Peer-reviewed publications from research funded by our program
Latest Publications
Kazemian, N., Zhou, T., Chalasani, N., Narayan, A., Cedeño Laurent, J. G., Olvera Alvarez, H. A., & Pakpour, S. (2024). Long-Term Impact of Childhood Adversity on the Gut Microbiome of Nursing Students. International journal of environmental research and public health, 21(1), 68.
This study explores how difficult experiences in childhood can affect the community of bacteria living in our guts as adults. By looking at the gut bacteria of nursing students who had tough childhoods, researchers found certain patterns: some types of bacteria were more common, while others were less so. These changes might affect how our intestines work and how we feel mentally. While we’re not sure yet if these changes directly cause mental health issues, it’s clear they’re connected. Understanding these connections could help us find better ways to support people who had tough childhoods, improving their overall health as adults.
Chemicals Exposure
2023
Young AS, Herkert N, Stapleton HM, Coull BA, Hauser R, Zoeller T, Behnisch PA, Felzel E, Brouwer A, Allen JG. Hormone receptor activities of complex mixtures of known and suspect chemicals in personal silicone wristband samplers worn in office buildings. Chemosphere. 2023 Feb;315:137705. doi: 10.1016/j.chemosphere.2022.137705. Epub 2022 Dec 30. PMID: 36592838; PMCID: PMC9937064. [Full Text]
This study aimed to investigate human exposure to complex mixtures of hormone-disrupting chemicals from various sources using silicone wristbands as passive samplers. The results demonstrated widespread hormonal activity towards estrogen, androgen, and thyroid hormone receptors in the wristbands, with women exhibiting higher exposure levels compared to men, particularly to estrogenic and anti-androgenic mixtures. The findings emphasize the significant role of personal care products and indoor environments in hormone-disrupting exposures, highlighting the contribution of chemicals that are often unidentified or poorly understood in these exposures.
2022
Schildroth S, Rodgers KM, Strynar M, McCord J, Poma G, Covaci A, Dodson RE. Per-and polyfluoroalkyl substances (PFAS) and persistent chemical mixtures in dust from U.S. colleges. Environ Res. 2022 Apr 15;206:112530. doi: 10.1016/j.envres.2021.112530. Epub 2021 Dec 11. PMID: 34902383.
This study found that persistent chemicals, including PFAS, PBDEs, PCBs, and organochlorine pesticides, are present in dust samples from U.S. college environments, with carpeting associated with PFAS concentrations and upholstered furniture associated with PBDE concentrations. The findings emphasize the importance of considering persistence when regulating chemicals, particularly those used indoors.
2021
Young AS, Herkert N, Stapleton HM, Cedeño Laurent JG, Jones ER, MacNaughton P, Coull BA, James-Todd T, Hauser R, Luna ML, Chung YS, Allen JG. Chemical contaminant exposures assessed using silicone wristbands among occupants in office buildings in the USA, UK, China, and India. Environ Int. 2021 Nov;156:106727. doi: 10.1016/j.envint.2021.106727. Epub 2021 Jul 19. PMID: 34425641; PMCID: PMC8409466. [Full Text]
This study examined the chemical exposures of office workers in different countries, highlighting significant variations in exposure levels based on country-specific regulations and usage patterns. The findings revealed ongoing exposures to banned or phased-out chemicals, as well as exposure to new substitutes, emphasizing the need for further research on the impact of these chemicals on worker health in office buildings.
2020
Kaitlin M Pearce, Imoh Okon, Christa Watson-Wright, Induction of Oxidative DNA Damage and Epithelial Mesenchymal Transitions in Small Airway Epithelial Cells Exposed to Cosmetic Aerosols, Toxicological Sciences, Volume 177, Issue 1, September 2020, Pages 248–262, https://doi.org/10.1093/toxsci/kfaa089
Research evaluated metal-containing aerosols from nano-enabled cosmetics, finding that they induced oxidative stress, DNA damage, and epithelial mesenchymal transitions (EMT) in human small airway epithelial cells, suggesting potential respiratory health risks. Compared to pristine engineered metal nanoparticles (ENPs), the aerosols exhibited significantly higher levels of oxidative stress, DNA damage, and markers of EMT, indicating that prolonged inhalation of certain nano-enabled products could lead to respiratory dysfunction.
