Occupational physical demands and menstrual cycle irregularities in flight attendants and teachers.

OBJECTIVES: Flight attendants perform physically demanding work such as lifting baggage, pushing service carts and spending the workday on their feet. We examined if more frequent exposure to occupational physical demands could explain why previous studies have found that flight attendants have a higher reported prevalence of menstrual cycle irregularities than other workers. METHODS: We conducted a cross-sectional analysis of 694 flight attendants and 120 teachers aged 18-44 years from three US cities. Eligible participants were married, had not had a hysterectomy or tubal ligation, were not using hormonal contraception and were not recently pregnant. Participants reported menstrual cycle characteristics (cramps, pain, irregular cycles, flow, bleed length, cycle length) and occupational physical demands (standing, lifting, pushing/pulling, bending/twisting, overall effort). We used modified Poisson regression to examine associations between occupation (flight attendant, teacher) and menstrual irregularities; among flight attendants, we further examined associations between occupational physical demands and menstrual irregularities. RESULTS: All occupational physical demands were more commonly reported by flight attendants than teachers. Flight attendants reported more frequent menstrual cramps than teachers, and most occupational physical demands were associated with more frequent or painful menstrual cramps. Lifting heavy loads was also associated with irregular cycles. CONCLUSIONS: Occupational physical demands were associated with more frequent and worse menstrual pain among flight attendants. The physical demands experienced by these workers may contribute to the high burden of menstrual irregularities reported by flight attendants compared with other occupational groups, such as teachers.

Chronic kidney diseases in agricultural communities: report from a workshop.

In June 2018, the National Institute of Diabetes and Digestive and Kidney Diseases and the National Institute of Environmental Health Sciences sponsored a workshop to identify research gaps in an increasingly common form of chronic kidney disease in agricultural communities, often termed "CKDu." The organizers invited a broad range of experts who provided diverse expertise and perspectives, many of whom had never addressed this particular epidemic. Discussion was focused around selected topics, including identifying and mitigating barriers to research in CKDu, creating a case definition, and defining common data elements. All hypotheses regarding etiology were entertained, and meeting participants discussed potential research strategies, choices in study design, and novel tools that may prove useful in this disease. Achievements of the workshop included robust cross-disciplinary discussion and preliminary planning of research goals and design. Specific challenges in implementing basic and clinical research and interventions in low- and middle-income countries were recognized. A balanced approach to leveraging local resources and capacity building without overreaching was emphasized.

Miscarriage among flight attendants.

BACKGROUND: Cosmic radiation and circadian disruption are potential reproductive hazards for flight attendants. METHODS: Flight attendants from 3 US airlines in 3 cities were interviewed for pregnancy histories and lifestyle, medical, and occupational covariates. We assessed cosmic radiation and circadian disruption from company records of 2 million individual flights. Using Cox regression models, we compared respondents (1) by levels of flight exposures and (2) to teachers from the same cities, to evaluate whether these exposures were associated with miscarriage. RESULTS: Of 2654 women interviewed (2273 flight attendants and 381 teachers), 958 pregnancies among 764 women met study criteria. A hypothetical pregnant flight attendant with median first-trimester exposures flew 130 hours in 53 flight segments, crossed 34 time zones, and flew 15 hours during her home-base sleep hours (10 pm-8 am), incurring 0.13 mGy absorbed dose (0.36 mSv effective dose) of cosmic radiation. About 2% of flight attendant pregnancies were likely exposed to a solar particle event, but doses varied widely. Analyses suggested that cosmic radiation exposure of 0.1 mGy or more may be associated with increased risk of miscarriage in weeks 9-13 (odds ratio = 1.7 [95% confidence interval = 0.95-3.2]). Risk of a first-trimester miscarriage with 15 hours or more of flying during home-base sleep hours was increased (1.5 [1.1-2.2]), as was risk with high physical job demands (2.5 [1.5-4.2]). Miscarriage risk was not increased among flight attendants compared with teachers. CONCLUSIONS: Miscarriage was associated with flight attendant work during sleep hours and high physical job demands and may be associated with cosmic radiation exposure.

