Higher concentration of selenium in placental tissues is associated with reduced risk for orofacial clefts

A Systematic Literature Review on the Association Between Toxic and Essential Trace Elements and the Risk of Orofacial Clefts in Infants

Orofacial clefts (OFCs) have been linked to various toxic and essential trace elements (TETEs) worldwide. However, review estimation is absent. Therefore, addressing the hypothesis that TETEs are associated with OFCs is the main area of this review. A systematic literature search was conducted using electronic databases through PubMed, Web of Science, Scopus, Science Direct, and Google Scholar between 2004 and August 2022. The "AND" and "OR" operators were used to make our search results inclusive and restrictive as follows: ("Toxic element*" OR "Heavy metal*") AND ("Toxic element*" OR "Lead OR Arsenic OR Mercury*")) AND ("Essential trace element*" OR "Zinc OR Selenium OR Copper*")) AND ("Orofacial cleft*" OR "Cleft lip*" OR "Cleft palate*") AND ("Infant*" OR "Newborn*" OR "Neonate*")). The presence of toxic elements was linked to the development of OFCs. The results showed that higher levels of toxic elements in various biological sample types were related to increased risks for OFCs. Increased concentrations of essential trace elements (ETEs) lowered the risk of OFCs. Maternal consumption of diets rich in ETEs, including zinc (Zn), selenium (Se), copper (Cu), cobalt (Co), and molybdenum (Mo), was linked to a more pronounced reduction in the risk of OFCs. Based on the findings, it is acceptable to infer that maternal exposure to toxic elements, whether through environmental contaminants or dietary sources, was associated with an elevated risk of OFCs. Furthermore, the study revealed that ETEs exhibited a potential protective role in reducing the incidence of OFCs. This observation highlights the importance of reducing exposure to toxic elements during pregnancy and suggests that optimizing maternal intake of ETEs could be an effective preventive strategy.

Prenatal metal concentrations and physical abnormalities in the Japan Environment and Children's Study

BACKGROUND

The association between prenatal metal exposure and congenital anomalies is unclear. We aimed to examine the association between exposure to cadmium, lead, mercury, selenium, and manganese and physical abnormalities.

METHODS

Data from 89,887 pregnant women with singleton pregnancies who participated in the Japan Environment and Children's Study (JECS) were used. The correlation between maternal blood metal concentrations and physical abnormalities during the second or third trimester was investigated using logistic regression models. Physical anomalies included those observed at birth or at 1 month, primarily from ICD-10 Chapter 17, particularly congenital anomalies associated with environmental factors (e.g., hypospadias, cryptorchidism, cleft lip and palate, digestive tract atresia, congenital heart disease, and chromosomal abnormalities) and minor abnormalities.

RESULTS

After adjusting for covariates, the OR (95% CIs) of physical abnormalities for a one-unit rise in Mn concentrations in all individuals were 1.26 (1.08, 1.48). The OR (95% CIs) of physical abnormalities in the 4th quartile (≥18.7 ng/g) were 1.06 (1.01, 1.13) (p-value for the trend = 0.034) compared with those in the 1st quartile (≤12.5 ng/g).

CONCLUSION

In Japan, maternal blood Mn concentrations above threshold during pregnancy may slightly increase the incidence of physical abnormalities.

IMPACT

Physical abnormalities (including minor anomalies and congenital anomalies) are associated with prenatal manganese concentrations. They are not associated with cadmium, lead, mercury, and selenium concentrations.

Placental levels of essential and non-essential trace element in relation to neonatal weight in Northwestern Spain: application of generalized additive models

Adequate gestational progression depends to a great extent on placental development, which can modify maternal and neonatal outcomes. Any environmental toxicant, including metals, with the capacity to affect the placenta can alter the development of the pregnancy and its outcome. The objective of this study was to correlate the placenta levels of 14 essential and non-essential elements with neonatal weight. We examined relationships between placental concentrations of arsenic, cadmium, cobalt, copper, mercury, lithium, manganese, molybdenum, nickel, lead, rubidium, selenium, strontium, and zinc from 79 low obstetric risk pregnant women in Ourense (Northwestern Spain, 42°20'12.1″N 7°51.844'O) with neonatal weight. We tested associations between placental metal concentrations and neonatal weight by conducting multivariable linear regressions using generalized linear models (GLM) and generalized additive models (GAM). While placental Co (p = 0.03) and Sr (p = 0.048) concentrations were associated with higher neonatal weight, concentrations of Li (p = 0.027), Mo (p = 0.049), and Se (p = 0.02) in the placenta were associated with lower newborn weight. Our findings suggest that the concentration of some metals in the placenta may affect fetal growth.

