Nonfatal occupational injury among California farm operators.

We conducted a population-based telephone survey addressing farm-work-related (FWR) injuries among California farm operators. Of 1947 participants (80.4% response), 135 farm operators reported 160 FWR injuries in the preceding year, yielding a one-year cumulative incidence for any FWR injury of 6.9% (95% CI 5.8%-8.2%), or a mean 8.2 FWR injuries per 100 farmers in the preceding year (95% CI 6.8-9.7). Multiple injury events in the same individual occurred more frequently than predicted by chance. Sprains and strains (29.4%) were the most frequently reported injury and predominantly involved the back. Overexertion represented the most frequent external cause (24.2%), followed by machinery (14.3%), falls (13.0%), and animals (12.4%). Factors associated with FWR injury included white ethnicity (OR 3.19; 95% CI 1.38-7.36), increased annual hours worked on the farm, low levels of administrative work, and increased percentage of time working with livestock. FWR injury experience of California farm operators is comparable with that reported for other agricultural populations. Above-expected frequency of multiple injuries supports involvement of personal or environmental risk factors. Preventive efforts should focus on higher-risk groups and preventing overexertion and muscle strain and injury related to machinery, falls, and animals, especially livestock.

Breast cancer stage at diagnosis in relation to duration of medicaid enrollment.

BACKGROUND: Stage at diagnosis has been used to compare the quality of cancer screening services by health insurance type, using membership at diagnosis or treatment. This study evaluates breast cancer stage among women on Medi-Cal, California's Medicaid program, in relation to duration of coverage to assess the impact of including women with recently acquired benefits in the Medi-Cal group. METHODS: Breast cancers diagnosed in 1993 among women ages 30 to 64 were obtained from the statewide, population-based cancer registry and linked to Medi-Cal enrollment files. Women on Medi-Cal when diagnosed were categorized based on months covered during the 12 months preceding diagnosis (12, 1-11, or none), and compared with all other women with breast cancer. Logistic regression models measured the effect of duration of Medi-Cal coverage on the odds of late-stage disease, controlling for demographic, socioeconomic, health access, and tumor characteristics. RESULTS: Among women with Medi-Cal benefits when diagnosed, 18% were not covered during the year preceding diagnosis, and late-stage disease was common among these women. The odds ratio for late-stage disease among all women on Medi-Cal was 1.67 (95% CI 1.41, 1.97), but was reduced by 42% to 1.39 (95% CI 1.15, 1.67) when women without benefits before diagnosis were excluded from the Medi-Cal group. CONCLUSIONS: Women with Medi-Cal benefits before diagnosis were more likely to be diagnosed with late-stage disease than other women with breast cancer. However, the practice of assigning health insurance status based on enrollment at diagnosis underestimates the effect of access to breast cancer screening through Medicaid.

Ethnic differences in adolescent substance initiation sequences.

OBJECTIVES: To evaluate ethnic differences in the initiation sequences of tobacco, alcohol, marijuana, and cocaine use among US high school students and to determine if ethnicity is a predictor of progression from licit to illicit substances or initiation of illicit substances before licit substances. DESIGN: Cross-sectional analyses of the Centers for Disease Control and Prevention's 1995 Youth Risk Behavior Survey. SETTING: US high schools. PARTICIPANTS: A total of 8550 high school students randomly selected by cluster design. MAIN OUTCOME MEASURES: Respondents were categorized based on self-reported sequence of initiating substances as follows: none, licit substances only, licit substances then illicit substances (typical), illicit substances first (reverse), and licit and illicit substances at the same time (concurrent). RESULTS: Adjusting for age, maternal education, and region, progression from licit to illicit substances was significantly associated with black ethnicity (odds ratio [OR], 1.5; 95% confidence interval [CI], 1.04-2.1) and male sex (OR, 1.4; 95% CI, 1.2-1.6). Black male and Latino female students whose mothers completed at least high school were more likely than white students with similarly educated mothers to initiate illicit substances before licit substances (OR, 3.0; 95% CI, 1.7-5.3; and OR, 5.9; 95% CI, 1.7-20; respectively). Similar trends were noted for the concurrent sequence. CONCLUSIONS: The pattern of initiating tobacco, alcohol, marijuana, and cocaine use differs by ethnicity. Maternal education may be a proxy variable for other significant risk factors.

