MedicalResearch.com Interview with: Dr. Jianying Hu Laboratory for Earth Surface Processes College of Urban and Environmental Sciences Peking University, Beijing People’s Republic of ChinaMedical Research: What is the background for this study? What are the main findings? Response: Early pregnancy loss or first-trimester miscarriage is the most common complication of human reproduction, and the miscarriage incidence is increasing around the world in the recent decades. Though there are many causes for miscarriage, approximately 40% of early pregnancy loss remains unexplained. Exposure to endocrine disrupting chemicals (EDCs) has been considering one of major risk factor to affect female reproduction. Of these EDCs related to reproductive toxicity, phthalates is of concern due to their wide usage and contamination in environment, and the reproductive toxicity in the female mouse. Our study found that the levels of phthalates in the women who underwent miscarriage were statistically significantly high, and the risk of clinical pregnancy loss was associated with urinary concentration of phthalate metabolites. (more…)
MedicalResearch.com Interview with: Teresa M. Attina, MD, PhD, MPH and Leonardo Trasande, MD, MPP Department of Pediatrics NYU Langone Medical Center Medical Research: What is the background for this study?Response: Phthalates are environmental chemicals widely used in consumer and personal care products, and often found in plastic to increase flexibility. Di-2-ethylhexylphthalate (DEHP) is of particular interest because industrial processes to produce food frequently use plastic products containing DEHP. Because recognition of potential health risks related to DEHP exposure has increased, DEHP is being replaced by di-isononyl phthalate (DINP) and di-isodecyl phthalate (DIDP), two phthalates with similar chemical properties. Specifically, DINP is used in plastic products for food packaging, and DIDP is used in furnishings, cookware, medications, and several other consumer products. These alternatives have not been substantially studied for toxicity in laboratory studies because these studies are not required for regulatory approval: unlike the EU, in the US the current regulatory framework assumes that chemicals are safe until proven toxic. Medical Research: What are the main findings?Response: We examined DINP and DIDP levels in urine samples from children and adolescents (6 to 19 years old) who participated in the National Health and Nutrition Examination Survey between 2009 and 2012, to assess if these levels were associated with blood pressure measurements. Diet, physical activity, gender, race/ethnicity, income, and other factors that can contribute to increased blood pressure were also included in the analysis. A significant association was found between high blood pressure and DINP/DIDP levels in study participants. This is not a cause-and-effect relationship but it suggests that phthalates may contribute to increased blood pressure. (more…)
MedicalResearch.com Interview with: Dr. Jennifer Adibi, MPH ScD University of Pittsburgh, Public HealthAssistant Professor, Epidemiology Assistant Professor, Department of Obstetrics/Gynecology and Reproductive Sciences Affiliate, Dept. of ObGYN and Reproductive Sciences University of California, San Francisco Medical Research: What is the background for this study? Dr. Adibi: Prenatal exposure to phthalates in rodents can cause defects in male sexual development including a shorter distance between the anus and the genitalia (anogenital distance or AGD). Human studies have shown a correlation between higher prenatal phthalate urinary concentrations in the mother and shorter AGD in males. AGD in males is related to fertility and reproductive health over the lifetime. In females, AGD was associated with numbers of ovarian follicles. The role of the placenta has not been considered in these studies. A placental hormone called human chorionic gonadotropin (hCG) is essential for normal male development. Our previous research has shown that hCG expression by human placental cells is disrupted by phthalate concentrations equal to what we measured in maternal urine. The placenta secretes molecules early in pregnancy that might provide an opportunity to detect these effects in humans. Medical Research: What are the main findings?Dr. Adibi: In 350 pregnancies, we measured a significant association of maternal urinary concentrations of mono-n-butyl phthalate (MnBP) and monobenzyl phthalate (MBzP) with hCG in maternal blood in the first trimester. Higher phthalate concentrations were associated with higher hCG if the mother was carrying a female fetus, and lower concentrations if she was carrying a male fetus. In a high/low MnBP comparison, hCG was 15-fold higher in the higher exposed female fetuses. We also observed a relationship between maternal levels of hCG in the first trimester and anogenital distance in the newborns. The correlation was positive in female newborns, and inverse in male newborns. Similar to the parent study, we observed associations of higher first trimester MnBP and mono-2-ethyl hexyl phthalate (MEHP) with lower male anogenital distance. If we combined these findings into a mediation analysis, we estimated that approximately 20-30% of the phthalate-induced effect on anogenital distance was due to the phthalate disruption of hCG. (more…)
MedicalResearch.com Interview with: Ying Xu Assistant Professor, Ph.D. Department of Civil, Architectural and Environmental Engineering University of Texas, Austin Medical Research: What is the background for this study? What are the main findings? Response: Phthalates have been widely used as plasticizers to enhance the flexibility of polyvinyl chloride (PVC) products. They are ubiquitous and persistent indoor pollutants and may result in profound and irreversible changes in the development of human reproductive tract. In this study, we found that the emissions of phthalates and phthalate alternatives increase significantly with increasing temperature. We developed an emission model and validated the model via chamber experiments. Further analysis showed that, in infant sleep microenvironments, an increase in the temperature of mattress can cause a significant increase in emission of phthalates from the mattress cover and make the concentration in breathing zone about four times higher than that in the room, resulting in potentially high exposure. In residential homes, an increase in the temperature from 25 to 35 ºC can elevate the gas-phase concentration of phthalates by more than a factor of 10, but the total airborne concentration may not increase that much for less volatile compounds. (more…)
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