWF use were fairly consistent across job groups (generally 50–70%). Synthetic MWF use was lower (13–45%). There was little difference in reports by cases and controls vs. controls only. Approximately, 1% of the entire study population was assessed as definitely exposed to straight or soluble fluids in contrast to 0.2% definitely exposed to synthetic/semi-synthetics. A comparison between the reported use of the MWFs and U.S. production levels found high correlations (r generally >0.7). Overall, the method described here is likely to have provided a systematic and reliable ranking that better reflects the variability of exposure to three types of MWFs than approaches applied in the past.

[Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resources: a list of keywords in the occupational histories that were used to link study subjects to the metalworking fluids (MWFs) modules; recommendations from the literature on selection of MWFs based on type of machining operation, the metal being machined and decade; popular additives to MWFs; the number and proportion of controls who reported various MWF responses by job group; the number and proportion of controls assigned to the MWF types by job group and exposure category; and the distribution of cases and controls assigned various levels of probability by MWF type.]     

Respiratory symptoms and lung function abnormalities among machine operators in automobile production

This cross-sectional study was designed to assess differences in prevalence of respiratory symptoms and lung function between machine operators exposed to semisynthetic or soluble metal-working fluids (MWFs) and unexposed assemblers and to assess exposure-response relationships with MWF type, total aerosol, endotoxin, culturable bacteria and fungi. We evaluated 183 machine operators and 66 assemblers from one large automobile transmission plant using questionnaires, spirometry data, and cross-shift assessment of both lung function and respiratory symptoms. We found that airborne exposures to total aerosol, endotoxin, culturable bacteria and fungi were higher in machine operations than in the assembly area. There was a correlation between bulk and airborne culturable bacteria, but not between bulk and airborne culturable fungi. Machine operators had significantly more usual cough, usual phlegm, work-related chest tightness and post-shift symptoms of chest tightness, throat irritation, and cough compared with assemblers. We found exposure-response relationships between respiratory symptoms and total aerosol, as well as culturable fungi and bacteria. Associations with endotoxin were not strong or consistent, possibly because airborne levels were generally low. Cross-shift lung function decrements did not differ between machine operators and assemblers and there were no associations with MWF or specific exposures. The finding of respiratory symptoms at low levels of exposure in this study suggests the need to re-assess total aerosol thresholds. Associations between airborne fungal exposures and respiratory symptoms need further study to characterize sources of exposure other than MWF in machining operations. Am. J. Ind. Med. 31:403–413, 1997. © 1997 Wiley-Liss, Inc.     

金属加工液接触者班前班后肺功能变化研究

  目的   调查某汽车制造企业接触金属加工液工人的呼吸系统症状,测定工人班前班后肺功能变化,以探讨金属加工液暴露对接触者呼吸系统的影响。
  方法   对观察组158名接触金属加工液的工人和对照组116名装配作业工人,进行职业健康检查和跨班肺功能测定并进行比较。
  结果   观察组作业场所检出低浓度的二乙胺、三乙醇胺。咳嗽、胸闷、气喘是金属加工液（MWF）接触工人常见的呼吸系统症状,观察组中有70例（占44.30%）工人至少出现1种呼吸系统症状,高于对照组（27例,占23.28%）（P < 0.01）。观察组班后呼气峰流速（PEF）异常率较班前升高,差异有统计学意义（P＜0.05）。与班前比较,观察组工人班后肺功能指标FEV₁、FEV₁/FVC、PEF均降低（P < 0.05）,其中FEV₁、FEV₁/FVC、PEF分别下降7.72%、4.43%、6.75%。观察组班后FEV₁/FVC、PEF低于对照组（P < 0.05）。观察组班后肺功能损伤发生率高于班前（P < 0.05）,且班后异常率高于对照组（P < 0.05）,主要表现为以FEV₁降低、伴FEV₁/FVC降低为特征的阻塞性通气功能障碍。高工龄观察组班后FEV₁、FEV₁/FVC、PEF均低于低工龄组（P < 0.05）。观察组工人班后FEV₁、FEV₁/FVC、PEF下降大于15%的工人分别占3.16%、1.90%、6.33%,有3.16%达到诊断哮喘的水平。
  结论   金属加工液接触可致呼吸系统健康危害,表现为呼吸系统症状发生率增高和肺功能下降,应加强金属加工液接触者的呼吸防护。
     

A field investigation of the acute respiratory effects of metal working fluids. I. Effects of aerosol exposures

