Last data update: Apr 29, 2024. (Total: 46658 publications since 2009)
Records 1-18 (of 18 Records) |
Query Trace: Whelan E[original query] |
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Occupational physical demands and menstrual cycle irregularities in flight attendants and teachers
Johnson CY , Grajewski B , Lawson CC , MacDonald LA , Rocheleau CM , Whelan EA . Occup Environ Med 2024 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. |
Defining the risk of SARS-CoV-2 variants on immune protection.
DeGrace MM , Ghedin E , Frieman MB , Krammer F , Grifoni A , Alisoltani A , Alter G , Amara RR , Baric RS , Barouch DH , Bloom JD , Bloyet LM , Bonenfant G , Boon ACM , Boritz EA , Bratt DL , Bricker TL , Brown L , Buchser WJ , Carreo JM , Cohen-Lavi L , Darling TL , Davis-Gardner ME , Dearlove BL , Di H , Dittmann M , Doria-Rose NA , Douek DC , Drosten C , Edara VV , Ellebedy A , Fabrizio TP , Ferrari G , Florence WC , Fouchier RAM , Franks J , Garca-Sastre A , Godzik A , Gonzalez-Reiche AS , Gordon A , Haagmans BL , Halfmann PJ , Ho DD , Holbrook MR , Huang Y , James SL , Jaroszewski L , Jeevan T , Johnson RM , Jones TC , Joshi A , Kawaoka Y , Kercher L , Koopmans MPG , Korber B , Koren E , Koup RA , LeGresley EB , Lemieux JE , Liebeskind MJ , Liu Z , Livingston B , Logue JP , Luo Y , McDermott AB , McElrath MJ , Meliopoulos VA , Menachery VD , Montefiori DC , Mhlemann B , Munster VJ , Munt JE , Nair MS , Netzl A , Niewiadomska AM , O'Dell S , Pekosz A , Perlman S , Pontelli MC , Rockx B , Rolland M , Rothlauf PW , Sacharen S , Scheuermann RH , Schmidt SD , Schotsaert M , Schultz-Cherry S , Seder RA , Sedova M , Sette A , Shabman RS , Shen X , Shi PY , Shukla M , Simon V , Stumpf S , Sullivan NJ , Thackray LB , Theiler J , Thomas PG , Trifkovic S , Treli S , Turner SA , Vakaki MA , vanBakel H , VanBlargan LA , Vincent LR , Wallace ZS , Wang L , Wang M , Wang P , Wang W , Weaver SC , Webby RJ , Weiss CD , Wentworth DE , Weston SM , Whelan SPJ , Whitener BM , Wilks SH , Xie X , Ying B , Yoon H , Zhou B , Hertz T , Smith DJ , Diamond MS , Post DJ , Suthar MS . Nature 2022 605 (7911) 640-652 The global emergence of many severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants jeopardizes the protective antiviral immunity induced following infection or vaccination. To address the public health threat caused by the increasing SARS-CoV-2 genomic diversity, the National Institute of Allergy and Infectious Diseases (NIAID) within the National Institutes of Health (NIH) established the SARS-CoV-2 Assessment of Viral Evolution (SAVE) program. This effort was designed to provide a real-time risk assessment of SARS-CoV-2 variants potentially impacting transmission, virulence, and resistance to convalescent and vaccine-induced immunity. The SAVE program serves as a critical data-generating component of the United States Government SARS-CoV-2 Interagency Group to assess implications of SARS-CoV-2 variants on diagnostics, vaccines, and therapeutics and for communicating public health risk. Here we describe the coordinated approach used to identify and curate data about emerging variants, their impact on immunity, and effects on vaccine protection using animal models. We report the development of reagents, methodologies, models, and pivotal findings facilitated by this collaborative approach and identify future challenges. This program serves as a template for the response against rapidly evolving pandemic pathogens by monitoring viral evolution in the human population to identify variants that could erode the effectiveness of countermeasures. |