Occupational exposures among nurses and risk of spontaneous abortion.

OBJECTIVE: We investigated self-reported occupational exposure to antineoplastic drugs, anesthetic gases, antiviral drugs, sterilizing agents (disinfectants), and X-rays and the risk of spontaneous abortion in US nurses. STUDY DESIGN: Pregnancy outcome and occupational exposures were collected retrospectively from 8461 participants of the Nurses' Health Study II. Of these, 7482 were eligible for analysis using logistic regression. RESULTS: Participants reported 6707 live births, and 775 (10%) spontaneous abortions (<20 weeks). After adjusting for age, parity, shift work, and hours worked, antineoplastic drug exposure was associated with a 2-fold increased risk of spontaneous abortion, particularly with early spontaneous abortion before the 12th week, and 3.5-fold increased risk among nulliparous women. Exposure to sterilizing agents was associated with a 2-fold increased risk of late spontaneous abortion (12-20 weeks), but not with early spontaneous abortion. CONCLUSION: This study suggests that certain occupational exposures common to nurses are related to risks of spontaneous abortion.

Rotating shift work and menstrual cycle characteristics.

BACKGROUND: Shift workers who experience sleep disturbances and exposure to light at night could be at increased risk for alterations in physiologic functions that are circadian in nature. METHODS: We investigated rotating shift work and menstrual cycle patterns in the Nurses' Health Study II using cross-sectional data collected in 1993 from 71,077 nurses aged 28-45 years who were having menstrual periods and were not using oral contraceptives. Log-binomial regression was used to estimate relative risks (RRs) and 95% confidence intervals (CIs). RESULTS: Eight percent of participants reported working rotating night shifts for 1-9 months, 4% for 10-19 months, and 7% for 20+ months during the previous 2 years. Irregular cycles (>7 days variability) were reported by 10% of participants. Seventy percent of women reported menstrual cycles of 26-31 days, 1% less than 21 days, 16% 21-25 days, 11% 32-39 days, and 1% 40+ days. Women with 20+ months of rotating shift work were more likely to have irregular cycles (adjusted RR = 1.23 [CI = 1.14-1.33]); they were also more likely to have cycle length <21 days (1.27 [0.99-1.62]) or 40+ days (1.49 [1.19-1.87]) (both compared with 26-31 days). For irregular patterns and for 40+ day cycles, there was evidence of a dose response with increasing months of rotating shift work. Moderately short (21-25 days) or long (32-39 days) cycle lengths were not associated with rotating shift work. CONCLUSIONS: Shift work was modestly associated with menstrual function, with possible implications for fertility and other cycle-related aspects of women's health.

Maternal exposure to polychlorinated biphenyls and the secondary sex ratio: an occupational cohort study.

BACKGROUND: Though commercial production of polychlorinated biphenyls was banned in the United States in 1977, exposure continues due to their environmental persistence. Several studies have examined the association between environmental polychlorinated biphenyl exposure and modulations of the secondary sex ratio, with conflicting results. OBJECTIVE: Our objective was to evaluate the association between maternal preconceptional occupational polychlorinated biphenyl exposure and the secondary sex ratio. METHODS: We examined primipara singleton births of 2595 women, who worked in three capacitor plants at least one year during the period polychlorinated biphenyls were used. Cumulative estimated maternal occupational polychlorinated biphenyl exposure at the time of the infant's conception was calculated from plant-specific job-exposure matrices. A logistic regression analysis was used to evaluate the association between maternal polychlorinated biphenyl exposure and male sex at birth (yes/no). RESULTS: Maternal body mass index at age 20, smoking status, and race did not vary between those occupationally exposed and those unexposed before the child's conception. Polychlorinated biphenyl-exposed mothers were, however, more likely to have used oral contraceptives and to have been older at the birth of their first child than non-occupationally exposed women. Among 1506 infants liveborn to polychlorinated biphenyl-exposed primiparous women, 49.8% were male; compared to 49.9% among those not exposed (n = 1089). Multivariate analyses controlling for mother's age and year of birth found no significant association between the odds of a male birth and mother's cumulative estimated polychlorinated biphenyl exposure to time of conception. CONCLUSIONS: Based on these data, we find no evidence of altered sex ratio among children born to primiparous polychlorinated biphenyl-exposed female workers.