A study of cross-shift change in pulmonary function was conducted among workers exposed to metal working fluids (MWF) in an automobile parts manufacturing company. Three hundred eighty-six workers (216 machinists exposed to straight or soluble MWFs, and 170 nonmachinists) were studied for 1 day, performing spirometry at the beginning and end of their shift. Airborne concentrations of inhalable particulate, culturable bacteria, and endotoxin were measured. We observed an approximately threefold increase in the incidence of 5% or greater cross-shift decrement in forced expiratory volume during the first second among those with exposures above about 0.15 mg/m³, compared to those with exposures below about 0.08 mg/m³. There was some evidence that chronic respiratory symptoms were more prevalent among machinists than among nonmachinists, notably for chronic cough. Baseline FEV₁ was about 3% lower on average among those with soluble MWF exposure compared to nonmachinists. These findings are consistent with earlier studies showing respiratory effects of MWFs. Am. J. Ind. Med. 31:756–766, 1997. © 1997 Wiley-Liss, Inc.     

Respiratory symptoms,ventilatory impairment,and bronchial reactivity in oil mist-exposed automobile workers

Studies concerning the respiratory effects of oil mists are sparse and contradictory. The aim of this study was to determine the respective effects of occupational exposure to straight cutting oils and soluble mineral oils on the prevalence of respiratory symptoms, ventilatory impairment, and bronchial reactivity. The population study consisted of 308 male workers of a large French car-making plant, including 40 subjects chronically exposed to straight cutting oils (group S), 51 subjects chronically exposed to soluble mineral oils (group E), 139 subjects with chronic dual exposure to straight cutting oils and soluble mineral oils (group D), and 78 unexposed assembly workers used as a control group (group C). Worker evaluation included a standardized questionnaire, measurement of pulmonary function, and a methacholine challenge. Oil mist concentration at the work place was determined by gravimetric analysis. The arithmetic mean concentration was 2.6 ± 1.8 mg/m³. The geometric mean concentration was 2.2 pm 1.9 mg/m³. The prevalence of respiratory symptoms did not differ significantly among the four groups. However, the subjects exposed to straight cutting oils (group S + group D) had a significantly higher prevalence of chronic cough and/or phlegm than the others (group E + group O): 25.7% vs. 16.3% (p = 0.048). Furthermore, the prevalence of cough and/or phlegm increased significantly (p = 0.03) with increasing duration of exposure to straight cutting oils after adjustment on smoking categories. Lung function tests did not differ significantly among the four groups but we observed a significant decrease of forced expiratory volume in 1 see (FEV₁), forced expiratory flow during the middle half of forced vital capacity (FEF_25-75), and maximal flow rate at 50% and 25% of exhaled forced vital capacity (V₅₀ and V₂₅) according to duration of exposure among smokers exposed to straight cutting oils, suggesting a synergistic effect of tobacco and insoluble oils. No effect of exposure to mineral oils on bronchial reactivity was demonstrated. It is concluded that despite low levels of pollution by oil mists, the present study has shown tenuous adverse chronic effects of straight cutting oils on respiratory symptoms and lung function. However, no adverse effect of soluble mineral oils was demonstrated. These results suggest that threshold limit values for mineral oils should be reassessed.     

Acute respiratory effects on workers exposed to metalworking fluid aerosols in an automotive transmission plant

Exposure to metalworking fluids has been linked to modest cross-shift reductions in FEV₁ and occupational asthma. To identify responsible agents, we measured personal exposures to thoracic particulate (TP), viable plus nonviable thoracic bacteria (BAC), and vapor phase nicotine (VPN) (as a surrogate for tobacco particulate) among 83 machinists exposed to soluble oils and 46 dry assemblers working in an automotive transmission machining plant using biocides infrequently. The participants completed interviews and performed pre- and postshift spirometry on Monday and Thursday of the same week in each of three rounds of data collection (June 1992, January 1993, June 1993). Generalized estimating equations were used to combine information across rounds in multiple regression models of cross-shift and cross-week changes in forced expiratory volume, I second (FEV₁) and forced vital capacity (FVC). Mean seniority was 19 years among machinists. Mean personal TP levels were 0.41 mg/m³ in machinists and 0.13 mg/m³ in assemblers. Six of the 83 machinists and none of the 46 assemblers experienced a greater than 19% cross-shift decrement in FEV₁ or FVC at least once (p = .07). In regression models using either TP or BAC, among subjects with lower baseline (Monday preshift) FEV₁/FVC ratios, increasing exposure was significantly associated with increasing cross-shift decrements in FEV₁ and FVC in linear models, and with increased likelihood of a 10% or greater cross-shift decrement in FEV₁ or FVC in logistic models. Adjustment of TP for VPN did not affect models significantly. We conclude that clinically important cross-shift decrements in pulmonary function are associated with exposure to metalworking fluid aerosols within a high-seniority population. Am. J. Ind. Med. 31:510–524, 1997. © 1997 Wiley-Liss, Inc.     

