Twin and family studies reveal strong environmental and weaker genetic cues explaining heritability of eosinophilic esophagitis.

BACKGROUND: Eosinophilic esophagitis (EoE) is a chronic antigen-driven allergic inflammatory disease, likely involving the interplay of genetic and environmental factors, yet their respective contributions to heritability are unknown. OBJECTIVE: To quantify the risk associated with genes and environment on familial clustering of EoE. METHODS: Family history was obtained from a hospital-based cohort of 914 EoE probands (n = 2192 first-degree "Nuclear-Family" relatives) and an international registry of monozygotic and dizygotic twins/triplets (n = 63 EoE "Twins" probands). Frequencies, recurrence risk ratios (RRRs), heritability, and twin concordance were estimated. Environmental exposures were preliminarily examined. RESULTS: Analysis of the Nuclear-Family-based cohort revealed that the rate of EoE, in first-degree relatives of a proband, was 1.8% (unadjusted) and 2.3% (sex-adjusted). RRRs ranged from 10 to 64, depending on the family relationship, and were higher in brothers (64.0; P = .04), fathers (42.9; P = .004), and males (50.7; P < .001) than in sisters, mothers, and females, respectively. The risk of EoE for other siblings was 2.4%. In the Nuclear-Family cohort, combined gene and common environment heritability was 72.0% ± 2.7% (P < .001). In the Twins cohort, genetic heritability was 14.5% ± 4.0% (P < .001), and common family environment contributed 81.0% ± 4% (P < .001) to phenotypic variance. Probandwise concordance in monozygotic co-twins was 57.9% ± 9.5% compared with 36.4% ± 9.3% in dizygotic co-twins (P = .11). Greater birth weight difference between twins (P = .01), breast-feeding (P = .15), and fall birth season (P = .02) were associated with twin discordance in disease status. CONCLUSIONS: EoE RRRs are increased 10- to 64-fold compared with the general population. EoE in relatives is 1.8% to 2.4%, depending on relationship and sex. Nuclear-Family heritability appeared to be high (72.0%). However, the Twins cohort analysis revealed a powerful role for common environment (81.0%) compared with additive genetic heritability (14.5%).

Adolescents' and young women's use of a microbicide surrogate product when receiving oral sex.

STUDY OBJECTIVE: Genital herpes, which can be spread through oral sex, is an important target for microbicides. We examined episode-specific predictors of young women's receptive oral sex and of microbicide surrogate use. DESIGN: Longitudinal study. SETTING: Participants were recruited to participate in a microbicide acceptability study from adolescent clinics and local colleges and through snowballing. PARTICIPANTS: Young women (ages 14 to 21 y) who reported sexual contact on at least 1 weekly phone interview (n = 181) were included from the larger sample of 208 young women. MAIN OUTCOME MEASURES: On weekly diary phone interviews, participants reported whether or not their last sexual contact included receptive oral sex and whether or not their last sexual contact included use of a microbicide surrogate. RESULTS AND CONCLUSIONS: Participants reported a total of 1042 episodes of sexual contact of which 311 included receptive oral sex and 354 included microbicide surrogate use. Being older, having sex for the first time with a partner, and having given oral sex were associated with having received oral sex during a sexual episode. Being older, being African American, and having discussed the microbicide surrogate with their partner were associated with having used the microbicide surrogate use during a sexual episode. These results indicate that oral sex should be considered in the design of clinical trials. Future studies need to evaluate ways to promote consistent microbicide use in the context of receiving oral sex as well as those factors (eg, taste, pleasure) which may serve as a barrier.

Publication track records as a metric of clinical research training effectiveness.

Clinical research training programs exist across the country, but no quantitative studies have been performed to evaluate the effectiveness of these programs. The goal of this study was to evaluate the success of the clinical research training program at the University of Cincinnati by comparing the publication histories of pediatric fellows who graduated from the clinical and translational research Master of Science (MS) degree programs between 1995 and 2011 with fellows who did not pursue an MS degree. Among 296 pediatric fellows, 44 of 54 graduates (81%) published at least 1 first-authored paper, as compared with 149 of 242 (62%) fellows who did not obtain an MS degree (P < 0.01). In multivariable analysis, 3-4 years after program completion, MS graduates published more papers overall (R(2) = 0.10) and more first-authored papers than did non-MS graduates (R(2) = 0.04). These findings suggest that graduate training in clinical and translational research is related to an increase in research productivity as assessed by publication rates.