Flea presence and abundance are not predictors of Bartonella tribocorum carriage in Norway rats (Rattus norvegicus) from an underserved neighborhood of Vancouver, Canada
Himsworth CG , Byers KA , Whelan T , Bai Y , Kosoy MY . Vector Borne Zoonotic Dis 2020 21 (2) 121-124 Urban Norway rats (Rattus norvegicus) carry pathogenic Bartonella spp. that are transmitted among rats and from rats to people through arthropod vectors, particularly fleas. There is marked temporospatial variation in Bartonella spp. carriage among Norway rats in Vancouver, Canada, and we investigated whether this variation is associated with flea presence or abundance. Bartonella triborocum was isolated from 96/370 (35%) rats and 211 (57%) rats had fleas with an average of one flea per rat. All fleas were identified as Nosopsyllus fasciatus. There was no significant relationship between B. tribocorum carriage and flea presence or abundance, suggesting that, in contrast to other rat-associated zoonoses transmitted by fleas (e.g., Yersinia pestis) flea indices may not be informative for understanding the ecology of Bartonella spp. in rats, particularly for N. fasciatus. |
Chronic kidney diseases in agricultural communities: report from a workshop
Mendley SR , Levin A , Correa-Rotter R , Joubert BR , Whelan EA , Curwin B , Koritzinsky EH , Gaughan DM , Kimmel PL , Anand S , Ordunez P , Reveiz L , Rohlman DS , Scammell MK , Wright RO , Star RA . Kidney Int 2019 96 (5) 1071-1076 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. |
Effects of inflammation on biomarkers of vitamin A status among a cohort of Bolivian infants
Burke RM , Whitehead RDJr , Figueroa J , Whelan D , Aceituno AM , Rebolledo PA , Revollo R , Leon JS , Suchdev PS . Nutrients 2018 10 (9) Globally, vitamin A deficiency (VAD) affects nearly 200 million children with negative health consequences. VAD can be measured by a retinol-binding protein (RBP) and serum retinol concentrations. Their concentrations are not always present in a 1:1 molar ratio and are affected by inflammation. This study sought to quantify VAD and its impact on infant mortality and infectious morbidity during the first 18 months of life in a cohort of mother-infant dyads in El Alto, Bolivia, while accounting for the previously mentioned measurement issues. Healthy mother-infant dyads (n = 461) were enrolled from two hospitals and followed for 12 to 18 months. Three serum samples were collected (at one to two, six to eight, and 12 to 18 months of infant age) and analyzed for RBP, and a random 10% subsample was analyzed for retinol. Linear regression of RBP on retinol was used to generate RBP cut-offs equivalent to retinol <0.7 micromol/L. All measures of RBP and retinol were adjusted for inflammation, which was measured by a C-reactive protein and alpha (1)-acid glycoprotein serum concentrations using linear regression. Infant mortality and morbidity rates were calculated and compared by early VAD status at two months of age. Retinol and RBP were weakly affected by inflammation. This association varied with infant age. Estimated VAD (RBP < 0.7 micromol/L) decreased from 71.0% to 14.8% to 7.7% at two, six to eight, and 12 to 18 months of age. VAD was almost nonexistent in mothers. Early VAD was not significantly associated with infant mortality or morbidity rates. This study confirmed a relationship between inflammation and vitamin A biomarkers for some subsets of the population and suggested that the vitamin A status in early infancy improves with age and may not have significantly affected morbidity in this population of healthy infants. |
Chromosome Translocations and Cosmic Radiation Dose in Male U.S. Commercial Airline Pilots.