2018
McNeely E, Staffa S.J., Mordukhovich, I., Coull B. 2018. Symptoms Related to New Flight Attendant Uniforms. BMC Public Health. 17: 972. [Full Text]
The study conducted on flight attendants revealed a higher prevalence of respiratory, dermatological, and allergic symptoms following the introduction of new uniforms, suggesting a potential link between the uniforms and health complaints. The findings indicate a relationship between the uniform change and adverse health effects in this longitudinal occupational cohort
2017
Dodson, R.E., Rodgers K.M., Carey G., Cedeno-Laurent J.G., Covaci A., Poma G., Malarvannan G., Spengler J.D., Rudel R.A., Allen J.G. 2017. Flame Retardant Chemicals in College Dormitories: Flammability Standards Influence Dust Concentrations. Environmental Science & Technology. 51(9): 4860-4869. [Full Text]
Dust samples from a variety of residential spaces in a university campus corroborate that the concentrations of flame retardants are influenced by adherence to a particular flammability standard.
Occupational Chemical Exposures
2022
Specht, A. J., Zhang, X., Young, A., Nguyen, V. T., Christiani, D. C., Ceballos, D. M., … & Weisskopf, M. G. (2022). Validation of in vivo toenail measurements of manganese and mercury using a portable X-ray fluorescence device. Journal of exposure science & environmental epidemiology, 32(3), 427-433. [Full Text]
In this study, we assessed the feasibility of using in vivo X-ray fluorescence (XRF) measurements on intact toenails as a real-time alternative to clipping and ex vivo analysis for assessing occupational exposure to manganese and mercury, demonstrating significant correlations between in vivo XRF measurements and traditional toenail clipping analysis by inductively coupled plasma mass spectrometry (ICP-MS).
Ceballos, D. M., Dong, Z., Peters, J. L., Herrick, R. F., Gupta, P., & Spengler, J. D. (2022). Metals dust in workers’ homes and potential for take home in the Greater Boston area: Pilot study. Environmental Research, 209, 112893. [Full Text]
This pilot study investigates the sources and predictors of metals in the homes of construction workers, as well as other potentially exposed workers, revealing higher concentrations of metals commonly found in construction work in the homes of construction workers compared to other workers and highlighting the importance of considering multiple metals in “take-home” exposure interventions beyond lead.
Andrew Kalweit , Eliminating Take-Home Exposures: Recognizing the Role of Occupational Health and Safety in Broader Community Health, Annals of Work Exposures and Health, Volume 64, Issue 3, April 2020, Pages 236–249, https://doi.org/10.1093/annweh/wxaa006
This review article redefines take-home exposures as a public health hazard, emphasizing the need for an ecosocial perspective, identifying structural vulnerabilities, and advocating for comprehensive prevention efforts to address chronic pathways that perpetuate health disparities among workers, their families, and communities.
Diana Ceballos , Metals and Particulates Exposure from a Mobile E-Waste Shredding Truck: A Pilot Study, Annals of Work Exposures and Health, Volume 64, Issue 8, October 2020, Pages 890–896, https://doi.org/10.1093/annweh/wxaa058
This pilot study conducted an exposure assessment on a mobile e-waste shredding truck and found high concentrations of metals and particulate matter near the shredder operator, highlighting the need for improved controls such as local exhaust ventilation and personal protective equipment to safeguard the health of workers and the environment in the US electronics recycling industry.
2021
Ceballos, D. M., Herrick, R. F., Dong, Z., Kalweit, A., Miller, M., Quinn, J., & Spengler, J. D. (2021). Factors affecting lead dust in construction workers’ homes in the Greater Boston Area. Environmental research, 195, 110510. [Full Text]
This study examined the connection between lead exposure in the homes of workers in construction and other occupations, finding higher and more variable lead dust concentrations in construction workers’ homes compared to autobody and janitor workers, indicating the potential for take-home exposure as a significant source of lead exposure in the home. These findings underscore the importance of considering work-related factors and implementing comprehensive public health interventions at the workplace, home, and community levels to address lead exposure disparities.
