Elimination of PBB-153; findings from a cohort of Michigan adults.

BACKGROUND: An industrial accident led to the widespread contamination of polybrominated biphenyl (PBB), a flame retardant, into the food system in Michigan in the 1970's. PBB continues to be detected in Michiganders' blood some forty years later. It is necessary to understand the elimination rate and half-life of PBB because it may provide clues on how to hasten the elimination of it from the human body. METHODS: Serum samples were taken from young adult and adult participants of the Michigan PBB registry from 1974 to 2019. A single compartment model was assumed for the elimination rate for PBB-153 in young adults and adults (≥16 years). Generalized linear mixed models were used to estimate the average elimination rate of PBB-153 and allowed for a random intercept and slope for the time between measurements. Models were adjusted for age at exposure, body mass index (BMI) at initial measurement, and smoking. Models were also stratified by demographic characteristics. RESULTS: In total, 1974 participants contributed 4768 samples over a forty-year span. The median initial PBB-153 level was 1.542 parts per billion (ppb) (Range: 0.001-1442.48 ppb). The adjusted median participant-specific half-life for PBB-153 was 12.23 years. The half-life of PBB-153 was lengthened by higher initial PBB level (∼1.5 years), younger age at exposure (∼5.4 years), higher BMI (∼1.0 years), and increased gravidity (∼7.3 years). Additionally, the half-life of PBB-153 was shortened by smoking status (∼-2.8 years) and breastfeeding (∼-3.5 years). CONCLUSIONS: Consistent with previous studies, PBB-153 has been demonstrated to have a long half-life in the human body and may be modified by some demographic characteristics. These updated estimates of half-life will further support evaluation of health effects associated with PBB exposure. Investigations into mechanisms to accelerate elimination and reduce body burdens of PBB-153, especially those related to body weight, are needed.

Detrimental effects of flame retardant, PBB153, exposure on sperm and future generations.

In 1973, the Velsicol Chemical Company, which manufactured FireMaster, a brominated flame retardant, and NutriMaster, a nutritional supplement, mistakenly shipped hundreds of pounds of FireMaster to grain mills around Michigan where it was incorporated into animal feed and then into the food chain across the state. An estimated 6.5 million Michigan residents consumed polybrominated biphenyl (PBB)-laced animal products leading to one of the largest agricultural accidents in U.S. history. To date, there have been no studies investigating the effects of PBB on epigenetic regulation in sperm, which could explain some of the endocrine-related health effects observed among children of PBB-exposed parents. Fusing epidemiological approaches with a novel in vitro model of human spermatogenesis, we demonstrate that exposure to PBB153, the primary component of FireMaster, alters the epigenome in human spermatogenic cells. Using our novel stem cell-based spermatogenesis model, we show that PBB153 exposure decreases DNA methylation at regulatory elements controlling imprinted genes. Furthermore, PBB153 affects DNA methylation by reducing de novo DNA methyltransferase activity at increasing PBB153 concentrations as well as reducing maintenance DNA methyltransferase activity at the lowest tested PBB153 concentration. Additionally, PBB153 exposure alters the expression of genes critical to proper human development. Taken together, these results suggest that PBB153 exposure alters the epigenome by disrupting methyltransferase activity leading to defects in imprint establishment causing altered gene expression, which could contribute to health concerns in the children of men exposed to PBB153. While this chemical is toxic to those directly exposed, the results from this study indicate that the epigenetic repercussions may be detrimental to future generations. Above all, this model may be expanded to model a multitude of environmental exposures to elucidate the effect of various chemicals on germline epigenetics and how paternal exposure may impact the health of future generations.

Biomonitoring in the Era of the Exposome.