Grajewski B , Yong LC , Bertke SJ , Bhatti P , Little MP , Ramsey MJ , Tucker JD , Ward EM , Whelan EA , Sigurdson AJ , Waters MA . Aerosp Med Hum Perform 2018 89 (7) 616-625 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. |
Sleep disturbance in female flight attendants and teachers
Grajewski B , Whelan EA , Nguyen MM , Kwan L , Cole RJ . Aerosp Med Hum Perform 2016 87 (7) 638-45 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. |
The global epidemic of chronic kidney disease: a call for action
Whelan E . Occup Environ Med 2016 73 (8) 499-500 While the Ebola and Zika viruses have made national and international headlines in recent months, another epidemic of larger magnitude is quietly devastating agricultural communities in developing countries worldwide. In Central America, the death toll from a mysterious type of chronic kidney disease (CKD) is estimated to be 20 000 in just 10 years.1 Unlike the CKD seen in developed countries, which is typically linked to hypertension and diabetes, this disease appears to be multifactorial and disproportionately afflicts young men of working age. In El Salvador, CKD is the second leading cause of mortality among men of working age.2 Similar excesses have been reported in other parts of Central America,3 as well as in Sri Lanka,4 India5 and Egypt.6 Occupation is believed to be the driving factor. According to the leading hypothesis, heat stress and dehydration from strenuous work such as manual cutting of sugar cane, perhaps in a synergistic association with exposure to environmental toxins, result in kidney damage that leads to permanent loss of function. | Manual sugarcane cutting involves high cardiovascular demand comparable to that experienced by endurance athletes, except that cane cutters are exposed to ‘daily’ demands for the entire harvest season. The risk for the disease is exacerbated by the pay structure of the work, in that cane cutters are paid according to how much cane they cut, creating a disincentive to take breaks for rest and water. A particularly disturbing characteristic of this type of CKD is that, in its early stages, people show no symptoms. It is a silent killer. By some accounts, the disease has existed in parts of the world for decades, but the death rate has accelerated with industrial-scale agriculture expansion and global climate change. |
The Next Generation of Risk Assessment Multiyear Study- Highlights of Findings, Applications to Risk Assessment and Future Directions.
Cote I , Andersen ME , Ankley GT , Barone S , Birnbaum LS , Boekelheide K , Bois FY , Burgoon LD , Chiu WA , Crawford-Brown D , Crofton KM , DeVito M , Devlin RB , Edwards SW , Guyton KZ , Hattis D , Judson RS , Knight D , Krewski D , Lambert J , Maull EA , Mendrick D , Paoli GM , Patel CJ , Perkins EJ , Poje G , Portier CJ , Rusyn I , Schulte PA , Simeonov A , Smith MT , Thayer KA , Thomas RS , Thomas R , Tice RR , Vandenberg JJ , Villeneuve DL , Wesselkamper S , Whelan M , Whittaker C , White R , Xia M , Yauk C , Zeise L , Zhao J , DeWoskin RS . Environ Health Perspect 2016 124 (11) 1671-1682 BACKGROUND: The Next Generation (NexGen) of Risk Assessment effort is a multiyear collaboration among several organizations evaluating new, potentially more efficient molecular, computational and systems biology approaches to risk assessment. This paper summarizes our findings, suggests applications to risk assessment, and identifies strategic research directions. OBJECTIVE: Our specific objectives were to test whether advanced biological data and methods could better inform our understanding of public health risks posed by environmental exposures. METHODS: New data and methods were applied and evaluated for use in hazard identification and dose-response assessment. Biomarkers of exposure and effect, and risk characterization were also examined. Consideration was given to various decision contexts with increasing regulatory and public health impacts. Data types included transcriptomics, genomics, and proteomics; methods included molecular epidemiology and clinical studies, bioinformatic knowledge mining, pathway and network analyses, short-duration in vivo and in vitro bioassays, and quantitative structure activity relationship modeling. DISCUSSION: NexGen has advanced our ability to apply new science by more rapidly identifying chemicals and exposures of potential concern, helping characterize mechanisms of action that influence conclusions about causality, exposure-response relationships, susceptibility and cumulative risk, and by elucidating new biomarkers of exposure and effects. Additionally, NexGen has fostered extensive discussion among risk scientists and managers and improved confidence in interpreting and applying new data streams. CONCLUSIONS: While considerable uncertainties remain, thoughtful application of new knowledge to risk assessment appears reasonable for augmenting major scope assessments, forming the basis for or augmenting limited scope assessments, and for prioritization and screening of very data limited chemicals. |
Occupational risk factors for endometriosis in a cohort of flight attendants