Risk of upper aerodigestive tract cancers in a case-cohort study of autoworkers exposed to metalworking fluids

Aims: To re-examine aerodigestive cancer risk in a cohort of autoworkers exposed to metal working fluids (MWF), using improved case definition and more recently diagnosed cases.

Methods: The autoworker cohort included 31 100 hourly workers alive on 1 January 1985 who worked at three automobile plants in Michigan. A case-cohort design was carried out that included incident cases of cancers of the larynx, oesophagus, and stomach, and a 10% sample of the cohort. A Cox proportional hazards model was used to estimate MWF exposure effects. The smoothing method of penalised splines was used to explore the shape of the underlying exposure-response curves.

Results: The most important finding was the association between larynx cancer incidence and cumulative straight MWF exposure. The results for oesophageal cancer were less consistent. For stomach cancer there was no evidence of excess risk.

Conclusion: This association between larynx cancer and straight MWF exposures was consistent with a previous finding in this cohort, providing further support for a causal relation.

     

A model for predicting endotoxin concentrations in metalworking fluid sumps in small machine shops

METHODS: In British Columbia, Canada, nineteen small machine shops which used water-based metalworking fluids (MWF) were examined. One bulk MWF sample was taken from each independent sump (N=140) and tested for endotoxin using the Limulus Amoebocyte Lysate assay. Factors that might influence the MWF sump endotoxin concentration were investigated using mixed effect multiple regression modelling to control for repeated measures within shops. RESULTS: The geometric mean (GM) endotoxin concentration was 6791 EU/ml. Contamination of MWF with tramp oil, MWF pH, MWF temperature, and MWF type were significant predictors of sump fluid endotoxin concentration (model P=0.0001, ordinary least squares R(2) =0.36). Concentrations of endotoxin in sump fluids were increased by MWF contamination with tramp oils such as hydraulic oils, preservative oils, spindle oils, slidway lubricants, gear lubricants, and greases (model predicted GM=17400 EU/ml vs. 1600 EU/ml without tramp oil). Concentrations were also elevated where pH was lower than 8.5 (predicted GM=10600, vs 3600 EU/ml for pH 8.5 to 9.5), where soluble fluids were used (predicted GM=11800 vs. 2800 EU/ml for synthetic fluids), and where sump fluid temperatures were higher (predicted GM=2600 EU/ml at 11 degrees C vs. 21500 EU/ml at 32 degrees C). The within-shop correlation of sump bulk fluid endotoxin concentrations was 38%. CONCLUSIONS: Minimizing tramp oil contamination, using synthetic fluids, and monitoring pH and temperature would be valuable tools for controlling endotoxin contamination in MWF sumps. In addition, since there was correlation within-shop, contamination of one sump in a shop may suggest changing the fluids in all.     

Mortality studies of machining fluid exposure in the automobile industry IV; a case-control study of lung cancer

Machining fluids are diverse products that contain numerous additives and contaminants, including polycyclic aromatic hydrocarbons. Studies treating machining fluids as an aggregate exposure have found both positive and negative associations with lung cancer. In this nested case-control study of automotive workers (667 cases and 3,041 matched controls), individual estimates of exposure quantity and duration for specific classes of machining fluids were derived. An inverse dose-response relationship was found between synthetic machining fluids and lung cancer mortality, with an odds ratio of 0.6 (95%Cl = 0.4, 0.8) for the highest level of lifetime exposure. The relationship was strongest for recent exposures. There was little evidence of an association with soluble or straight oil machining fluids. Risks were inconsistently elevated in workers exposed to aluminum. Results from this study provide strong evidence that exposure to machining fluids is not associated with an increased risk of lung cancer mortality in automotive workers. Am. J. Ind. Med. 31:525–533, 1997. © 1997 Wiley-Liss, Inc.     

Role of underlying pulmonary obstruction in short-term airway response to metal working fluid exposure: a reanalysis

BACKGROUND: Among epidemiologic studies that found evidence for associations between exposures to metal working fluids (MWF) and pulmonary function impairments, one found effects restricted to workers with fixed obstruction at baseline. We reanalyzed a previously published study on MWF exposure and cross-shift pulmonary function to further evaluate this finding. METHODS: Pulmonary function was measured cross-shift on Monday and Friday in 131 male automotive workers. Quantitative personal MWF exposure data were available. Those with an FEV(1)/FVC ratio of 相似文献   

Association between use of synthetic metalworking fluid and risk of developing rhinitis-related symptoms in an automotive ring manufacturing plant