Ceballos, D. M., Young, A. S., Allen, J. G., Specht, A. J., Nguyen, V. T., Craig, J. A., … & Webster, T. F. (2021). Exposures in nail salons to trace elements in nail polish from impurities or pigment ingredients–A pilot study. International journal of hygiene and environmental health, 232, 113687. [Full Text]
This study examined the concentrations of trace elements in nail polishes, urine samples of nail technicians, toenail clippings, and salon surfaces, finding that while antimony levels in some nail polishes exceeded cosmetics guidelines, other metals such as aluminum, barium, iron, and nickel were present at low concentrations. The study suggests that these metals are likely derived from colorants used in nail polish and may not be major contributors to nail technician exposure, raising uncertainty about the health implications of chronic low-level metal mixtures in nail salons.
2019
Ceballos, D. M., Craig, J., Fu, X., Jia, C., Chambers, D., Chu, M. T., … & Webster, T. F. (2019). Biological and environmental exposure monitoring of volatile organic compounds among nail technicians in the Greater Boston area. Indoor Air, 29(4), 539-550. [Full Text]
This study examined the concentrations of volatile organic compounds (VOCs) in nail salons and their correlation with biomarkers in 10 nail technicians, revealing ethyl methacrylate, methyl methacrylate, toluene, and ethyl acetate as the predominant VOCs in the air. Post-shift blood samples showed significantly higher levels of toluene and ethyl acetate compared to pre-shift samples. Based on the findings in the nail salons studied, it was estimated that emissions from nail salons in the Greater Boston area may contribute to ambient VOC levels. The study highlights the importance of improving ventilation and reformulating nail products to reduce occupational VOC exposures for nail technicians.
Craig, J. A., Ceballos, D. M., Fruh, V., Petropoulos, Z. E., Allen, J. G., Calafat, A. M., … & Webster, T. F. (2019). Exposure of nail salon workers to phthalates, di (2-ethylhexyl) terephthalate, and organophosphate esters: a pilot study. Environmental science & technology, 53(24), 14630-14637.
This study investigated the exposure of nail technicians to semivolatile organic compounds (SVOCs) in nail salons, finding higher post-shift concentrations of SVOC metabolites, particularly the phthalate alternative di(2-ethylhexyl) terephthalate (DEHTP), which more than tripled from pre-shift to post-shift urine samples. DEHTP biomarkers in the study participants’ urine were higher compared to a national survey. The study suggests that nail technicians are occupationally exposed to certain phthalates, phthalate alternatives, and organophosphate esters (OPEs), with DEHTP showing the largest increase across a work day. The detection of these SVOCs on silicone wrist bands (SWBs) indicates their potential use as a tool for assessing occupational exposures in nail salon workers.
2018
Young, A. S., Allen, J. G., Kim, U. J., Seller, S., Webster, T. F., Kannan, K., & Ceballos, D. M. (2018). Phthalate and Organophosphate Plasticizers in Nail Polish: Evaluation of Labels and Ingredients. Environ. Sci. Technol. 2018, 52, 21, 12841-12850 [Full Text]
This study measured 12 phthalate and 10 organophosphate plasticizers in 40 nail polishes from 12 brands. This study highlights inconsistencies in nail polish labels and identifies TPHP and DEHP, which are potential endocrine disruptors, as ingredient substitutes for the common plasticizer DnBP.
Environmental Pollutant Exposures
2023
Valvi D, Christiani DC, Coull B, Højlund K, Nielsen F, Audouze K, Su L, Weihe P, Grandjean P. Gene-environment interactions in the associations of PFAS exposure with insulin sensitivity and beta-cell function in a Faroese cohort followed from birth to adulthood. Environ Res. 2023 Jun 1;226:115600. doi: 10.1016/j.envres.2023.115600. Epub 2023 Mar 1. PMID: 36868448; PMCID: PMC10101920. [Full Text]
This study examined the potential modification of genetic factors on the association between exposure to perfluoroalkyl substances (PFAS) and insulin sensitivity and pancreatic beta-cell function. The results indicated that certain genetic variants may interact with PFAS exposure, affecting insulin sensitivity but not beta-cell function, highlighting the importance of genetic predisposition in the PFAS-related changes in insulin sensitivity.
Goodrich JA, Walker DI, He J, Lin X, Baumert BO, Hu X, Alderete TL, Chen Z, Valvi D, Fuentes ZC, Rock S, Wang H, Berhane K, Gilliland FD, Goran MI, Jones DP, Conti DV, Chatzi L. Metabolic Signatures of Youth Exposure to Mixtures of Per- and Polyfluoroalkyl Substances: A Multi-Cohort Study. Environ Health Perspect. 2023 Feb;131(2):27005. doi: 10.1289/EHP11372. Epub 2023 Feb 22. PMID: 36821578; PMCID: PMC9945578.