Occupational exposure to polychlorinated biphenyls and risk of breast cancer.

BACKGROUND: Despite the endocrine system activity exhibited by polychlorinated biphenyls (PCBs), recent studies have shown little association between PCB exposure and breast cancer mortality. OBJECTIVES: To further evaluate the relation between PCB exposure and breast cancer risk, we studied incidence, a more sensitive end point than mortality, in an occupational cohort. METHODS: We followed 5,752 women employed for at least 1 year in one of three capacitor manufacturing facilities, identifying cases from questionnaires, cancer registries, and death certificates through 1998. We collected lifestyle and reproductive information via questionnaire from participants or next of kin and used semiquantitative job-exposure matrices for inhalation and dermal exposures combined. We generated standardized incidence ratios (SIRs) and standardized rate ratios and used Cox proportional hazards regression models to evaluate potential confounders and effect modifiers. RESULTS: Overall, the breast cancer SIR was 0.81 (95% confidence interval, 0.72-0.92; n = 257), and regression modeling showed little effect of employment duration or cumulative exposure. However, for the 362 women of questionnaire-identified races other than white, we observed positive, statistically significant associations with employment duration and cumulative exposure; only smoking, birth cohort, and self- or proxy questionnaire completion had statistically significant explanatory power when added to models with exposure metrics. CONCLUSIONS: We found no overall elevation in breast cancer risk after occupational exposure to PCBs. However, the exposure-related risk elevations seen among nonwhite workers, although of limited interpretability given the small number of cases, warrant further investigation, because the usual reproductive risk factors accounted for little of the increased risk.

Occupational factors and risk of preterm birth in nurses.

OBJECTIVE: We evaluated first-trimester exposures and the risk of preterm birth in the most recent pregnancy of participants of the Nurses' Health Study II. STUDY DESIGN: Log binomial regression was used to estimate the relative risk (RR) for preterm birth in relation to occupational risk factors, such as work schedule, physical factors, and exposures to chemicals and x-rays, adjusted for age and parity. RESULTS: Part-time work (

Lead exposures in U.S. Children, 2008: implications for prevention.

OBJECTIVE: We reviewed the sources of lead in the environments of U.S. children, contributions to children's blood lead levels, source elimination and control efforts, and existing federal authorities. Our context is the U.S. public health goal to eliminate pediatric elevated blood lead levels (EBLs) by 2010. DATA SOURCES: National, state, and local exposure assessments over the past half century have identified risk factors for EBLs among U.S. children, including age, race, income, age and location of housing, parental occupation, and season. DATA EXTRACTION AND SYNTHESIS: Recent national policies have greatly reduced lead exposure among U.S. children, but even very low exposure levels compromise children's later intellectual development and lifetime achievement. No threshold for these effects has been demonstrated. Although lead paint and dust may still account for up to 70% of EBLs in U.S. children, the U.S. Centers for Disease Control and Prevention estimates that >or=30% of current EBLs do not have an immediate lead paint source, and numerous studies indicate that lead exposures result from multiple sources. EBLs and even deaths have been associated with inadequately controlled sources including ethnic remedies and goods, consumer products, and food-related items such as ceramics. Lead in public drinking water and in older urban centers remain exposure sources in many areas. CONCLUSIONS: Achieving the 2010 goal requires maintaining current efforts, especially programs addressing lead paint, while developing interventions that prevent exposure before children are poisoned. It also requires active collaboration across all levels of government to identify and control all potential sources of lead exposure, as well as primary prevention.

Chromosome Translocations and Cosmic Radiation Dose in Male U.S. Commercial Airline Pilots.

