Biomedical subjects

M B Schenker

Publications and source records attributed to M B Schenker.

At least 37 records · Page 2Linked to original sources

PubMed1996

Preventive medicine and health promotion are overdue in the agricultural workplace.

Agriculture was one of the earliest industries in which occupational hazards were recognized, but it has been largely excluded from the mainstream of modern preventive medicine and occupational health efforts. This resulted from the heavy industry focus of occupational medicine, from the agrarian myth which stated that work in agriculture was a healthy employment, from the widely dispersed, often family-centered, nature of farming, and from neglect of migrant and seasonal farmworker populations. Since the middle of this century it has been recognized that agriculture is one of the most hazardous major industries, but whereas the injury and fatality rates in other hazardous industries (e.g. mining, construction) have fallen substantially, there has been no comparable decline in agriculture. In addition to occupational injuries and fatalities, there is a wide range of chronic diseases that result from agricultural exposures. These include musculoskeletal, respiratory, dermatologic and reproductive disorders. Hearing loss is increased among farmers, several cancers have been associated with farming or agricultural exposures, and increased suicides have been observed in some farming populations. Recommendations for disease prevention and health promotion must be sensitive to the unique nature of farming, including the demographically different farmer, farm family, and hired farmworker populations. Approaches discussed in the paper include engineering changes, education with evaluation of its effectiveness, and enforcement of appropriate laws.

Accidents, Occupational↗

PubMed1995

Determinants of disability in illnesses related to agricultural use of organophosphates (OPs) in California.

Organophosphate (OP)-related illness data reported to the Worker Health and Safety Branch (WH&S) at the California Department of Food and Agriculture (CDFA, now Cal-EPA) in the years 1984-1988 were examined. Eight hundred and seventy-eight cases with systemic illness and 199 cases of skin disease or eye injury were identified. Systemic cases were divided into two outcome groups: (1) "severe," disability and/or hospitalization days (n = 361), and (2) "mild," no disability or hospitalization days (n = 372). For the remainder (n = 145) or 16.5% of the cases, illness severity could not be determined. Using multiple logistic regression, independent predictors of "severe" illness were identified among the systemic cases. Workers coming in contact with OP residue on commodities or in the field ("exposed to residue" or ER) (OR = 4.6, 95% CI = 3.03-7.07) and mixer/loaders/applicators (MLA) (OR = 4.1, 95% CI = 2.72-6.07) were at significantly increased risk of severe illness when compared with cases exposed to OP application drift. Cases with a Spanish surname were also at increased risk of severe illness (OR = 1.8, 95% CI = 1.25-2.73). Increased numbers of OPs per exposure were also associated with severe illness (p < 0.001). Among cases who were exposed to only one OP, severe systemic cases were more likely than mild systemic cases to be associated with exposure to diethyl than dimethyl compounds (OR = 1.6, 95% CI = 1.09-2.38). Severe systemic cases were also more likely than severe skin/eye cases to be associated with exposure to OPs with high toxicity (OR = 5.5, 95% CI = 2.42-12.60) and with exposure to diethyl groups (OR = 4.8, 95% CI = 1.90-12.00). These findings suggest that reducing exposure to OP residues, to OPs with diethyl groups, and to multiple OPs, and exposure during mixer/loader/applicator activities would reduce the risk of OP-related illness.

Adolescent↗

PubMed1995

Respiratory cancer and other chronic disease mortality among silicotics in California.

Silicotics have increased mortality from tuberculosis (TB) and from nonmalignant respiratory diseases (NMRD), including silicosis and silicotuberculosis. Since the publication of the International Agency for Research on Cancer monograph in 1987 indicating that silica was a probable human carcinogen, there has been an extensive debate about the cancer risks among silicotics. The authors identified 590 claims for silicosis among a registry of lung diseases compiled from California Workers' Compensation cases from 1945 to 1975. Using state vital records, we determined the mortality risks from 1946 to 1991. Our findings confirmed that these claimants had a significantly elevated risk for all causes of death with a standardized mortality ratio (SMR) of 1.30 (95% confidence interval [CI] = 1.18, 1.43); TB had a SMR of 56.35 (95% CI = 41.10, 75.40) and NMRD a SMR of 3.80 (95% CI = 3.11, 4.60). Cancers of the trachea, bronchus, and lung had a SMR of 1.90 (95% CI = 1.35, 2.60). For malignancies of the large intestine, there was a previously unreported SMR of 2.08 (95% CI = 1.14, 3.50). Mortality from all diseases of the heart was significantly less than expected with a SMR of 0.68 (95% CI = 0.55, 0.83); cancers of the prostate and lymphatic system were also significantly low with SMRs of 0.26 (95% CI = 0.03, 0.94) and 0.17 (95% CI = 0.04, 0.97), respectively. Workers with silicosis should be warned about these chronic disease risks, and prevention efforts to control occupational silica dust exposure should become a higher priority.