Onset of breast development in a longitudinal cohort.

BACKGROUND AND OBJECTIVES: There is growing evidence of pubertal maturation occurring at earlier ages, with many studies based on cross-sectional observations. This study examined age at onset of breast development (thelarche), and the impact of BMI and race/ethnicity, in the 3 puberty study sites of the Breast Cancer and the Environment Research Program, a prospective cohort of >1200 girls. METHODS: Girls, 6 to 8 years at enrollment, were followed longitudinally at regular intervals from 2004 to 2011 in 3 geographic areas: the San Francisco Bay Area, Greater Cincinnati, and New York City. Sexual maturity assessment using Tanner staging was conducted by using standardized observation and palpation methods by trained and certified staff. Kaplan-Meier analyses were used to describe age at onset of breast maturation by covariates. RESULTS: The age at onset of breast stage 2 varied by race/ethnicity, BMI at baseline, and site. Median age at onset of breast stage 2 was 8.8, 9.3, 9.7, and 9.7 years for African American, Hispanic, white non-Hispanic, and Asian participants, respectively. Girls with greater BMI reached breast stage 2 at younger ages. Age-specific and standardized prevalence of breast maturation was contrasted to observations in 2 large cross-sectional studies conducted 10 to 20 years earlier (Pediatric Research in Office Settings and National Health and Nutrition Examination Survey III) and found to have occurred earlier among white, non-Hispanic, but not African American girls. CONCLUSIONS: We observed the onset of thelarche at younger ages than previously documented, with important differences associated with race/ethnicity and BMI, confirming and extending patterns seen previously. These findings are consistent with temporal changes in BMI.

Environmental changes to control obesity: a randomized controlled trial in manufacturing companies.

PURPOSE: To determine the effects of an environmental intervention on obesity, disease risk factors, and dietary intake in an employee population. DESIGN: Randomized controlled community trial. SETTING: Eight manufacturing companies in Kentucky with ∼150 to 350 employees each. SUBJECTS: Randomly selected employees. INTERVENTION: Multicomponent environmental intervention that included employee advisory committees, point-of-decision prompts, walking paths, cafeteria/vending changes, and educational materials. MEASURES: Height; weight; body fat; blood pressure; fasting lipids, glucose and insulin; and dietary intake were assessed prior to and 3, 6, and 12 months after initiation of the intervention. ANALYSIS: Mixed-model repeat-measure analyses of covariance were used to analyze data collected over the study period. Categorical data were analyzed in contingency tables. A p value of .05 was used to judge statistical significance. RESULTS: There were no intervention effects for outcome variables, with the exception of lower intake of saturated fat and dietary cholesterol in the intervention group compared to the control group. Over the course of the study, changes in anthropometry and biomeasures were similar in both groups. CONCLUSIONS: Findings indicate that subtle environmental changes alone may not impact employees' weight and health; however, such institutional-level approaches may be essential to support healthy lifestyle habits that are initiated by more intensive efforts. Academic researchers should continue to partner with employers and practitioners to develop, implement, and evaluate innovative health promotion strategies including environmental interventions.

Identification of maternally regulated fetal gene networks in the placenta with a novel embryo transfer system in mice.

The mechanisms for provisioning maternal resources to offspring in placental mammals involve complex interactions between maternally regulated and fetally regulated gene networks in the placenta, a tissue that is derived from the zygote and therefore of fetal origin. Here we describe a novel use of an embryo transfer system in mice to identify gene networks in the placenta that are regulated by the mother. Mouse embryos from the same strain of inbred mice were transferred into a surrogate mother either of the same strain or from a different strain, allowing maternal and fetal effects on the placenta to be separated. After correction for sex and litter size, maternal strain overrode fetal strain as the key determinant of fetal weight (P < 0.0001). Computational filtering of the placental transcriptome revealed a group of 81 genes whose expression was solely dependent on the maternal strain [P < 0.05, false discovery rate (FDR) < 0.10]. Network analysis of this group of genes yielded highest statistical significance for pathways involved in the regulation of cell growth (such as insulin-like growth factors) as well as those involved in regulating lipid metabolism [such as the low-density lipoprotein receptor-related protein 1 (LRP1), LDL, and HDL], both of which are known to play a role in fetal development. This novel technique may be generally applied to identify regulatory networks involved in maternal-fetal interaction and eventually help identify molecular targets in disorders of fetal growth.