Injury death excesses in smokers: a 1990-95 United States national cohort study.

OBJECTIVES: Assess injury death relative risks (RR), dose-response, and attributable fractions for current cigarette smokers (smokers) in a recent representative sample of the United States population without and with adjustment for (a) demographic and (b) additional behavioral risk factors. SETTING: United States. METHODS: National Health Interview Survey (NHIS) adult (ages 18+ years) interviewees from 1990 or 1991 were followed through 1995. Referents had never smoked a total of 100 cigarettes. Relative risks were estimated with Stata software's Cox proportional hazard regressions, using NHIS final weights and primary sampling units. The resulting RR and published data were used to estimate population smoking attributable fractions of injury deaths in the United States. RESULTS: The crude, age-race-gender adjusted, and fully (demographic plus educational attainment, marital status, alcohol use level, and seat belt use) adjusted RRs for injury death in smokers were 1.86 (95% confidence interval (CI) 1.30 to 2.66), 1.60 (CI 1.12 to 2.29), and 1.42 (CI 0.99 to 2.05) respectively. Those RRs correspond to United States injury death smoking attributable fractions of 18%, 13%, and 9%, respectively. Those smoker/ injury death RRs each showed a significant dose response relationship (p<0.030). Smokers' unadjusted unintentional injury, motor vehicle crash, and suicide RRs were 1.87 (CI 1.22 to 2.86), 2.14 (CI 1.12 to 4.11), and 2.17 (CI 1.02 to 4.62), respectively. CONCLUSIONS: Smokers in the United States have significant dose-response excesses of injury death, independent of age, race, gender, alcohol use, seat belt use, education, and marital status. This supports earlier studies suggesting that smoking may be a leading contributor to injuries and injury may be a leading burden from smoking, both nationally and globally.

Maternal supplemental and dietary zinc intake and the occurrence of neural tube defects in California.

The authors investigated the association between maternal preconceptional supplemental and dietary zinc intake and risk of neural tube defects (NTDs) in a population-based case-control study conducted between 1989 and 1991 in California. Cases were 430 NTD-affected fetuses/infants, and controls were 429 randomly selected non-malformed infants. Mothers reported their preconceptional use of vitamin, mineral, and food supplements, and completed a 98-item food frequency questionnaire. Increased total preconceptional zinc intake was associated with a reduced risk for NTDs (quintile 5 vs. quintile 1, odds ratio (OR) = 0.65, 95% confidence interval (CI) 0.43, 0.99). Phytate intake, a constituent of the diet known to impede zinc absorption, appeared to modify the zinc - NTD association. In addition, increased servings of animal products, the most bioavailable food source of zinc, was associated with a reduced risk for NTDs (quintile 5 vs. quintile 1, OR = 0.49, 95% CI 0.32, 0.76). Risk estimates for zinc intake were changed little after controlling for multiple sociodemographic factors and total folate intake, but were attenuated after controlling for nutrients highly correlated with dietary sources of zinc, such as protein. In sum, the analyses indicate that risk of NTDs in infants and fetuses decreased with increasing maternal preconceptional zinc intake. However, it remains unclear whether increased zinc intake, or another nutrient or combination of nutrients highly correlated with zinc intake in the diet, is causally associated with reduced NTD risk.

Continuously recorded suckling behaviour and its effect on lactational amenorrhoea.