BACKGROUND: Chromosome translocations are a biomarker of cumulative exposure to ionizing radiation. We examined the relation between the frequency of translocations and cosmic radiation dose in 83 male airline pilots. METHODS: Translocations were scored using fluorescence in situ hybridization chromosome painting. Cumulative radiation doses were estimated from individual flight records. Excess rate and log-linear Poisson regression models were evaluated. RESULTS: Pilots' estimated median cumulative absorbed dose was 15 mGy (range 4.5-38). No association was observed between translocation frequency and absorbed dose from all types of flying [rate ratio (RR) = 1.01 at 1 mGy, 95% confidence interval (CI) 0.97-1.04]. However, additional analyses of pilots' dose from only commercial flying suggested an association (RR = 1.04 at 1 mGy, 95% CI 0.97-1.13). DISCUSSION: Although this is the largest cytogenetic study of male commercial airline pilots to date of which the authors are aware, future studies will need additional highly exposed pilots to better assess the translocation-cosmic radiation relation.Grajewski B, Yong LC, Bertke SJ, Bhatti P, Little MP, Ramsey MJ, Tucker JD, Ward EM, Whelan EA, Sigurdson AJ, Waters MA. Chromosome translocations and cosmic radiation dose in male U.S. commercial airline pilots. Aerosp Med Hum Perform. 2018; 89(7):616-625.

Mortality and exposure response among 14,458 electrical capacitor manufacturing workers exposed to polychlorinated biphenyls (PCBs).

BACKGROUND: We expanded an existing cohort of workers (n = 2,588) considered highly exposed to polychlorinated biphenyls (PCBs) at two capacitor manufacturing plants to include all workers with at least 90 days of potential PCB exposure during 1939-1977 (n = 14,458). Causes of death of a priori interest included liver and rectal cancers, previously reported for the original cohort, and non-Hodgkin lymphoma (NHL), melanoma, and breast, brain, intestine, stomach, and prostate cancers, based on other studies. METHODS: We ascertained vital status of the workers through 1998, and cumulative PCB exposure was estimated using a new job exposure matrix. Analyses employed standardized mortality ratios (SMRs; U.S., state, and county referents) and Poisson regression modeling. RESULTS: Mortality from NHL, melanoma, and rectal, breast, and brain cancers were neither in excess nor associated with cumulative exposure. Mortality was not elevated for liver cancer [21 deaths; SMR 0.89; 95% confidence interval (CI), 0.55-1.36], but increased with cumulative exposure (trend p-value = 0.071). Among men, stomach cancer mortality was elevated (24 deaths; SMR 1.53; 95% CI, 0.98-2.28) and increased with cumulative exposure (trend p-value = 0.039). Among women, intestinal cancer mortality was elevated (67 deaths; SMR 1.31; 95% CI, 1.02-1.66), especially in higher cumulative exposure categories, but without a clear trend. Prostate cancer mortality, which was not elevated (34 deaths; SMR 1.04; 95% CI, 0.72-1.45), increased with cumulative exposure (trend p-value = 0.0001). CONCLUSIONS: This study corroborates previous studies showing increased liver cancer mortality, but we cannot clearly associate rectal, stomach, and intestinal cancers with PCB exposure. This is the first PCB cohort showing a strong exposure-response relationship for prostate cancer mortality.

Workgroup report: Implementing a national occupational reproductive research agenda--decade one and beyond.

The initial goal of occupational reproductive health research is to effectively study the many toxicants, physical agents, and biomechanical and psychosocial stressors that may constitute reproductive hazards in the workplace. Although the main objective of occupational reproductive researchers and clinicians is to prevent recognized adverse reproductive outcomes, research has expanded to include a broader spectrum of chronic health outcomes potentially affected by reproductive toxicants. To aid in achieving these goals, the National Institute for Occupational Safety and Health, along with its university, federal, industry, and labor colleagues, formed the National Occupational Research Agenda (NORA) in 1996. NORA resulted in 21 research teams, including the Reproductive Health Research Team (RHRT). In this report, we describe progress made in the last decade by the RHRT and by others in this field, including prioritizing reproductive toxicants for further study; facilitating collaboration among epidemiologists, biologists, and toxicologists; promoting quality exposure assessment in field studies and surveillance; and encouraging the design and conduct of priority occupational reproductive studies. We also describe new tools for screening reproductive toxicants and for analyzing mode of action. We recommend considering outcomes such as menopause and latent adverse effects for further study, as well as including exposures such as shift work and nanomaterials. We describe a broad domain of scholarship activities where a cohesive system of organized and aligned work activities integrates 10 years of team efforts and provides guidance for future research.