Pubertal assessment method and baseline characteristics in a mixed longitudinal study of girls.

OBJECTIVES: The objective of this study was to describe the assessment methods and maturation status for a multisite cohort of girls at baseline recruitment and at ages 7 and 8 years. METHODS: The method for pubertal maturation staging was developed collaboratively across 3 sites. Girls at ages 6 to 8 years were recruited at 3 sites: East Harlem, New York; greater Cincinnati metropolitan area; and San Francisco Bay area, California. Baseline characteristics were obtained through interviews with caregivers and anthropometric measurements by trained examiners; breast stage 2 was defined as onset of pubertal maturation. The kappa statistic was used to evaluate agreement between master trainers and examiners. Logistic regression models were used to identify factors that are associated with pubertal maturation and linear regression models to examine factors that are associated with height velocity. RESULTS: The baseline cohort included 1239 girls. The proportion of girls who had attained breast stage 2 varied by age, race/ethnicity, BMI percentile, and site. At 7 years, 10.4% of white, 23.4% of black non-Hispanic, and 14.9% of Hispanic girls had attained breast stage>or=2; at 8 years, 18.3%, 42.9%, and 30.9%, respectively, had attained breast stage>or=2. The prime determinant of height velocity was pubertal status. CONCLUSIONS: In this multisite study, there was substantial agreement regarding pubertal staging between examiners across sites. The proportion of girls who had breast development at ages 7 and 8 years, particularly among white girls, is greater than that reported from studies of girls who were born 10 to 30 years earlier.

Longevity of the effectiveness of interim soil lead hazard control measures and influencing factors.

A 7-year follow-up was conducted to determine factors associated with the longevity of interim soil lead hazard control measures that had been applied to housing in the Cleveland OH area. The approach involved (1) visual determination of the treatment integrity, (2) collection of information regarding 14 factors that may contribute to longevity of treatment integrity and (3) collection of one composite soil sample from treated areas with visual failure at each house and another composite sample from areas without visual failure. For the 200 houses studied, an average of 4 different soil areas were treated. For 96% of these areas, the treatments used were: (1) re-seeding, (2) mulch/wood chips and (3) gravel. Of a total of 191,034 ft(2) of treated soil areas observed, less than one-third, i.e. 59,900 ft(2) (31.3%) exhibited visual failure at the time of follow-up. Hazard control method and the presence/absence of shade were the only factors found to significantly affect visual failure rates. Of the three most commonly used control measures, the lowest visual failure rate was for re-seeding, 29.1% after a mean of 7.3 years; for non-shaded areas, which had been re-seeded, the failure rate was 22.2% compared to 35.7% for shaded areas. At 116 of the 193 houses (60%) that had both visually failed and visually non-failed treated soil areas, the geometric mean soil lead concentration was higher in the failed areas (p=0.003). The actual difference was only 13% with most levels equal to or exceeding 400 ppm. However, when compared to the US EPA limit for bare soil in other residential areas (1200 ppm) the percent equal to or exceeding the limit was much higher in the visually failed areas, 33.1%, than in areas where such failure was not observed, 22.0%.

Relationship context associated with microbicide-like product use.

STUDY OBJECTIVE: Topical microbicides are being developed to provide an alternative method of prevention of HIV and sexually transmitted infections. Although topical microbicides would be a female-controlled method of prevention, their use is likely to be disclosed to partners. Thus, the characteristics of the partner relationship may play a role in their use. We sought to examine whether qualities of the relationship and of the partner were associated with using a microbicide-like product. DESIGN: We studied 166 females (14 to 21 years of age) who were participating in a 6-month study of microbicide-like products (vaginal lubricants). They described partner relationships and characteristics of the partners. RESULTS: Of the 166 participants, 118 used the product. In bivariate analyses, those whose relationships were longer, monogamous, more mutual, and more satisfying were more likely to use the product. Further, when sex occurred in the young women's or couples' homes, use also was more likely. There was no relationship between product use and whether the partner had a job or was in school or between the partners' levels of substance use. In a multivariable logistic regression with backwards elimination, only relationship satisfaction remained significant in the model. CONCLUSION: Topical microbicides will be used within the context of a relationship, and characteristics of the relationship most likely will influence use. These findings suggest that special attention may have to be given to supporting use in high-risk relationships and that all interventions to enhance uptake should consider the relationship context.

Associations between parenting behaviors and adolescent romantic relationships.