The hypothesis that the month-specific rate of return to ovarian cyclicity after childbirth is causally related to suckling pattern was tested for a population of New Mexican women recruited within the service area of New Mexico Highlands University and for a nationwide USA subpopulation of women recruited through membership of the Couple to Couple League (CCL). Survival analysis for time-dependent covariates was used, and significant predictors of the first postpartum menses were found. Important differences were detected in the suckling pattern for the two groups and a 5:2 differential was found in their respective rates of menstrual cycle recovery. Although the two groups were comparable perinatally, daily and time-windowed breast-feeding performance fell off at twice the rate for the New Mexico population when contrasted with the CCL sample. For both populations, the introduction of solid feeds was a strong and significant predictor of returning menstrual cyclicity, independent of suckling pattern.

PIP: This study hypothesizes that the pattern of suckling behavior throughout the day and night significantly affects the timing of postpartum menstrual cycle recovery. The study was tested in New Mexican women recruited within the service area of New Mexico Highlands University and US women recruited nationwide through the Couple to Couple League (CCL). Survival analysis for time-dependent covariates found significant predictors of the first postpartum menses. Important differences were detected in the suckling pattern for the two groups, and a 5:2 differential was found in their respective rates of menstrual cycle recovery. Results of the analysis associate the mother's separation from her baby in order to work outside the household with a drastic shortening of the postpartum amenorrhoeic interval. Although both groups showed a significant dependence on breast-feeding performance and on the delay of solid feeds for the maintenance of postpartum amenorrhoea, daily and time-windowed breast-feeding, in the New Mexico population performance fell off at twice the rate of that of the CCL sample. Thus, the introduction of solid feeds was a strong and significant predictor of returning menstrual cyclicity, independent of suckling pattern.

Reproductive health outcomes among female flight attendants: an exploratory study.

Recent studies have suggested that female flight attendants may experience increased rates of spontaneous abortion. We conducted a survey of female flight attendants who were pregnant at any time between January 1, 1990, and December 31, 1991 (n = 418) using a mailed self-administered interest survey (response rate, 60 %) and follow-up questionnaire regarding reproductive outcomes and potential risk factors for adverse outcomes (response rate, 64%). The cumulative hazard of spontaneous abortion was 17% when maternal age, smoking, alcohol use, and prior spontaneous abortions were control led for, using a Cox life-table regression model. Of the female flight attendants who worked outside the home, 47 of 321 (15%) experienced a spontaneous abortion, compared with 6 of 73 (8%) who did not work outside the home during the pregnancy period (odds ratio [OR] = 1.91, 95 % confidence interval [CI] = 0.78-4.66). Flight attendants who experienced a spontaneous abortion during their first pregnancy during the study period reported working significantly more flight hours per month during their pregnancy (74 hours per month) than did flight attendants who delivered a live birth (64 hours per month) (Student's t = -3.30, P = 0.002). We conclude that although the results of this study must be considered preliminary because of the relatively low overall response rate (38%), we did not find an overall increased risk for spontaneous abortion among flight attendants, compared with other working women (10%-20%). Women who continue working as flight attendants during pregnancy and those who work relatively higher numbers of flight hours during pregnancy may, however, be at increased risk for spontaneous abortion, compared with flight attendants who do not perform such work.

Risk factors for systemic illnesses following agricultural exposures to restricted organophosphates in California, 1984-1988.

Organophosphate (OP)-related systemic illnesses reported to the Worker Health and Safety (WH&S) Branch, and restricted OP-related agricultural use data reported to the Information Services Branch at the California Department of Food and Agriculture (CDFA) (now CAL-EPA) during 1984-1988 were used to assess factors associated with OP-related systemic illnesses. Counts of OP-related systemic illnesses (numerator), relative to OP-related use data (denominator), such as pounds applied, number of applications, and acres treated (pounds applied/acres treated), were analyzed by crop treated, season of application, method of application, geographic region, and by specific OP applied. A Relative Illness/Use Ratio (RIUR) was calculated by Poisson regression. The highest risk of systemic illness was associated with OP applications to fleshy fruit (mainly fruit trees) compared to all other crops combined (RIUR = 2.9, 95%CI = 2.2-3.9) using pounds applied in the denominator, followed by vegetables and melons (RIUR = 1.9, 95%CI = 1.4-2.4). Air applications resulted in higher RIURs for systemic illness than did ground applications (RIUR = 2.1, 95%CI = 1.7-2.5). Specific OPs that showed significantly elevated RIURs for systemic illness when compared to other OPs were Mevinphos (RIUR = 5.8, 95%CI = 5.0-6.8), Demeton (RIUR = 4.3, 95%CI = 2.6-7.1), Oxydemeton-Methyl (RIUR = 3.8, 95%CI = 3.0-4.9), Methamidophos (RIUR = 1.6, 95%CI = 1.2-2.0) and Azinphos-Methyl (RIUR = 1.3, 95% CI = 1.1-1.6).