BACKGROUND: The term "exposome" was coined in 2005 to underscore the importance of the environment to human health and to bring research efforts in line with those on the human genome. The ability to characterize environmental exposures through biomonitoring is key to exposome research efforts. OBJECTIVES: Our objectives were to describe why traditional and nontraditional (exposomic) biomonitoring are both critical in studies aiming to capture the exposome and to make recommendations on how to transition exposure research toward exposomic approaches. We describe the biomonitoring needs of exposome research and approaches and recommendations that will help fill the gaps in the current science. DISCUSSION: Traditional and exposomic biomonitoring approaches have key advantages and disadvantages for assessing exposure. Exposomic approaches differ from traditional biomonitoring methods in that they can include all exposures of potential health significance, whether from endogenous or exogenous sources. Issues of sample availability and quality, identification of unknown analytes, capture of nonpersistent chemicals, integration of methods, and statistical assessment of increasingly complex data sets remain challenges that must continue to be addressed. CONCLUSIONS: To understand the complexity of exposures faced throughout the lifespan, both traditional and nontraditional biomonitoring methods should be used. Through hybrid approaches and the integration of emerging techniques, biomonitoring strategies can be maximized in research to define the exposome.

Assessment of the feasibility and clinical value of further research to evaluate the management options for children with Down syndrome and otitis media with effusion: a feasibility study.

BACKGROUND: There is clinical uncertainty of the benefits and costs of different treatment options for children with Down syndrome who have glue ear. This study was designed to assess the extent of this lack of knowledge and determine if pursuing further information would be practical, beneficial and cost-effective. OBJECTIVES: To assess the level and practical effect of current uncertainty around treatment options for children with Down syndrome and glue ear. To assess the feasibility of studying the options for management of glue ear in children with Down syndrome via a randomised controlled trial (RCT) or multicentre prospective cohort study by evaluating the willingness of (1) parents to agree to randomisation for their children and (2) clinicians to recruit participants to a definitive study. To undertake value of information analyses to demonstrate the potential economic benefit from undertaking further research. DESIGN: A feasibility study exploring the views of parents of children with Down syndrome and professionals who have responsibility for the health and education of children with Down syndrome, on the participation in, and value of, future research into interventions for glue ear. Data were collected from parents via self-completed questionnaires, face-to-face interviews and focus groups and from professionals via online questionnaires and a Delphi review exercise. Development of economic models to represent clinical pathways of care and a RCT informed a value of information (VOI) analysis. SETTING: UK (professionals); East Midlands region of the UK (parents). PARTICIPANTS: Parents of children aged 1-11 years with Down syndrome (n = 156). Professionals including audiologists, ear, nose and throat surgeons, audiological physicians, speech and language therapists, and teachers of the deaf (n = 128). MAIN OUTCOME MEASURES: Quantitative and qualitative data on parental views and experiences of glue ear and its effects; interventions and treatment received; taking part in research and factors that would encourage or discourage participation; and the importance of various outcome domains to them and for their children. For professionals: information on caseloads; approaches to clinical management; opinions on frequency and significance of the consequences of glue ear for this population; importance of different outcome measures; opinions of interventions and their role in future research; views on health research; facilitators and barriers to recruitment, and participation in research involving RCTs. RESULTS: The complexity of the experience and individual characteristics of children with Down syndrome poses challenges for the design of any future research but these challenges were not considered by professionals to raise sufficient barriers to prevent it being undertaken. Parents were generally supportive of the need for, and value of, research but identified practical and emotional issues that would need addressing. Glue ear was considered to impact more on speech, language and communication than on hearing. Outcome measures for future research would need to evaluate these elements but measures should be designed specifically for the population. Parents and professionals identified randomisation as a significant barrier to participation. The VOI analyses identified lack of data as problematic but concluded that a future trial involving surgical intervention would be feasible at costs of < £650,000. CONCLUSIONS: Future research into the benefits of interventions for glue ear in children with Down syndrome would be feasible and could be cost-effective but should be carefully designed to facilitate and maximise participation from parents and professionals responsible for recruitment. FUNDING: The National Institute for Health Research Health Technology Assessment programme.