This study investigated the associations between exposure to per- and polyfluoroalkyl substances (PFAS) and alterations in metabolic pathways in two independent cohorts of adolescents and young adults. The findings revealed that PFAS exposure was linked to changes in tyrosine metabolism and de novo fatty acid biosynthesis, indicating that PFAS exposure is associated with disruptions in amino acid and lipid metabolism in this population.
2022
Symanski, E., Han, H. A., Han, I., McDaniel, M., Whitworth, K. W., McCurdy, S., Cedeno Jose & James, D. (2022). Responding to natural and industrial disasters: partnerships and lessons learned. Disaster medicine and public health preparedness, 16(3), 885-888.
This research aimed to apply lessons learned from Hurricane Harvey’s disaster response to launch similar efforts after the ITC fire in Deer Park, Texas. A multidisciplinary group of academic, community, and government partners conducted various disaster research response activities. The response to Hurricane Harvey focused on improving environmental health literacy, assessing environmental contaminants, and studying the health impact of the disaster. These lessons facilitated rapid DR2 activities after the ITC fire, including air monitoring and surveys/interviews with affected residents. The study highlights the importance of academic institutions collaborating with government and community partners for effective and timely disaster response efforts, encompassing health and safety training, data collection, and research to enhance resilience.
2021
Valvi D, Højlund K, Coull BA, Nielsen F, Weihe P, Grandjean P. Life-course Exposure to Perfluoroalkyl Substances in Relation to Markers of Glucose Homeostasis in Early Adulthood. J Clin Endocrinol Metab. 2021 Jul 13;106(8):2495-2504. doi: 10.1210/clinem/dgab267. PMID: 33890111; PMCID: PMC8277200. [Full Text]
This study aimed to examine the prospective associations between life-course exposure to perfluoroalkyl substances (PFASs) and glucose homeostasis in adulthood. The results indicated that higher PFAS exposure, particularly perfluorooctane sulfonate (PFOS), was associated with decreased insulin sensitivity and increased beta-cell function, suggesting potential impacts on glucose regulation in young adults.
Nurse Engagement and Wellness Study Related Publications
2021
Olvera-Alvarez HA, Browning MHEM, Neophytou AM, Bratman GN. Associations of Residential Brownness and Greenness with Fasting Glucose in Young Healthy Adults Living in the Desert. International Journal of Environmental Research and Public Health. 2021; 18(2):520. https://doi.org/10.3390/ijerph18020520
The study found that while proximity to brownness (non-vegetated or impervious land) was not associated with fasting glucose, residential greenness was associated with decreased fasting glucose levels, indicating that green vegetation in the predominantly desert environment of El Paso may have health-promoting effects similar to other non-desert locations with higher levels of greenery.
2020
Nazif-Munoz JI., Cedeno-Laurent JG., Browning M., Spengler JD., Olvera Alvarez HA. Green, Brown, and Gray: Associations between Different Measurements of Land Patterns and Depression among Nursing Students in El Paso, Texas. International Journal of Environmental Research and Public Health, 17(21), 8146; November 4, 2020. https://doi.org/10.3390/ijerph17218146
The aim of this study was to examine the association between depression and residential greenness, brownness, and grayness among nursing students living in El Paso, Texas, which is located in an arid landscape. The findings showed that while greenness was not associated with a decrease in depression, brownness was associated with a protective effect against depression, and grayness was associated with an increased risk of depression. These results challenge previous expectations and highlight the importance of considering different land patterns in relation to mental health outcomes.
Olvera Alvarez HA., Provencio-Vasquez E., Slavich GM., Cedeno Laurent JG., McKee-Lopez G, Robbins L, Spengler J. Stress and Health in Nursing Students: The Nurse Engagement and Wellness Study. Nursing Research, Epub ahead of print, doi:10.1097/NNR.0000000000000383. August 7, 2019. [Full Text]
This study aimed to investigate the role of social, behavioral, and environmental factors in modifying the effects of stress on new nurses during their transition to hospitals. The findings showed that greater exposure to lifetime stressors was associated with an increased risk of various health conditions, while better social, environmental, behavioral, and personal profiles were associated with protective effects. These results provide valuable insights for nursing schools to develop policies and curricula that support nurses’ well-being in the healthcare environment.