Update: cohort mortality study of workers highly exposed to polychlorinated biphenyls (PCBs) during the manufacture of electrical capacitors, 1940-1998.

BACKGROUND: The National Institute for Occupational Safety and Health previously reported mortality for a cohort of workers considered highly exposed to polychlorinated biphenyls (PCBs) between 1939 and 1977 at two electrical capacitor manufacturing plants. The current study updated vital status, examined liver and rectal cancer mortality previously reported in excess in this cohort and evaluated mortality from non-Hodgkin's lymphoma (NHL) and cancers of the stomach, intestine, breast, prostate, skin (melanoma) and brain reported to be in excess in other cohort and case-control studies of PCB-exposed persons. METHODS: Mortality was updated through 1998 for 2572 workers. Age-, gender-, race- and calendar year-adjusted standardized mortality ratios (SMRs) and 95% confidence intervals (CI) were calculated using U.S., state and county referent rates. SMRs using U.S. referent rates are reported. Duration of employment was used as a surrogate for exposure. RESULTS: Consistent with the previous follow-up, mortality from biliary passage, liver and gall bladder cancer was significantly elevated (11 deaths, SMR 2.11, CI 1.05 - 3.77), but mortality from rectal cancer was not (6 deaths, SMR 1.47, CI 0.54 - 3.21). Among women, mortality from intestinal cancer (24 deaths, SMR 1.89, CI 1.21 - 2.82) and from "other diseases of the nervous system and sense organs", which include Parkinson's disease and amyotrophic lateral sclerosis, (15 deaths, SMR 2.07, CI 1.16 - 3.42) were elevated. There were four ALS deaths, all women (SMR 4.35, CI 1.19-11.14). Mortality was elevated for myeloma (7 deaths, SMR 2.11, CI 0.84 - 4.34), particularly among workers employed 10 years or more (5 deaths, SMR 2.80, CI 0.91 - 6.54). No linear associations between mortality and duration of employment were observed for the cancers of interest. CONCLUSION: This update found that the earlier reported excess in this cohort for biliary, liver and gall bladder cancer persisted with longer follow-up. Excess mortality for intestinal cancer among women was elevated across categories of duration of employment; myeloma mortality was highest among those working 10 years or more. The small numbers of deaths from liver and intestinal cancers, myeloma and nervous system diseases coupled with the lack of an exposure-response relationship with duration of employment preclude drawing definitive conclusions regarding PCB exposure and these causes of death.

Occupational risk factors for endometriosis in a cohort of flight attendants.

OBJECTIVES: This study aimed to (i) compare odds of endometriosis in a cohort of flight attendants against a comparison group of teachers and (ii) investigate occupational risk factors for endometriosis among flight attendants. METHODS: We included 1945 flight attendants and 236 teachers aged 18-45 years. Laparoscopically confirmed endometriosis was self-reported via telephone interview, and flight records were retrieved from airlines to obtain work schedules and assess exposures for flight attendants. We used proportional odds regression to estimate adjusted odds ratios (OR adj) and 95% confidence intervals (95% CI) for associations between exposures and endometriosis, adjusting for potential confounders. RESULTS: Flight attendants and teachers were equally likely to report endometriosis (OR adj1.0, 95% CI 0.5-2.2). Among flight attendants, there were no clear trends between estimated cosmic radiation, circadian disruption, or ergonomic exposures and endometriosis. Greater number of flight segments (non-stop flights between two cities) per year was associated with endometriosis (OR adj2.2, 1.1-4.2 for highest versus lowest quartile, P trend= 0.02) but block hours (taxi plus flight time) per year was not (OR adj1.2, 95% CI 0.6-2.2 for highest versus lowest quartile, P trend=0.38). CONCLUSION: Flight attendants were no more likely than teachers to report endometriosis. Odds of endometriosis increased with number of flight segments flown per year. This suggests that some aspect of work scheduling is associated with increased risk of endometriosis, or endometriosis symptoms might affect how flight attendants schedule their flights.

