Association between exposures to phthalate metabolites and preterm birth and spontaneous preterm birth: A systematic review and meta-analysis.

Emerging evidence from observational studies proves the association between preterm birth (PTB) and phthalate metabolites; however, such findings are inconsistent and inconclusive. This meta-analysis aimed to clarify this association by accessing the connection between 11 phthalate metabolites and PTB, and 6 phthalate metabolites and spontaneous PTB. The PubMed, Embase, and WOS (Web of Science) databases were searched up to July 2020. Seven prospective studies met the inclusion criteria. Pooled odds ratios (OR) with 95 % confidence intervals (CIs) were calculated for risk estimation. Our results indicated that mono-n-butyl phthalate (MBP), sum of di-2-ethylhexyl phthalate (ΣDEHP), and mono 3-carboxypropyl phthalate (MCPP) significantly correlated with the risk of PTB (MBP: OR = 1.23, 95 % CI = 1.05-1.45; ΣDEHP: OR = 1.21, 95 % CI =1.01-1.44; MCPP: OR = 1.09, 95 % CI = 1.00-1.19). Pooled results showed that spontaneous PTB was associated with higher urinary levels of mono-ethyl phthalate (MEP), MCPP, mono-isobutyl phthalate (MIBP), and MBP (MBP: OR = 1.27, 95 % CI = 1.02-1.58; MEP: OR = 1.19, 95 % CI = 1.01-1.40; MCPP: OR = 1.15, 95 % CI = 1.02-1.30; MIBP: OR = 1.38, 95 % CI = 1.12-1.71). Overall, we conclude that during pregnancy, MBP, ΣDEHP, and MCPP levels are associated positively with PTB. MBP, MEP, MCPP, and MIBP levels had increased odds of spontaneous PTB. No significant associations were observed between other phthalate metabolites and PTB or spontaneous PTB. Further research is needed to verify these findings and elucidate the association of phthalate levels and PTB.

The associations between exposure to trihalomethanes during pregnancy and adverse birth outcomes: A systematic review and meta-analysis.

The study aimed to examine the associations between the level of trihalomethanes and its metabolites in pregnancy and the risks of adverse birth outcomes. We searched the databases of the China National Knowledge Infrastructure, WanFang, Vip, PubMed, and Elsevier Science Direct from database establishment to July 14, 2021 and performed a systematic review and meta-analysis of observational studies reporting associations between trihalomethanes level and abnormally low birth weight and preterm birth. The pooled odds ratio (OR), pooled risk ratio, and pooled risk difference with their 95% confidence interval (CI) were calculated for risk estimates. A total of 24 studies involving 1,118,037 pregnant women were finally enrolled in the present systematic review and meta-analysis. Our research found that abnormally low birth weight was associated with higher levels of total trihalomethanes (OR = 2.45, 95% CI: 1.28, 4.68; P = 0.007). Unexpectedly, the meta-analysis indicated that higher total trihalomethanes level was associated with lower odds of preterm birth (OR = 0.90, 95% CI: 0.81, 0.99; P = 0.03). Our findings indicate that trihalomethanes exposure might be a risk factor for abnormally low birth weight and that it would be prudent to minimize exposure to trihalomethanes during pregnancy because of the risk of abnormally low birth weight. Given some limitations of the systematic review and meta-analysis, our results should be interpreted with caution.

Associations between both legacy and alternative per- and polyfluoroalkyl substances and glucose-homeostasis: The Isomers of C8 health project in China.

BACKGROUND: Epidemiological studies on the associations of legacy per- and polyfluoroalkyl substances (PFASs) and glucose homeostasis remain discordant. Understanding of PFAS alternatives is limited, and few studies have reported joint associations of PFASs and PFAS alternatives. OBJECTIVES: To investigate associations of novel PFAS alternatives (chlorinated perfluoroalkyl ether sulfonic acids, Cl-PFESAs and perfluorobutanoic acid, PFBA) and two legacy PFASs (Perfluorooctanoic acid, PFOA and perfluorooctane sulfonate, PFOS) with glucose-homeostasis markers and explore joint associations of 13 legacy and alternative PFASs with the selected outcomes. METHODS: We used cross-sectional data of 1,038 adults from the Isomers of C8 Health Project in China. Associations of PFASs and PFAS alternatives with glucose-homeostasis were explored in single-pollutant models using generalized linear models with natural cubic splines for PFASs. Bayesian Kernel Machine Regression (BKMR) models were applied to assess joint associations of exposures and outcomes. Sex-specific analyses were also conducted to evaluate effect modification. RESULTS: After adjusting for confounders, both legacy (PFOA, PFOS) and alternative (Cl-PFESAs and PFBA) PFASs were positively associated with glucose-homeostasis markers in single-pollutant models. For example, in the total study population, estimated changes with 95% confidence intervals (CI) of fasting glucose at the 95th percentile of 6:2Cl-PFESA and PFOS against the thresholds were 0.90 (95% CI: 0.59, 1.21) and 0.44 (95% CI: 0.26, 0.62). Positive joint associations were found in BKMR models with 6:2Cl-PFESA contributing most. Sex-specific associations existed in both single- and multi-pollutant models. CONCLUSIONS: Legacy and alternative PFASs were positively associated with glucose-homeostasis markers. 6:2Cl-PFESA was the primary contributor. Sex-specific associations were also identified. These results indicate that joint associations and effect modification should be considered in risk assessment. However, further studies are recommended to strengthen our findings and to elucidate the mechanisms of action of legacy and alternative PFASs.

Exposure to second-hand smoke during early life and subsequent sleep problems in children: a population-based cross-sectional study.