2018
McKee-Lopez G, Robbins L, Provencio-Vasquez E, Olvera Alvarez HA., The Relationship of Childhood Adversity on Burnout and Depression Among BSN Students. J Professional Nursing. Available online September 22, 2018. doi.org/10.1016/j.profnurs.2018.09.008
This study aimed to examine the relationship between Adverse Childhood Experiences (ACEs) and burnout and depression levels among first semester BSN students. The results showed that a higher number of reported ACEs were associated with increased levels of burnout and severity of depressive symptoms, particularly among female students. The findings highlight the importance of educating nursing faculty about ACEs and providing early support and counseling services to students.
Virtual Exposure Assessment
2019
Yin J, Yuan J, Arfaei N, Catalano PJ, Allen JG, Spengler JD. Effects of biophilic indoor environment on stress and anxiety recovery: A between-subjects experiment in virtual reality. Environ Int. 2020 Mar;136:105427. doi: 10.1016/j.envint.2019.105427. Epub 2019 Dec 24. PMID: 31881421.
This study aimed to investigate the effects of biophilic indoor environments on stress and anxiety recovery. Using virtual reality (VR), participants were exposed to different types of biophilic design elements in virtual offices after stressor tasks. The results showed that participants in biophilic environments experienced better recovery responses in terms of reduced stress and anxiety, with immediate effects observed after exposure and varying impacts based on the specific types of biophilic elements. This research suggests that biophilic design has potential therapeutic benefits for stress reduction and that VR could be a useful tool for incorporating nature into healthcare settings.
Yin J, Arfaei N, MacNaughton P, Catalano PJ, Allen JG, Spengler JD. Effects of biophilic interventions in office on stress reaction and cognitive function: A randomized crossover study in virtual reality. Indoor Air. 2019 Nov;29(6):1028-1039. doi: 10.1111/ina.12593. Epub 2019 Sep 11. PMID: 31418925. [Full Text]
This study utilized virtual reality (VR) to investigate the effects of biophilic design on participants’ stress levels and creativity in simulated office spaces. The results showed that compared to a base case, participants in spaces with biophilic elements experienced lower physiological stress indicators and higher creativity scores. The findings suggest that biophilic interventions have the potential to reduce stress and enhance creativity, with variations based on the types of biophilic elements and the workspace type (open vs enclosed). Additionally, VR-simulated office spaces were effective in distinguishing responses to different configurations and biophilic elements.
Breast Milk and Immunotoxicity Research
2021
Kupsco A, Lee JJ, Prada D, Valvi D, Hu L, Petersen MS, Coull BA, Weihe P, Grandjean P, Baccarelli AA. Marine pollutant exposures and human milk extracellular vesicle-microRNAs in a mother-infant cohort from the Faroe Islands. Environ Int. 2022 Jan;158:106986. doi: 10.1016/j.envint.2021.106986. Epub 2021 Nov 20. PMID: 34991248; PMCID: PMC8742869.
This study found that prenatal pollutant exposures did not impact the expression of individual extracellular vesicle-derived microRNAs (EV-miRNAs). However, a sparse principal component analysis identified specific sets of EV-miRNAs associated with mercury, polychlorinated biphenyls, and perfluoroalkyl substances, suggesting potential relationships between these pollutants and miRNA expression patterns.
Kupsco A, Prada D, Valvi D, Hu L, Petersen MS, Coull B, Grandjean P, Weihe P, Baccarelli AA. Human milk extracellular vesicle miRNA expression and associations with maternal characteristics in a population-based cohort from the Faroe Islands. Sci Rep. 2021 Mar 12;11(1):5840. doi: 10.1038/s41598-021-84809-2. PMID: 33712635; PMCID: PMC7970999. [Full Text]
This study analyzed the profiles of extracellular vesicle-derived microRNAs (EV-miRNAs) in human milk from a population-based cohort. The researchers identified clusters of EV-miRNAs and found associations between their expression and factors such as the timing of milk collection post-delivery, maternal body mass index, and maternal smoking. The findings suggest that human milk EV-miRNAs may play a role in various biological processes and highlight the need for further research to understand their impact on health and disease.