Aged↗

PubMed1995

Association of spontaneous abortion and other reproductive effects with work in the semiconductor industry.

This study tested the hypothesis that fabrication room (fab) work in the silicon-based semiconductor industry is associated with an increased risk of spontaneous abortion (SAB). The study was conducted nationwide at 14 companies representing a spectrum of large to small manufacturers. A small increase in risk of SAB was observed among fab workers compared with nonfabrication room (nonfab) workers in two cohorts, historical (adjusted RR = 1.43, 95% confidence interval [CI] 0.95-2.09) and prospective (adjusted RR = 1.25, 95% CI = 0.63-1.76). Analysis of specific fab exposures in the historical cohort showed a consistent, dose-response association of SAB with photoresist and developer solvents, whose major component was ethylene-based glycol ethers. The consistency of our findings and the toxicological data for these agents suggest that this is a causal association. Independent associations of SAB with self-reported stress and with etching fluorides were observed and require further research. No significant decrease in fertility was observed among men or women working in fabs, but reduced fecundability was suggested for some women fab workers.

Abortion, Spontaneous↗

PubMed1995

Tiered exposure-assessment strategy in the Semiconductor Health Study.

The Semiconductor Health Study included 14 U.S. companies with 82 silicon-based wafer-fabrication rooms and a complex array of processes and chemicals. Its epidemiologic components were a historical examination of spontaneous abortion rates among 902 women, a prospective evaluation of reproductive outcomes in 483 women, and a cross-sectional review of male fertility and of respiratory, ergonomic, neurologic, or gastrointestinal problems among 3,175 men and women. Designing an exposure assessment strategy presented unique problems, and multiple agents had to be evaluated. A three-tiered approach to exposure assessment was developed to reflect increasing specificity of exposures. At the first tier, employees were divided into fabrication and nonfabrication groups. At the second tier, work groups with qualitatively different exposures were determined. At the third tier, intensity of exposures to specific chemical, physical, and ergonomic agents was evaluated. Evaluations were based on worker reports of tasks performed, moderated by fabrication-specific factors observed by study industrial hygienists during site visits.

Data Collection↗

PubMed1995

Patterns of chemical use and exposure control in the Semiconductor Health Study.

Information on chemical use and exposure control between 1986 and 1990 was collected from 14 companies participating in the Semiconductor Health Study. Questionnaires and site visits provided data used to develop exposure categories for three epidemiological studies: prospective, historical, and cross-sectional. Patterns of use of target chemicals were compiled for 82 silicon-wafer fabrication rooms (fabs), including 47 from which subjects were selected for study. Chemical use was examined by operation, year, and epidemiological component. Target agents for epidemiological analyses were present in more than 50% of fabs. Use of these agents was fairly constant from 1986 to 1990, except for a moderate increase in use of propylene glycol monomethyl ether acetate, a solvent being substituted for ethylene-based glycol ethers (EGE) in photoresists. The distribution of personal protective equipment, engineering controls, and other factors potentially affecting employee exposure was also examined. Controls designed to manage processes or high acute toxicity were present in most fabs; their prevalence remained unchanged from 1986 through 1990. Controls designed to reduce exposures to chemicals with low acute toxicity were less widely distributed; their prevalence increased moderately from 1986 to 1990.

Drug-Related Side Effects and Adverse Reactions↗

PubMed1995

Algorithms for estimating personal exposures to chemical agents in the Semiconductor Health Study.

For exposure assessment in a series of epidemiologic studies of semiconductor industry workers, estimates of potential personal exposures to selected chemical agents were developed using a set of algorithms. A worker's total exposure to each agent was defined as the sum of task scores for each task using that agent. Task scores were calculated as the intensity and frequency score for each task, modified by a factor indicating degree of presence of the target agent and a process-specific emission factor representing degree of emission control present for that process. The algorithms used multiple sources of information to generate an exposure score for each worker-process-agent combination. Exposure scores were then placed into ordinal categories of exposure (0-3) for use in the epidemiologic analysis.

Algorithms↗

PubMed1995

Hierarchical cluster analysis for exposure assessment of workers in the Semiconductor Health Study.