We examined associations between parenting behaviors and romantic relationship qualities in 102 adolescent girls 14-21 years of age who lived with their parent/parental figure and had current boyfriends. Adolescent girls' perceptions that parents were accepting/involved and provided appropriate strictness and supervision were significantly related to adolescent girls' perceptions of mutuality (i.e., bidirectional movement of thoughts, feelings, and activities between persons) within their own romantic relationships, which in turn was related to their romantic relationship satisfaction. No parenting variables were related to nonexclusivity.

Racial/ethnic differences in patterns of sexual behavior and STI risk among sexually experienced adolescent girls.

STUDY OBJECTIVE: Racial/ethnic differences in prevalence and patterns of oral and anal sex were analyzed among girls participating in a microbicide acceptability study. DESIGN: Cross-sectional analysis SETTING: Recruitment to participate in a 6-month study examining microbicide acceptability was conducted at a school-based health clinic and local colleges in Galveston, Texas and through snowball sampling. PARTICIPANTS: Sexually experienced girls (n = 202) ages 14 to 21 years of age. MAIN OUTCOME MEASURES: Girls reported on their demographic and sexual history at the intake interview. RESULTS AND CONCLUSIONS: Their mean age was 18.2 years; 26% were white, 43% African-American, and 31% Hispanic. African-American girls were significantly less likely than whites and Hispanics to have had oral sex; no differences were found for anal sex. African-American girls were significantly older than whites and Hispanics when they initiated oral sex. African-American girls had a greater difference between ages of vaginal and oral sex initiation than whites and Hispanics. Oral sex history was associated with a 6-factor increase and anal sex history was associated with a 3-factor increase in the likelihood of a history of sexually transmitted infection. Future studies should explore these differences in greater depth in order to develop culturally specific STI prevention efforts.

Epidemiology of necrotizing enterocolitis temporal clustering in two neonatology practices.

OBJECTIVE: To develop a statistical method for defining clusters of necrotizing enterocolitis (NEC) cases in the neonatal intensive care unit (NICU). STUDY DESIGN: The study group included 2782 infants weighing 401 to 1500 g at birth born between 1996 and 2004. NEC was defined as Bell stage II or III. Two statistical methods were used to define "disease clusters": a modified scan test and a comparison of observed and expected incidence density rates (IDRs) of NEC at each NICU. RESULTS: The proportion of infants with NEC was similar in the 2 NICUs (7.1% vs 7.7%; P = .6), as was the expected IDR of NEC (1.39/1000 patient-days vs 1.32/1000 patient-days; P = .72). Twelve temporal clusters of NEC were identified in the 2 NICUs, representing 18% of 203 total NEC cases during the study period. No seasonal/secular trends were noted for NEC rates or identified clusters. Potential NEC clusters of > or =3 cases at either NICU had a >75% likelihood of being a true NEC cluster. CONCLUSIONS: No operational definition of NEC cluster exists. This study introduces methods to use in prospective surveillance and to guide studies investigating etiologic relevance. Using the proposed methods, statistically significant clusters (ie, potential outbreaks) of NEC within NICUs can be identified early, providing an opportunity for early implementation of cluster investigation protocols.

Uptake of HPV vaccine: demographics, sexual history and values, parenting style, and vaccine attitudes.

PURPOSE: To examine the relationships of demographics, parenting, and vaccine attitudes with the acceptance of the human papillomavirus (HPV) vaccine or to the intent to vaccinate in the next 12 months. METHODS: Mothers (n = 153) with daughters ages 11 to 17 years were recruited through the pediatric clinic waiting room/announcements to complete a questionnaire. RESULTS: Eighteen percent of the daughters had not received the vaccine, although it had been offered; 34% had not been offered the vaccine and did not intend to get it in the next 12 months; 22% had not been offered the vaccine but intended to get it in the next 12 months; 26% had started vaccination or completed the series. In a multinomial, multivariable logistic regression model, those mothers who had less than a high school degree, had a history of a sexually transmitted infection, supervised their daughter more when she was with peers, and whose daughter would not mind three shots were more likely to be favorable about their daughter being vaccinated. The following variables were not related to their attitudes about getting the vaccine: mothers' and daughters' ages, race/ethnicity, mothers' self-reported history of HPV disease and age of sexual initiation, daughters' dating status and anticipated age of sexual initiation, the number of sexual topics discussed and level of comfort, mother's sexual values, and the family environment. CONCLUSIONS: Mothers' decisions about the HPV vaccine were not related to their sexual values or their daughters' sexual behavior, but rather their parenting, sense of vulnerability, and vaccine attitudes. Mothers who were not planning to vaccinate did not appear to not feel an urgency given the newness of the vaccine, and many planned to vaccinate eventually.