Prenatal exposure to silver is associated with an elevated risk for neural tube defects: a case-control study

Exposure to copper, silver, and titanium has been reported to be associated with a variety of adverse effects on humans, but it is little focused on the fetus. We investigated the associations between prenatal exposure to the three metals (copper, silver, and titanium) and risk for fetal neural tube defects (NTDs). Placental samples from 408 women with pregnancies affected by NTDs and 593 women with normal pregnancies were collected from 2003 to 2016 in Pingding, Xiyang, Shouyang, Taigu, and Zezhou counties of China. Multilevel mixed-effects logistic regression and Bayesian kernel machine regression (BKMR) were used to evaluate the single and joint effects of the metals on NTDs. Silver was associated with an increased risk for NTDs in a dose-response fashion in single-metal logistic regression, with adjusted odds ratios (95% confidence intervals) of 1.78 (1.04-3.06) and 1.92 (1.11-3.32) in the second and third tertiles, respectively, compared to the lowest tertile. BKMR revealed toxic effects of silver on NTDs and the association appeared to be linear. No interaction of silver with any of the other two metals was observed. Besides, silver concentration was positively correlated with maternal certain dietary intakes. Placental high silver concentrations are associated with an elevated risk for NTDs. Maternal diet may be a source of silver exposure.

Maternal Zinc, Copper, and Selenium Intakes during Pregnancy and Congenital Heart Defects

The effects of zinc, copper, and selenium on human congenital heart defects (CHDs) remain unclear. This study aimed to investigate the associations of the maternal total, dietary, and supplemental intakes of zinc, copper, and selenium during pregnancy with CHDs. A hospital-based case-control study was performed, including 474 cases and 948 controls in Northwest China. Eligible participants waiting for delivery were interviewed to report their diets and characteristics in pregnancy. Mixed logistic regression was adopted to examine associations and interactions between maternal intakes and CHDs. Higher total intakes of zinc, selenium, zinc to copper ratio, and selenium to copper ratio during pregnancy were associated with lower risks of total CHDs and the subtypes, and the tests for trend were significant (all p < 0.05). The significantly inverse associations with CHDs were also observed for dietary intakes of zinc, selenium, zinc to copper ratio, selenium to copper ratio, and zinc and selenium supplements use during pregnancy and in the first trimester. Moreover, high zinc and high selenium, even with low or high copper, showed a significantly reduced risk of total CHDs. Efforts to promote zinc and selenium intakes during pregnancy need to be strengthened to reduce the incidence of CHDs in the Chinese population.

Prenatal exposure to barium and the occurrence of neural tube defects in offspring

Neural tube defects (NTDs) have a complex etiology. Few studies have assessed alkaline earth metals exposures and occurrence of NTDs. We examined the association between prenatal exposure to magnesium (Mg), calcium (Ca), strontium (Sr) and barium (Ba) and risk for NTDs in a case-control study, and assessed the teratogenic effects of Ba on mice. Placentas were collected from 408 women with NTD-affected pregnancies and 593 women who delivered healthy infants, and concentrations of these metals were determined as prenatal exposure markers. The single effect of individual exposure and joint effect of coexposure to these metals were evaluated with logistic regression and Bayesian kernel machine regression (BKMR), respectively. Barium chloride (BaCl₂) was intragastrically administered to pregnant ICR mice and fetal mice were examined for NTDs. Median concentrations of Mg and Ba were higher in NTD cases than in controls (P_all < 0.001). In logistic regression, higher levels of Ba were associated with 1.6-fold increased risk for NTDs (95% confidence interval: 1.06-2.43). In BKMR, the joint effect of the four-metal mixture on NTD risk increased steadily with the levels of the mixture. A change in Ba concentration from the 25^th to 75^th percentile displayed a risk effect when the other three metals were fixed at the 25^th, 50^th or 75^th percentile, while such a change in Ca concentration showed a protective effect when the other metals were held at the 25^th or 50^th percentile. No interactions among metals were found. In the mouse experiment, dams treated with 200 mg/kg BaCl₂ showed 16.8% of NTDs in fetal mice, compared to 2.6% in the untreated control group (P < 0.01). Taken together, higher mixture levels of the four alkaline earth metals were associated with increased risk for NTDs, with Ba being the major contributor for the joint effect. Intragastric administration of Ba can induce NTDs in mice.