Sleep Disturbance in Female Flight Attendants and Teachers.

BACKGROUND: Flight attendants (FAs) may experience circadian disruption due to travel during normal sleep hours and through multiple time zones. This study investigated whether FAs are at higher risk for sleep disturbance compared to teachers, as assessed by questionnaire, diary, and activity monitors. METHODS: Sleep/wake cycles of 45 FAs and 25 teachers were studied. For one menstrual cycle, participants wore an activity monitor and kept a daily diary. Sleep metrics included total sleep in the main sleep period (MSP), sleep efficiency (proportion of MSP spent sleeping), and nocturnal sleep fraction (proportion of sleep between 10 p.m. to 8 a.m. home time). Relationships between sleep metrics and occupation were analyzed with mixed and generalized linear models. RESULTS: Both actigraph and diary data suggest that FAs sleep longer than teachers. However, several actigraph indices of sleep disturbance indicated that FAs incurred significant impairment of sleep compared to teachers. FAs were more likely than teachers to have poor sleep efficiency [adjusted odds ratio (OR) for lowest quartile of sleep efficiency = 1.9, 95% Confidence Interval (CI) 1.2 - 3.0] and to have a smaller proportion of their sleep between 10 p.m. and 8 a.m. home time (adjusted OR for lowest quartile of nocturnal sleep fraction = 3.1, CI 1.1 -9.0). DISCUSSION: Study FAs experienced increased sleep disturbance compared to teachers, which may indicate circadian disruption. Grajewski B, Whelan EA, Nguyen MM, Kwan L, Cole RJ. Sleep disturbance in female flight attendants and teachers. Aerosp Med Hum Perform. 2016; 87(7)638-645.

Work schedule and physically demanding work in relation to menstrual function: the Nurses' Health Study 3.

OBJECTIVES: This study aimed to evaluate occupational exposures and menstrual cycle characteristics among nurses. METHODS: Using cross-sectional data collected in 2010-2012 from 6309 nurses aged 21-45 years, we investigated nurses' menstrual function in the Nurses' Health Study 3. We used multivariable regression modeling to analyze the associations between occupational exposures and prevalence of irregular cycles and long and short cycle lengths. RESULTS: The cohort reported cycle length as <21 (1.5%), 21-25 (15.6%), 26-31 (69.7%), and 32-50 (13.2%) days. In addition, 19% of participants reported irregular cycles. Working ≥41 hours/week was associated with a 16% [95% confidence interval (95% CI): 4-29%] higher prevalence of irregular cycles and a higher prevalence of very short (<21-day) cycles [prevalence odds ratio (OR) 1.93, 95% CI 1.24-3.01] in adjusted models. Irregular menstrual cycles were more prevalent among women working nights only (32% higher; 95% CI 15-51%) or rotating nights (27% higher, 95% CI 10-47%), and was associated with the number of night shifts per month (P for trend <0.0001). Rotating night schedule was associated with long (32-50 day) cycles (OR 1.28, 95% CI 1.03-1.61). Heavy lifting was associated with a higher prevalence of irregular cycles (34% higher), and the prevalence of cycles <21 days and 21-25 day cycles increased with increasing heavy lifting at work (P for trend <0.02 for each endpoint). CONCLUSION: Night work, long hours, and physically demanding work might relate to menstrual disturbances.

Reproductive factors and risk of glioma in women.

OBJECTIVE: Glioma is the most common primary malignant brain tumor in adults, responsible for 75% of adult primary malignant brain tumors, yet aside from its association with ionizing radiation, its etiology is poorly understood. Sex differences in brain tumor incidence suggest that hormonal factors may play a role in the etiology of these tumors, but few studies have examined this association in detail. The objective of this study was to explore the role of reproductive factors in the etiology of glioma in women. METHOD: As part of a population-based case-control study, histologically confirmed primary glioma cases (n = 341 women) diagnosed between January 1, 1995 and January 31, 1997 were identified through clinics and hospitals in four Midwest U.S. states. Controls (n = 527 women) were randomly selected from lists of licensed drivers and Health Care Finance Administration enrollees. In-person interviews with subjects (81%) or their proxies (19%) collected reproductive history and other exposure information. RESULTS: Glioma risk increased with older age at menarche (P for trend = 0.009) but only among postmenopausal women. Compared with women who never breast-fed, women who breast-fed >18 months over their lifetime were at increased risk of glioma (odds ratio, 1.8; 95% confidence interval, 1.1-2.9). Women who reported using hormones for symptoms of menopause had a decreased risk of glioma compared with women who never used such hormones (odds ratio, 0.7; 95% confidence interval, 0.5-1.1). CONCLUSION: These results support the hypothesis that reproductive hormones play a role in the etiology of glioma among women.