The fabrication of integrated circuits in the semiconductor industry involves worker exposures to multiple chemical and physical agents. The potential for a high degree of correlation among exposure variables was of concern in the Semiconductor Health Study. Hierarchical cluster analysis was used to identify groups or "clusters" of correlated variables. Several variations of hierarchical cluster analysis were performed on 14 chemical and physical agents, using exposure data on 882 subjects from the historical cohort of the epidemiological studies. Similarity between agent pairs was determined by calculating two metrics of dissimilarity, and hierarchical trees were constructed using three clustering methods. Among subjects exposed to ethylene-based glycol ethers (EGE), xylene, or n-butyl acetate (nBA), 83% were exposed to EGE and xylene, 86% to EGE and nBA, and 94% to xylene and nBA, suggesting that exposures to EGE, xylene, and nBA were highly correlated. A high correlation was also found for subjects exposed to boron and phosphorus (80%). The trees also revealed cluster groups containing agents associated with work-group exposure categories developed for the epidemiologic analyses.

Cluster Analysis↗

PubMed1995

A model for assessing occupational exposure to extremely low-frequency magnetic fields in fabrication rooms in the Semiconductor Health Study.

A model was created to assess occupational exposure to extremely low-frequency magnetic fields (ELF-MF) among semiconductor fabrication-room (fab) workers. This model was based on the assumption that each subject's exposure arose from being near identifiable ELF-MF sources or being in areas with high ELF-MF levels. To assess ELF-MF exposures, the model superimposed subjects' time-activity patterns (patterns of how and where they spent their time) with measurements of magnetic-field levels from devices and work areas. This model, which was validated by personal dosimetry on 192 persons in three fabs, predicted actual time-weighted average exposures with a correlation coefficient of 0.62. The inability of the model to predict individual exposures more accurately was attributed to unforseen sources of elevated ELF-MF (transformers, distribution panels, sources in adjacent rooms) or to errors in subjects' judgments of time spent near devices. These unpredictable errors are intrinsic to the method used to estimate exposure.

Electromagnetic Fields↗

PubMed1995

Historical cohort investigation of spontaneous abortion in the Semiconductor Health Study: epidemiologic methods and analyses of risk in fabrication overall and in fabrication work groups.

The risk of spontaneous abortion (SAB) in the semiconductor industry was examined in a historical cohort study of pregnancies at 14 companies. We identified female employees who had worked for at least 6 months and whose ages ranged from 18 to 44 years during the 1986-1989 study period. Using company records, we included all fabrication-room (fab) employees and an approximately equal number of nonfabrication (nonfab) employees, for a total sample of 7,269. Telephone interviews with 6,088 women (84%) identified 904 eligible pregnancies and 113 SABs. Exposure classification was based on questionnaire and industrial hygiene assessments of tasks the women performed during the first trimester of pregnancy. Using logistic regression to control for age, smoking, ethnicity, education, income, year of pregnancy, and stress, we found a higher risk of SAB in fab employees than in nonfab employees (15.0% of fab pregnancies ended in SAB vs. 10.4% of nonfab pregnancies, adjusted relative risk [RR] = 1.43, 95% CI = 0.95-2.09). Analysis of fab work groups showed that the highest relative risk was in masking employees (17.5% SAB rate, adjusted RR = 1.78, 95% CI = 1.17-2.62 in comparison with nonfab employees). Within masking, the highest risk was found in etching-related process employees (22.2% SAB rate, adjusted RR = 2.08, 95% CI = 1.27-3.19 in comparison to nonfab employees.

Abortion, Spontaneous↗

PubMed1995

Historical cohort study of spontaneous abortion among fabrication workers in the Semiconductor Health Study: agent-level analysis.

Risk of spontaneous abortion (SAB) was examined in relation to chemical and physical agents in a retrospective study of employees of 14 seminconductor manufacturers: After screening over 6,000 employees, 506 current and 385 former workers were eligible. If a woman had multiple eligible pregnancies, one was selected at random. Telephone interviews provided data on demographics and occupational and other exposures during the first trimester. Two groups of chemicals accounted for the 45% excess risk of SAB among fabrication-room (fab) workers: photoresist and developed solvents (PDS), including glycol ethers, and fluoride compounds used in etching. Women exposed to high levels of both these agents were at greater risk (RR = 3.21, 95% confidence interval [CI] = 1.29-5.96). In fab workers without these exposures, SAB rates were not elevated (adjusted relative risk [RR] = 0.98, 95% CI = 0.55-1.69). An association was seen with workplace stress, which was not limited to women exposed to PDS or fluoride, nor did stress explain the associations between these chemicals and SAB.