Adolescents' reasons for using a microbicide-like product over time.

This study examined the reasons that adolescent girls used a product over time. Adolescent girls (n = 208; 14-21 years) participated in a six-month study in which they completed three face-to-face interviews and 24-weekly phone call interviews. Participants were given microbicide-like products (vaginal lubricants) and encouraged to use them with condoms when they had intercourse. Most of the reasons for use were endorsed by most of the adolescent girls, at some time during the study. Over time, the adolescents were significantly more likely to report the following reasons for use: did not think the product would leak out (z = 2.49; P < 0.01), the product felt comfortable (z = 2.41; P < 0.02) and the product was not messy to use (z = 3.11; P < 0.01). Although it appears that adolescents are interested in microbicides, they may worry about certain characteristics of the product. It will be important to develop anticipatory guidance that focuses on the experience of using the product, making sure adolescent girls continue to use over time.

Determination of the feasibility of using a portable X-ray fluorescence (XRF) analyzer in the field for measurement of lead content of sieved soil.

Soil samples collected in housing areas with potential lead contamination generally are analyzed with flame atomic absorption spectrometry (FAAS) or other laboratory methods. Previous work indicates that field-portable X-ray fluorescence (XRF) analysis is capable of detecting soil lead levels comparable to those detected by FAAS in samples sieved to less than 125 microm in a laboratory. A considerable savings, both economical and in laboratory reporting time, would occur if a practical field method could be developed that does not require laboratory digestion and analysis. The XRF method also would provide immediate results that would facilitate the provision of information to residents and other interested parties more quickly than is possible with conventional laboratory methods. The goal of the study reported here was to determine the practicality of using the field-portable XRF analyzer for analysis of lead in soil samples that were sieved in the field. The practicality of using the XRF was determined by the amount of time it took to prepare and analyze the samples in the field and by the ease with which the procedure could be accomplished on site. Another objective of the study was to determine the effects of moisture on the process of sieving the soil. Seventy-eight samples were collected from 30 locations near 10 houses and were prepared and analyzed at the locations where they were collected. Mean soil lead concentrations by XRF were 816 ppm before drying and 817 ppm after drying, and by laboratory FAAS were 1,042 ppm. Correlation of field-portable XRF and FAAS results was excellent for samples sieved to less than 125 microm, with R2 values of .9902 and .992 before and after drying, respectively. The saturation ranged from 10 percent to 90 percent. At 65 percent saturation or higher, it was not feasible to sieve the soil in the field without a thorough drying step, since the soil would not pass through the sieve. Therefore the field method with sieving was not practical when the soil was 65 percent or more saturated unless a time-consuming drying process was included.

Microbicides: information, beliefs, and preferences for insertion.

OBJECTIVES: Microbicides are products in development to prevent sexually transmitted infection and HIV acquisition; they are not yet available to the public. We evaluated (1) where women would expect to seek information about microbicides, (2) factors that women think might affect microbicide effectiveness, and (3) women's anticipated preferences for timing and place of insertion and partner involvement. METHODS: A cross-sectional face-to-face interview was administered to women aged 18-35 years (n=126) recruited from a gynecology clinic in Galveston, Texas. Women were shown a microbicide surrogate and asked to complete a series of closed-ended questions focusing on demographics, expected sources of information on microbicides, perceived factors related to effectiveness, and preferences for timing and place of insertion and level of partner involvement. Univariate descriptive analyses were used to calculate means, medians, and frequencies. RESULTS: Women's most cited anticipated sources of information for microbicides were physicians (89%), the package insert/box (86%), and pharmacists (70%). Approximately two thirds of the women believed that menstruation or taking other medicines and approximately one third believed that taking a bath/shower before intercourse or after intercourse or using birth control medication could limit effectiveness. Women anticipated preferring to insert the microbicide before intercourse (90%) and while in the bathroom (73%). Most (95%) anticipated telling their partners they planned to use a microbicide, and 38% anticipated having their partner insert the product for them. CONCLUSIONS: Women's beliefs about those factors that could limit effectiveness of microbicides should be addressed as part of anticipatory guidance or in the package inserts. Partners likely will be involved in the use of microbicides; thus, education/marketing efforts should also incorporate partner beliefs and preferences.