Epigenetic Research
2021
Lou J, Yu S, Feng L, Guo X, Wang M, Branco AT, Li T, Lemos B. Environmentally induced ribosomal DNA (rDNA) instability in human cells and populations exposed to hexavalent chromium [Cr (VI)]. Environ Int. 2021 Aug;153:106525. doi: 10.1016/j.envint.2021.106525. Epub 2021 Mar 25. PMID: 33774497; PMCID: PMC8477438. [Full Text]
This study demonstrates that exposure to hexavalent chromium (Cr (VI)) induces instability in the ribosomal DNA (rDNA) array, leading to cycles of rapid and transient amplification and contraction of the array in human cells. The findings suggest a novel pathway of response to Cr (VI) exposure and highlight the potential influence of environmental factors and drinking habits on naturally occurring variations in rDNA copy number.
2019
Guo X, Feng L, Lemos B, Lou J. DNA methylation modifications induced by hexavalent chromium. J Environ Sci Health C Environ Carcinog Ecotoxicol Rev. 2019;37(3):133-145. doi: 10.1080/10590501.2019.1592640. Epub 2019 May 13. PMID: 31084241; PMCID: PMC8479272.
This review focuses on the impact of hexavalent chromium (Cr(Ⅵ)) exposure on DNA methylation, which is an epigenetic modification that has been implicated in Cr(Ⅵ)-induced carcinogenesis. The review highlights the effects of Cr(Ⅵ) on both global and gene-specific DNA methylation, shedding light on the mechanisms underlying the toxic and carcinogenic effects of Cr(Ⅵ) exposure.
Pulmonary Exposure Studies
2018
Watson-Wright C, Queiroz P, Rodrigues S, Donaghey TC, Brain JD, Molina RM. Repeated pulmonary exposures to zinc ions enhance inflammatory responses to subsequent metal exposures. Exp Lung Res. 2018 May-Jun;44(4-5):252-261. doi: 10.1080/01902148.2018.1517837. Epub 2018 Oct 8. PMID: 30295553; PMCID: PMC6351161.
This study investigated the effects of repeated pulmonary exposures to zinc chloride (ZnCl2) on subsequent responses to zinc or cerium exposures in rats. The findings demonstrated that prior exposure to zinc ions increased sensitivity to subsequent zinc and cerium exposures, potentially indicating enhanced sensitization and reduced antioxidant defenses.
Autism and Environmental Risk Factors
2021
Magen-Molho H, Weisskopf MG, Nevo D, Shtein A, Chen S, Broday D, Kloog I, Levine H, Pinto O, Raz R. Air Pollution and Autism Spectrum Disorder in Israel: A Negative Control Analysis. Epidemiology. 2021 Nov 1;32(6):773-780. doi: 10.1097/EDE.0000000000001407. PMID: 34347685; PMCID: PMC8478838. [Full Text]
This study aimed to evaluate the impact of residual confounding in the association between air pollution and autism spectrum disorder (ASD) by using negative control exposures. The findings indicate positive associations between postnatal exposure to certain pollutants (NOx and NO2) and gestational exposure to PM2.5-10 with ASD, suggesting a potential causal link specific to postnatal exposure to traffic-related pollution.
2017
Raz R., Levine H., Pinto O., Broday D.M., Yuval, Weisskopf M.G. Traffic-Related Air Pollution and Autism Spectrum Disorder: A Population-Based Nested Case-Control Study in Israel. Am. J. Epidemiol. 187.4 (2017): 717-725. [Full Text]
This study assessed the association between nitrogen dioxide, a traffic pollution tracer, and risk of ASD. The findings suggest that postnatal exposure to nitrogen dioxide in Israel is associated with increased odds of ASD, and prenatal exposure with lower odds. The latter may relate to selection effects.
2018
Rotem, R.S., Chodick G., Davidovitch M., Hauser R., Coull B.A., Weisskopf M.G. Congenital Abnormalities of the Male Reproductive System and Risk of Autism Spectrum Disorders. Am. J. Epidemiol. 187.4 (2018): 656-663. [Full Text]
Androgens have an extensive influence on brain development in regions of the brain that are relevant for autism spectrum disorder (ASD), yet their etiological involvement remains unclear. In this study, ASD risk was not found to be elevated among unaffected brothers of hypospadias or cryptorchidism cases, providing some indication for the possibility of pregnancy-specific risk factors driving the observed associations.