Abortion, Spontaneous↗

PubMed1995

Epidemiologic methods for prospective assessment of menstrual cycle and reproductive characteristics in female semiconductor workers.

Methods were developed to assess potential adverse effects of semiconductor fabrication work in a prospective study of reproductive health. All women aged 18-44 years who worked in seven silicon-wafer fabrication sites in five companies and a frequency-matched sample of women in nonfabrication jobs were included. Among 3,480 selected for screening, 2,639 (75%) completed a self-administered questionnaire to identify women at risk of pregnancy. Among the 739 (28%) eligible women, 481 (65%) completed baseline interviews and 402 (83.6%) completed at least one menstrual cycle of follow-up by providing daily diaries and daily urine samples. Menstrual cycle characteristics were assessed from questionnaires and diaries. Urine samples were assayed for reproductive hormones to identify conceptions. The usual cycle length recalled at baseline was 28 days. The mean cycle length (MCL) recorded in diaries was 29 days, with greater dispersion than at baseline. The median of the MCL from diary data was 28 days for women reporting regular cycles at baseline but 34 days for women reporting irregular cycles at baseline, and the median standard deviation in cycle length per woman was 2.5 days and 7.5 days, respectively. The prospective method, while expensive and labor intensive, showed good compliance. Nevertheless, recall also provided reasonably accurate estimates and distinguished women with regular and irregular cycles.

Adolescent↗

PubMed1995

Prospectively assessed menstrual cycle characteristics in female wafer-fabrication and nonfabrication semiconductor employees.

Women aged 18-44 years in silicon-wafer fabrication-room (fab) jobs and frequency-matched women in nonfab jobs were screened for a prospective study of reproductive health (n = 2,639). Among the 739 (28%) eligible women, 481 (65%) completed a baseline interview; 402 completed at least one menstrual cycle of follow-up with daily diaries and urinary assays to exclude conceptive cycles. Adjusted mean cycle lengths (MCL) did not differ between fab and nonfab women (p = 0.97). Women working in thin film and ion implantation (TFII) had the highest adjusted MCL (34.8 +/- 1.7 days) compared with nonfab workers (32.5 +/- 1.4 days, p = 0.07). Among women working exclusively in one group, TFII women had significantly higher MCL (36.1 +/- 2.04 days) than nonfab women (32.0 +/- 1.38 days, p = 0.017). TFII women were also more likely to have all cycles > 35 days (adjusted relative risk [RR] = 2.45; 95% CI = 0.85-6.06). Variability was assessed by logarithmic transformation of the mean standard deviation (MLSD) in cycle length per woman and adjusted for age and ethnicity (4.5 days for fab vs. 4.0 days for nonfab, p = 0.16). Women working exclusively in TFII or photolithography (PHOTO) had significantly higher adjusted MLSD in cycle length (6.68 +/- 1.28 and 5.72 +/- 1.24 days, respectively) than women in nonfab (4.1 +/- 1.16 days, p = 0.013 and 0.019, respectively). Fab and nonfab women did not differ significantly in mean days of bleeding or risk of having cycles > 35 or < 24 days. However, elevated risks of having cycles < 24 days were seen in supervisor engineers (adjusted RR = 2.46, 95% CI = 1.19-3.63) and PHOTO women (adjusted RR = 1.83, 95% CI = 0.94-2.88).

Adolescent↗

PubMed1995

Prospective assessment of fecundability of female semiconductor workers.

To investigate a possible effect of reduced fecundability (probability of conception per menstrual cycle) among women who fabricate silicon wafers, 152 fabrication-room (fab) and 251 nonfab workers were followed for an average of five menstrual cycles. Daily urine samples were analyzed to confirm clinical spontaneous abortions (SABs) and early fetal losses (EFLs). Adjusted fecundability odds ratios (FRs) for fab workers ranged from 0.59 to 0.72 (p = 0.09-0.28 vs. nonfab). For clinical pregnancies only, the adjusted FR ranged from 0.43-0.50 (p = 0.04-0.09 vs. nonfab). This lower fecundability was most pronounced among dopants and thin-film workers [adjusted FR = 0.61, 95% confidence interval (CI) = 0.27-1.40 for all pregnancies; adjusted FR = 0.22, 95% CI = 0.05-0.96 for clinical pregnancies] and in workers exposed to ethylene-based glycol ethers (adjusted FR = 0.37, 95% CI = 0.11-1.19).

Abortion, Spontaneous↗

PubMed1995

Prospective monitoring of early fetal loss and clinical spontaneous abortion among female semiconductor workers.

