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Megan E. Romano Melissa N. Eliot R. Thomas Zoeller Andrew N. Hoofnagle Antonia M. Calafat Margaret R. Karagas Kimberly Yolton Aimin Chen Bruce P. Lanphear Joseph M. Braun 《International journal of hygiene and environmental health》2018,221(4):623-631
Background
Phthalates, endocrine-disrupting chemicals that are commonly found in consumer products, may adversely affect thyroid hormones, but findings from prior epidemiologic studies are inconsistent.Objectives
In a prospective cohort study, we investigated whether maternal urinary phthalate metabolite concentrations and phthalate mixtures measured during pregnancy were associated with thyroid hormones among pregnant women and newborns.Methods
We measured nine phthalate metabolites [monoethyl phthalate (MEP), mono-n-butyl phthalate, mono-isobutyl phthalate, monobenzyl phthalate (MBzP), and four monoesthers of di(2-ethylhexyl) phthalate] in urine collected at approximately 16 and 26 weeks’ gestation among women in the Health Outcomes and Measures of the Environment Study (2003–2006, Cincinnati, Ohio). Thyroid stimulating hormone (TSH) and free and total thyroxine and triiodothyronine were measured in maternal serum at 16 weeks’ gestation (n?=?202) and cord serum at delivery (n?=?276). We used multivariable linear regression to assess associations between individual urinary phthalate metabolites and concentrations of maternal or cord serum thyroid hormones. We used weighted quantile sum regression (WQS) to create a phthalate index describing combined concentrations of phthalate metabolites and to investigate associations of the phthalate index with individual thyroid hormones.Results
With each 10-fold increase in 16-week maternal urinary MEP, maternal serum total thyroxine (TT4) decreased by 0.52?μg/dL (95% CI: ?1.01, ?0.03). For each 10-fold increase in average (16- and 26-week) maternal urinary MBzP, cord serum TSH decreased by 19% (95% CI: ?33.1, ?1.9). Among mothers, the phthalate index was inversely associated with maternal serum TT4 (WQS beta?=??0.60; 95% CI: ?1.01, ?0.18). Among newborns, the phthalate index was inversely associated with both cord serum TSH (WQS beta?=??0.11; 95% CI: ?0.20, ?0.03) and TT4 (WQS beta?=??0.53; 95% CI: ?0.90, ?0.16).Conclusion
Our results suggest that co-exposure to multiple phthalates was inversely associated with certain thyroid hormones (TT4 in pregnant women and newborns, and TSH in newborns) in this birth cohort. These findings highlight the need to study chemical mixtures in environmental epidemiology. 相似文献3.
Geethapriyan Thangamani Muthuramalingam Thangaraj Khaja Moiduddin Hisham Alkhalefah Sivakumar Mahalingam Panagiotis Karmiris-Obrata&#x;ski 《Materials》2022,15(14)
Electrochemical micromachining (EMM) is a plausible method for manufacturing high accuracy and precision microscale components in a broad range of materials. EMM is commonly utilized to manufacture turbine blades for automobiles and aircrafts. In this present study, the EMM process was performed with a heat-treated copper tool electrode on aluminum 8011 alloy. The process parameters such as voltage, concentration of electrolyte, frequency, and duty factor were varied to analyze the effect of a heat-treated electrode on material removal rate (MRR), overcut, conicity, and circularity. It was observed that high MRR was obtained with lower overcut with an annealed electrode. The better conicity and circularity were obtained with a quenched electrode compared to other heat-treated and untreated tool electrodes. The artificial bee’s colony (ABC) algorithm was used to identify the optimum parameters and, finally, the confirmation test was carried out to evaluate the error difference on the machining process. The optimum combination of input process parameters found using TOPSIS and ABC algorithm for the EMM process are voltage (14 V), electrolyte concentration (30 g/L), frequency (60 Hz), and duty cycle (33%) for the annealed tool electrode and voltage (14 V), electrolyte concentration (20 g/L), frequency (70 Hz), and duty cycle (33%) for the quenched tool electrode. It was confirmed that 95% of accurate response values were proven under the optimum parameter combination. 相似文献
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