The main objective of this study was to determine the association between synthetic metalworking fluid (MWF) and rhinitis-related symptoms. At a plant manufacturing piston rings for automobiles, we interviewed grinders (19) and manufacturing workers (142) in operations where synthetic or semisynthetic MWF is handled, and administrative office workers (44) regarding the principal symptoms of rhinitis (nasal stuffiness, runny nose, anosmia, nasal itchiness, rhinorrhea, headache, epistaxis, and post-nasal drip). In addition, we assessed the current exposure of workers handling MWF to MWF aerosols, fungi, and endotoxins. Logistic regression analysis was used to examine the association between MWF surrogates indicative of MWF exposure and each rhinitis-related nasal symptom. Odds ratios (ORs) and 95% confidence intervals were adjusted for sex, age, smoking habit, and duration of employment. Among grinders handling synthetic MWF, the frequency of complaints of the dominant symptoms was 66.7% for nasal stuffiness, 77.8% for anosmia, 77.8% for runny nose, and 50.0% for headache. These rates are quite high even allowing for the common occurrence of rhinitis in the general population. Twenty eight of 34 grinding and manufacturing workers (82.4%) sampled were exposed to MWF mist above the threshold limit of 0.2 mg/m(3) listed as a notice of intended change by the American Conference for Governmental Industrial Hygienists (ACGIH). The percentage of workers exposed to MWF mist >0.5 mg/m(3) was 17.6%. Most workers were exposed to fungi levels >103 CFU/m(3). All exposures to endotoxins were <50 EU/m(3). Logistic regression analysis found that use of synthetic MWF was significantly associated with excess risk of nasal stuffiness (OR 3.5), nasal itchiness (OR 2.0), and runny nose (OR 2.1). The use of semi-synthetic MWF had little or no impact on the risk of developing rhinitis-related nasal symptoms. Grinding workers handling synthetic MWF had an increased risk of nasal stuffiness (OR 7.9), anosmia (OR 23.2), nasal itchiness (OR 8.3), runny nose (OR 20.4), post nasal drip (OR 18.4), and headache (OR 7.4) compared to administrative workers. Synthetic MWF may play an important role in the development of the dominant symptoms of rhinitis. Further study is needed to establish the risk of rhinitis or rhinitis-related symptoms according to MWF type.     

Causes of death among workers in a bearing manufacturing plant

Recent studies identify digestive cancer excesses among workers exposed to cutting fluids, abrasive dusts, and oil smoke. Standardized proportional mortality and mortality odds ratio studies were carried out for a ball bearing plant. Cause of death and work histories were obtained for 702 of 768 hourly employees with ten or more years' service who died between 1969 and 1982. Union and company records were used to define exposure measures. The major findings were significant excesses in proportional mortality ratios (PMR) from stomach cancer (PMR = 2.0) and rectal cancer (PMR = 3.1) among white men. After control for age at death, there was a significant association between stomach cancer and precision grinding exposures, consisting primarily of direct contact with water-based cutting fluids (usually emulsified oils) and their aerosols. Some straight oils and synthetic cutting fluids were used as well. The pattern of stomach cancer is consistent with previous findings and suggests an association with the soluble oil cutting fluids.     

Mortality studies of machining fluid exposure in the automobile industry III: A case-control study of larynx cancer

A case-control study of larynx cancer was conducted within a cohort of automobile workers exposed to metal working fluids, commonly referred to as machining fluids (MF). Results are based on 108 cases of larynx cancer and 5:1 matched controls. Risks associated with specific types of MF, as well as specific components of the fluids were evaluated. Based on a retrospective exposure assessment, lifetime exposures to straight and soluble fluids, grinding particulate, biocides, selected metals, sulfur, and chlorine were examined. Exposure to asbestos and acid mists at two of the three study sites was also characterized. Results suggest that straight mineral oils are associated with almost a two-fold excess in larynx cancer risk. There was also evidence of an association with elemental sulfur, commonly added to straight MF to improve the integrity of the materials under extreme pressure and heat. It is not clear whether sulfur is causally related to an excess relative risk of larynx cancer or whether the observed association is the result of unmeasured confounding by another contaminant or process feature. For example, the high stress operations that require MF enriched with sulfur are also more likely to produce polycyclic aromatic hydrocarbons (PAHs) during the process. Thus, the observed association with sulfur may be due to an association with PAH. The finding of excess risk of laryngeal cancer associated with MF is consistent with several previous reports in the literature. This is the first study, however, to distinguish straight mineral oils from other types of MF. Based on these findings, a general reduction in concentrations of straight mineral oil particulate in occupational environments would be prudent.