Women who work in silicon wafer fabrication rooms (fabs) have been reported to have an increased risk of spontaneous abortion (SAB). Although previous studies have included only clinically recognized SABs, more than two-thirds of SABs may be clinically unrecognized. To determine whether fab work is associated with SAB, we recruited 152 fab and 251 nonfab workers, who collected urine samples for a 6-month period. Samples were analyzed by immunoradiometric assay for the presence of human chorionic gonadotropin to detect early fetal losses. Approximately 63% of fab and 46% of nonfab pregnancies ended in SAB [adjusted relative risk (RR) = 1.25; 95% confidence interval (CI) = 0.63-1.76]. Similar RR were seen for women who worked in dopant and thin-film processes (adjusted RR = 1.30; 95% CI = 0.51-1.96) or in masking (adjusted RR = 1.30; 95% CI = 0.59-1.84). The four pregnancies among women who worked with ethylene-based glycol ethers ended in SAB.

Abortion, Spontaneous↗

PubMed1995

A cross-sectional survey of respiratory and general health outcomes among semiconductor industry workers.

As part of the Semiconductor Health Study, we performed a cross-sectional survey to assess prevalence of specific nonreproductive health outcomes and their association with occupational exposures. A total of 3,175 persons from eight manufacturing sites across the U.S. completed a health and work questionnaire (78% participation rate). After adjusting for confounders, responses from fabrication room (fab) workers indicated a greater risk than those of nonfab workers for upper respiratory symptoms (relative risk [RR] = 1.08; 95% confidence interval [CI] = 1.03-1.13); a dose-response effect with hours per day spent in fabs was observed. Fab workers also had greater prevalence for persistent wheezing (RR = 1.82; 95% CI = 1.15-2.87), dermatitis within the past year (RR = 1.19; 95% CI = 1.04-1.35), and alopecia (RR = 1.73; 95% CI = 1.16-2.54). Female sex, a somatization index score, and smoking were important nonoccupational covariates. Increased respiratory symptoms may result from occupational exposures in fabs; further research is needed to identify causal agents and develop prevention strategies.

Adult↗

PubMed1995

A cross-sectional study of musculoskeletal symptoms and risk factors in semiconductor workers.

As part of the cross-sectional component of the Semiconductor Health Study, we assessed prevalence of specific musculoskeletal symptoms and their association with possible ergonomic risk factors. A total of 3,175 persons (78% participation rate) from eight manufacturing sites across the U.S. completed a health and work questionnaire. Using logistic regression methods to adjust for nonoccupational factors, we compared musculoskeletal symptom (self report) prevalence among fabrication room (fab) and nonfab workers, among specific work process groups, and among workers exposed to selected ergonomic stressors. Overall, seven of 12 musculoskeletal outcomes were significantly more prevalent among fab workers. Distal upper-extremity symptoms were more common among fab than nonfab workers [relative risk (RR) = 1.44, 95% confidence interval (CI) = 1.26-1.63] and showed a dose-response effect with hours per day spent in the fab; increased risk was associated with frequency of lifting and with use of vacuum wands and projection aligners. Female sex and high somatization index score were associated with increased reporting for all musculoskeletal outcomes.

Adult↗

PubMed1995

Fertility history of currently employed male semiconductor workers.

Fertility among men working in semiconductor manufacturing during 1984-89 was assessed in a 1990-91 cross-sectional study of eight companies. Men working in wafer fabrication rooms (fabs) (n = 241, 165 births) were compared to men in nonfabrication (nonfab) jobs (n = 447, 300 births). Results showed that 17% of fab men and 14% of nonfab men reported ever trying for > or = 1 year to conceive [relative risk (RR) = 1.21, 95% confidence interval (CI) = 0.83-1.74]. Crude birth rates (births/1,000 person months) were similar [15 fab, 17 nonfab; crude fertility ratio (FR) = 1.09, 95% CI = 0.86-1.36], as were birth rates adjusted by Cox models for confounders (adjusted FR = 0.98, 95% CI = 0.80-1.19, p = 0.79). Fab men who worked in furnace, thin-film, or ion implantation areas were more likely than nonfab men to report previous difficulty conceiving (25%, RR = 1.79, 95% CI = 1.09-2.94), and their past fertility was lower (nine births/1,000 person months; crude FR = 0.66, 95% CI = 0.40-1.02; adjusted FR = 0.73, 95% CI = 0.50-1.09, p = 0.12). Problems included lack of contraception data and misclassification of fab subgroups.

Cross-Sectional Studies↗