BACKGROUND: Previous studies have revealed that current secondhand smoke exposure showed highly suggestive evidence for increased risk of simultaneous sleep problems in children. Data on the associations between early-life exposure to SHS with subsequent sleep problems in children were scarce. We aimed to evaluate the associations of early-life SHS exposure with sleep problems in children. METHODS: In this cross-sectional study, children were recruited from elementary and middle schools in Liaoning Province, China between April 2012 and January 2013. We assessed early-life SHS exposure (pregnancy and the first 2 years of life) via questionnaires. Sleep problems and different types of sleep-related symptoms were measured based on the validated tool of the Sleep Disturbance Scale for Children (SDSC). Generalized linear mixed models were applied to estimate the associations of early-life SHS exposure with sleep problems. RESULTS: We included a total of 45,562 children (22,657 [49.7%] males; mean [SD] age, 11.0 [2.6] years) and 6167 of them (13.5%) were exposed to early-life SHS during both pregnancy and the first 2 years of life. Compared with unexposed counterparts, children exposed to early-life SHS had higher total T-scores of SDSC (ß = 4.32; 95%CI: 4.06, 4.58) and higher odds of increased sleep problems (OR = 2.14; 95%CI: 1.89, 2.42). When considering different sleep-related symptoms, the associations between early-life SHS exposure and symptom of sleep-wake transition disorders (i.e., bruxism) were the strongest in all analyses. CONCLUSIONS: Early-life SHS exposure was associated with higher odds of global sleep problems and different sleep-related symptoms in children aged 6-18 years. Our findings highlight the importance to strengthen efforts to support the critical importance of maintaining a smoke-free environment especially in early life.

[Correlation of serum androgen levels with lipid metabolism in middle-aged and elderly men in Zunyi, Guizhou].

OBJECTIVE: To investigate the relationship of the levels of serum androgens with lipid metabolism in middle-aged and elderly men in Zunyi, Guizhou. METHODS: Using the stratified cluster sampling method, we conducted a questionnaire investigation and physical examinations among 437 men in Zunyi City. We divided the subjects into a middle-aged (40－64 ï¼»53.20 ± 7.41ï¼½ years, n = 269) and an elderly group (=≥65 ï¼»70.63 ± 4.66ï¼½ years, n = 168) and collected fasting elbow venous blood samples from them for measuring the levels of total testosterone (TT), sex hormone-binding globulin (SHBG), luteinizing hormone (LH), total cholesterol (TCH), triglyceride (TG), high-density lipoprotein (HDL), low-density lipoprotein (LDL), calculated free testosterone (cFT), free testosterone index (FTI), and testosterone secretion index (TSI). RESULTS: Compared with the elderly group, the middle-aged males showed significantly lower SHBG, LH, HDL and LDL, and higher cFT, FTI, TSI, TG and TCH (all P < 0.05). TT and SHBG were negatively correlated with TG, TCH, HDL and LDL, while cFT was positively correlated with TCH, and so was FTI with TG, TCH with LDL, and TSI with TCH, HDL and LDL (all P < 0.05), but LH was negatively correlated with TG, TCH and LDL (all P < 0.05). Multivariate linear regression analysis showed that TT and SHBG were negatively correlated with TG, TCH, HDL and LDL, and so was LH with TCH, HDL and LDL (all P < 0.05). CONCLUSIONS: In the middle-aged and elderly men in Zunyi, low concentrations of TT, SHBG and LH were associated with the increased risk of high-TCH and -LDL dyslipidemia, low concentrations of TT and SHBG with that of high-TG dyslipidemia, while high concentrations of TT, SHBG and LH with that of low-HDL dyslipidemia.

[Vasectomy has no obvious longterm influence on the levels of serum androgens in aging males].

OBJECTIVE: To explore the longterm influence of vasectomy on the levels of serum androgens in aging males. METHODS: Using stratified random sampling, we conducted a questionnaire survey and physical examinations among 437 adult males aged ≥40 years, 232 with and 205 without the history of vasectomy. In addition, we measured the levels of serum total testosterone (TT), sexhormone binding globulin (SHBG), calculated free testosterone (cFT), testosterone secreting index (TSI), free testosterone index (FTI), and luteinizing hormone (LH). RESULTS: Compared with the nonvasectomy group, the vasectomy group showed significantly increased levels of serum TT (ï¼»16.01±5.41ï¼½ vs ï¼»17.39±6.57ï¼½ nmol/L), SHBG (ï¼»58.91±36.89ï¼½ vs ï¼»70.28±40.90ï¼½ nmol/L), and LH (ï¼»8.86±6.49ï¼½ vs ï¼»10.85±11.73ï¼½ IU/L) (all P< 0.05) and a decreased level of FTI (0.33±0.15 vs 0.30±0.12, P< 0.05). There were no statistically significant differences between the nonvasectomy and vasectomy groups in cFT (ï¼»0.24±0.07ï¼½ vs ï¼»0.23±0.09ï¼½ nmol/L) or TSI (ï¼»2.42±1.34ï¼½ vs ï¼»2.46±1.51ï¼½ nmol/IU) (both P>0.05), nor after adjustment for relevant factors in TT (ß: 1.015, 95% CI: －0.180－2.210), SHBG (ß: 5.118, 95% CI: －2.069－12.305), cFT (ß: 0.003, 95% CI: －0.011－0.018), FTI (ß: －0.012, 95% CI: －0.035－0.011), TSI (ß: 0.138, 95% CI: －0.131－0.407), and LH (ß: 1.011, 95% CI: －0.811－2.834) (all P>0.05). CONCLUSIONS: Vasectomy has no obvious longterm influence on the levels of serum androgens in aging males.