Johnson CY , Grajewski B , Lawson CC , Whelan EA , Bertke SJ , Tseng CY . Scand J Work Environ Health 2015 42 (1) 52-60 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. |
Work schedule and physically demanding work in relation to menstrual function: the Nurses' Health Study 3
Lawson CC , Johnson CY , Chavarro JE , Lividoti Hibert EN , Whelan EA , Rocheleau CM , Grajewski B , Schernhammer ES , Rich-Edwards JW . Scand J Work Environ Health 2015 41 (2) 194-203 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. |
Miscarriage among flight attendants
Grajewski B , Whelan EA , Lawson CC , Hein MJ , Waters MA , Anderson JL , MacDonald LA , Mertens CJ , Tseng CY , Cassinelli RT 2nd , Luo L . Epidemiology 2015 26 (2) 192-203 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. |
Investing in prospective cohorts for etiologic study of occupational exposures
Blair A , Hines CJ , Thomas KW , Alavanja MC , Freeman LE , Hoppin JA , Kamel F , Lynch CF , Lubin JH , Silverman DT , Whelan E , Zahm SH , Sandler DP . Am J Ind Med 2015 58 (2) 113-22 Prospective cohorts have played a major role in understanding the contribution of diet, physical activity, medical conditions, and genes to the development of many diseases, but have not been widely used for occupational exposures. Studies in agriculture are an exception. We draw upon our experience using this design to study agricultural workers to identify conditions that might foster use of prospective cohorts to study other occupational settings. Prospective cohort studies are perceived by many as the strongest epidemiologic design. It allows updating of information on exposure and other factors, collection of biologic samples before disease diagnosis for biomarker studies, assessment of effect modification by genes, lifestyle, and other occupational exposures, and evaluation of a wide range of health outcomes. Increased use of prospective cohorts would be beneficial in identifying hazardous exposures in the workplace. Occupational epidemiologists should seek opportunities to initiate prospective cohorts to investigate high priority, occupational exposures. |
A decision process for determining whether to conduct responder health research following large disasters
Decker JA , Keifer M , Reissman DB , Funk R , Halpin J , Bernard B , Ehrenberg RL , Schuler CR , Whelan E , Myers K , Howard J . Am J Disaster Med 2013 8 (1) 25-33 Disasters often set the stage for scientific inquiry within the fieid of occupational safety and health. This is especially true when the long-term consequences of exposures associated with a particular disaster are unclear. However, a responder research study can be costly and difficult to design, and researchers must consider whether the proposed study will produce useful, reliable results and is a prudent public health investment. The decision process can be segregated into various components, including scientific rationale that should be formally recognized as critical to efficiently and effectively determine whether a research study is warranted. The scientific rationale includes certain controlling or "gatekeeper" factors that should be present to proceed with research. |
Occupational exposures among nurses and risk of spontaneous abortion
Lawson CC , Rocheleau CM , Whelan EA , Lividoti Hibert EN , Grajewski B , Spiegelman D , Rich-Edwards JW . Am J Obstet Gynecol 2011 206 (4) 327 e1-8 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. |
Shift work and adverse pregnancy outcomes: comments on a recent meta-analysis
Rocheleau C , Lawson C , Whelan E , Rich-Edwards J . BJOG 2012 119 (3) 378 Regarding the recent meta-analysis on shift work and pregnancy outcomes,1 we disagree that ‘any effects of shift work on preterm delivery are likely to be small’. These conclusions were based on a sensitivity analysis in which the authors excluded studies they deemed to be ‘of lower quality’. Some studies were excluded because shift work and preterm delivery were self-reported on the same instrument, assumed to result in recall bias. However, there is little evidence that women inaccurately report gestational age, especially in broad categories. As Gordis said: | Although a potential for recall bias is self-evident in case–control studies, in point of fact, there are few actual examples that demonstrate that recall bias has in fact been a major problem in case–control studies and has led to erroneous conclusions regarding associations.2 Items that are subjective (e.g. pain intensity), that participants pay little attention to (e.g. minor headache), or that are sensitive (e.g. illicit drugs) might be more prone to recall bias.3 Preterm birth and shift work do not meet these conditions. |
Maternal exposure to polychlorinated biphenyls and the secondary sex ratio: an occupational cohort study
Rocheleau CM , Bertke SJ , Deddens JA , Ruder AM , Lawson CC , Waters MA , Hopf NB , Riggs MA , Whelan EA . Environ Health 2011 10 (1) 20 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. |
Rotating shift work and menstrual cycle characteristics
Lawson CC , Whelan EA , Lividoti Hibert EN , Spiegelman D , Schernhammer ES , Rich-Edwards JW . Epidemiology 2011 22 (3) 305-12 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. |
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