Predictors of using a microbicide-like product among adolescent girls.

PURPOSE: This study examined demographic, sexual history and weekly contextual variables, and perceptions about microbicides as predictors of microbicide-like product use. METHODS: Adolescent girls (N = 208; 14-21 years) participated in a 6-month study in which they completed three face-to-face interviews and 24-weekly phone call interviews. Participants were given microbicide-like products (vaginal lubricants) and encouraged to use them with condoms when they had intercourse. RESULTS: Of the girls, 75% had had a sexual opportunity to use the product. Using multi-variable logistic regression, the following variables independently predicted ever using the product: length of sexual experience, number of lifetime vaginal partners, and the Comparison to Condoms subscale on the Perceptions of Microbicides Scale. Using a mixed model repeated measure linear regression, the following variables independently predicted frequency of use: week of the study, age, condom frequency prior to the study, and three subscales on the Perceptions of Microbicide Scale: namely, the Comparison to Condoms subscale, the Negative Effects subscale, and the Pleasure subscale. CONCLUSION: Most girls used the product, including those who were not protecting themselves with condoms. Girls' initial perceptions regarding the product predicted initial use and frequency of use. Further research should evaluate the best methods for supporting the use of these products by young or sexually less experienced girls.

Perceptions of sexual assertiveness among adolescent girls: initiation, refusal, and use of protective behaviors.

STUDY OBJECTIVE: We describe adolescent girls' perceptions of sexual assertiveness and examine the relationship of these perceptions with developmental and interpersonal variables. DESIGN: Cross-sectional analysis. SETTING: Participants were recruited from a school-based health clinic and local colleges, and through snowballing to participate in a 6-month study examining microbicide acceptability. PARTICIPANTS: 106 sexually experienced girls (ages 14 through 21 years). METHODS: Girls described their demographics, sexual history, and romantic relationships and completed the Sexual Assertiveness Scale for Women (SAS-W), which assesses perceptions of sexual assertiveness: Initiation of Sex, Refusal of Unwanted Sex, and Pregnancy-STD Prevention. RESULTS: Girls perceived themselves as asserting themselves between 50% and 75% of the time with their current or most recent partner. The Initiation subscale was not related to the other two subscales. In final models, girls with a prior pregnancy perceived themselves as initiating sex more than girls without a prior pregnancy. Having a greater number of lifetime partners was related to perceptions of less refusal, whereas greater number of partners, being sexually experienced longer, and engaging in more unprotected sex were related to perceptions of less implementation of preventive methods. None of the relationship variables were related to scores on any subscale. CONCLUSIONS: Most of these girls perceived themselves as sexually assertive. Given that sexual experience, not relationship factors, were related to perceptions of sexual assertiveness, the design of counseling messages should incorporate sexual experience. These messages should find effective ways to help girls both to communicate their sexual desires and to enhance their ability to protect themselves.

Longitudinal associations between externalizing behavior and dysfunctional eating attitudes and behaviors: a community-based study.

This study investigated longitudinal associations between externalizing behavior and dysfunctional eating attitudes and behaviors. Participants were girls drawn from the community-based Minnesota Twin Family Study and assessed at ages 11, 14, and 17. Cross-sectional correlations indicated that the strength of the associations between externalizing behavior and dysfunctional eating attitudes and behaviors increased over time. Mixed-model analyses indicated that earlier externalizing behavior predicted increases in weight preoccupation, body dissatisfaction, and use of inappropriate compensatory behaviors. Earlier use of inappropriate compensatory behaviors predicted increases in externalizing behavior.

Postural balance changes in on-duty firefighters: effect of gear and long work shifts.

OBJECTIVE: The objective of this study was to investigate the impact of long work shifts and turnout gear, including the self-contained breathing apparatus (SCBA) on firefighters' postural stability. METHODS: Sixteen firefighters were assessed using a portable forceplate system at the fire station. Postural sway parameters were recorded at the beginning of the work shift and repeated until the work shift ended. RESULTS: Task had the greatest impact on postural stability for all sway parameters. Turnout gear, with and without SCBA, improved postural stability. Postural stability decreased as firefighters spent more time on duty. CONCLUSIONS: Prolonged work shifts may be an important contributor to the high prevalence of slips and falls among firefighters. In all, the results indicate that many aspects of the firefighters' job may adversely impact their postural stability and potentially increase the risk of falling.