Paternal occupational exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin and birth outcomes of offspring: birth weight, preterm delivery, and birth defects.

Agent Orange is a phenoxy herbicide that was contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). We studied pregnancy outcomes among wives of male chemical workers who were highly exposed to chemicals contaminated with TCDD and among wives of nonexposed neighborhood referents. For exposed pregnancies, we estimated serum TCDD concentration at the time of conception using a pharmacokinetic model. The mean TCDD concentration for workers' births was 254 pg/g lipid (range, 3-16,340 pg/g). The mean referent concentration of 6 pg/g was assigned to pregnancies fathered by workers before exposure. A total of 1,117 live singleton births of 217 referent wives and 176 worker wives were included. Only full-term births were included in the birth weight analysis (greater than or equal to 37 weeks of gestation). Mean birth weight among full-term babies was similar among referents' babies (n = 604), preexposure workers' babies (n = 221), and exposed workers' babies (n = 292) (3,420, 3,347, and 3,442 g, respectively). Neither continuous nor categorical TCDD concentration had an effect on birth weight for term infants after adjustment for infant sex, mother's education, parity, prenatal cigarette smoking, and gestation length. An analysis to estimate potential direct exposure of the wives during periods of workers' exposure yielded a nonstatistically significant increase in infant birth weight of 130 g in the highest exposure group (TCDD concentration > 254 pg/g) compared with referents (p = 0.09). Mothers' reports of preterm delivery showed a somewhat protective association with paternal TCDD (log) concentration (odds ratio = 0.8; 95% confidence interval, 0.6-1.1). We also include descriptive information on reported birth defects. Because the estimated TCDD concentrations in this population were much higher than in other studies, the results indicate that TCDD is unlikely to increase the risk of low birth weight or preterm delivery through a paternal mechanism. Key words: birth defects, birth weight, congenital anomalies, dioxin, occupation, paternal exposure, preterm birth, TCDD.

Job stress among female flight attendants.

We evaluated the presence of chronic job stressors among flight attendants (FAs) to examine the relationships between these job stressors and psychological distress and job dissatisfaction. Seventy-three female FAs (90% participation) employed at two commercial airlines completed a detailed questionnaire. Standard questions and scale measures were used to assess job stressors, psychological distress, and job dissatisfaction. The association between job stressors and these outcomes was evaluated using multiple regression analysis. Except for fatigue, distress and job dissatisfaction were moderate to low. Job stressors were found to have a substantive effect on these outcomes, following adjustment for individual factors. Despite moderate-to-low levels of distress and dissatisfaction, targeted efforts to reduce selected job stressors and to enhance social support may be important steps toward improving the well-being and satisfaction of FAs.

Feasibility issues in reproductive biomonitoring of female flight attendants and teachers.

Flight attendants (FAs) may be at risk of adverse reproductive outcomes. We investigated the feasibility of biomonitoring studies in this mobile workforce. Forty-five female FAs and 26 female teachers (referents) collected daily urine and saliva samples for one menstrual cycle, provided daily diary data for approximately three months, and wore a wrist monitor to measure sleep disruption. A transport system enabled FAs to store samples while traveling. Overall, participation rates were low (37%) but of those recruited, over 90% of FAs and teachers completed the biomonitoring cycle. Data collection and sample integrity were not diminished by travel. Study methods resulted in good compliance and high quality data. It is possible to conduct studies of menstrual cycle function, sleep disruption, and circadian rhythm disruption in a mobile workforce potentially exposed to reproductive hazards.