Screening for glaucomatous visual field loss with frequency-doubling perimetry.

PURPOSE: To conduct a preliminary evaluation of the efficacy of the frequency-doubling contrast test as a means of screening for glaucomatous visual field loss. METHODS: Contrast thresholds for frequency-doubled stimuli were obtained under four test conditions: superior hemifield, inferior hemifield, and central (5 degrees radius) targets using a method of adjustment (MOA); superior hemifield, inferior hemifield, and central targets using a modified binary search (MOBS); four quadrant stimuli and the central target using MOBS; and 16 stimuli (four per quadrant) and the central target using MOBS. One eye each of 36 patients with early (12), moderate (12), and advanced (12) glaucomatous visual field loss was tested, as was one eye each of 36 age-matched normal control subjects. RESULTS: For hemifield stimuli, the MOBS test procedure had better test-retest reliability, lower individual variation, and greater separation of the normal population and the population with glaucoma than did the MOA procedure. The use of progressively smaller, more localized stimuli produced successively better separation of glaucomatous and age-matched normal control eyes. Area under the Receiver Operating Characteristic curve was 0.81 for hemifield stimuli (sensitivity and specificity, 70% to 75%), 0.91 for quadrant stimuli (sensitivity and specificity, 83% to 85%), and 0.965 for the 16 stimuli (sensitivity 93%, specificity 100%). Test time was approximately 1.3 minutes for hemifields, 1.5 minutes for quadrants, and 5 minutes for the 16 targets. CONCLUSIONS: Preliminary results indicate that the frequency-doubled contrast test provides a quick, efficient means of screening for glaucomatous visual field loss. Test time is relatively short, test-retest reliability is good, and sensitivity and specificity for detection of glaucomatous visual field loss is very good. The use of the MOBS staircase procedure and small, localized stimuli result in the best performance for screening purposes. An expanded normative database and the use of more rapid suprathreshold screening strategies should enhance further the efficacy of this test.

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.

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.

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.

Laboratory methods for evaluating early pregnancy loss in an industry-based population.

Laboratory methods were adapted or developed to analyze approximately 70,000 daily urine samples collected during more than 2,500 menstrual cycles from 448 women working in the semiconductor industry. An immunoenzymometric assay (IEMA) for human chorionic gonadotropin (hCG) was employed for screening cycles in order to optimize laboratory resources and to reduce the number of samples requiring analysis by less efficient methods. The presence of hCG in urine was confirmed by the definitive immunoradiometric assay (IRMA). The screening assay eliminated 78% of cycles from further analysis because there was no evidence of conception. Thirty-eight of 448 cycles identified as having significant levels of hCG with the IEMA were confirmed as hCG positive with the IRMA. HCG-positive cycles were further evaluated by examination of daily diary data and by laboratory assays for ovarian and pituitary hormones. As a result of these evaluations, 17 of the 38 cycles identified by the IRMA as positive for hCG were found to be nonconceptive cycles. These results demonstrate the effectiveness of screening assays for hCG, as well as the importance of using multiple urinary biomarkers for the detection of early fetal loss with daily urine samples.

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.

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).

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).

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.

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.

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.

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.