Concentrations of organochlorine pesticides in placental tissue are not associated with risk for fetal orofacial clefts

Previous epidemiological studies have shown that prenatal exposure to organochlorine pesticides (OCPs) entails a variety of adverse impacts on fetal health, but it is not yet known whether it is associated with risk for orofacial clefts (OFCs). This study of 103 fetuses or newborns with a diagnosis of OFCs (cases) and 103 healthy newborns without malformations (controls) examined whether prenatal exposure to OCPs, as indicated by their concentrations in placental tissue, is a risk factor for OFCs. No differences were found in the median concentrations of OCPs between cases and controls, with exception of o,p'-dichlorodiphenyldichloroethylene, o,p'-dichlorodiphenyldichloroethane, and total o,p'-dichlorodiphenyltrichloroethane (DDTs), whose concentrations were higher in controls than in cases (Ps < 0.05). Although higher concentrations of placental δhexachlorocyclohexane and isodrin were found to be associated with decreased risk for OFCs in logistic regression, no association was observed in the Bayesian kernel machine regression, a novel statistical model in analyzing exposure mixtures. Women who reported periconceptional folic acid supplementation had lower placental concentrations of DDTs than women who did not. In conclusion, no association between levels of OCPs in placental tissue and risk for OFCs was observed in this population. Supplementation with folic acid may help decrease the levels of DDTs in placental tissue, but further studies are needed to confirm this unexpected finding.

Selected essential trace elements in maternal serum and risk for fetal orofacial clefts

BACKGROUND

Disturbances in the homeostasis of essential trace elements (ETEs) may interfere with embryonic organogenesis. However, the effect of ETEs on the development of orofacial clefts (OFCs) remains unclear.

OBJECTIVES

This study examined associations between concentrations of iron (Fe), zinc (Zn), selenium (Se), cuprum (Cu), cobalt (Co), and molybdenum (Mo) in maternal serum and risk for OFCs in offspring.

METHODS

A total of 130 cases of OFCs and 260 nonmalformed controls were included in this study. Concentrations of Fe, Zn, Se, Cu, Co, and Mo in maternal serum were detected by inductively coupled plasma mass spectrometry. We examined associations between levels of the six ETEs in maternal serum and risk for OFCs for each element separately using multilevel mixed-effects logistic regression and for all elements collectively using Bayesian kernel machine regression (BKMR).

RESULTS

Higher concentrations of Mo and Co in maternal serum were associated with a decreased risk for OFCs in a dose-dependent manner, with odds ratios and 95% confidence intervals of 0.37 (0.20-0.66) for the second tertile of Mo, 0.28 (0.15-0.54) for the third tertile of Mo, 0.54 (0.29-1.00) for the second tertile of Co, and 0.47 (0.25-0.87) for the third tertile of Co, with the lowest tertile as the referent. When all six ETEs were considered together, increased levels of ETEs were associated with a decreased risk for OFCs. In addition, Mo showed a protective effect against risk for OFCs when the other ETEs were fixed at their 25th, 50th, or 75th percentile, whereas the protective effect of Co turned to a null effect in the BKMR model. No association was observed between levels of Fe, Zn, Se, or Cu and risk for OFCs in either statistical model.

CONCLUSION

Elevated concentrations of Mo in maternal serum were associated with a reduced risk for OFCs.

High maternal selenium levels are associated with increased risk of congenital heart defects in the offspring

OBJECTIVE

To examine whether maternal hair or cord blood selenium levels are associated with infant congenital heart defects (CHDs).

METHOD

A hospital-based case-control study was performed with samples collected from 2010 to 2014. Selenium levels in maternal hair and fetal cord serum were measured using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Data from medical records of infants with CHDs were collected. Logistic regression analysis was employed to examine the independent association between maternal selenium exposure and fetal CHD.

RESULTS

In total, 888 pregnant women were included in this study. Median (interquartile range) selenium levels in of maternal hair was similar in the control and CHD group. A significant association was detected between increased maternal hair selenium concentration and CHDs in offspring (adjusted odds ratio [aOR] 3.57, 95 %CI, 1.90-6.70). The association was present in all CHD groups, including septal defects, conotruncal defects, left ventricular outflow tract obstruction, right ventricular outflow tract obstruction, and anomalous pulmonary venous return.

CONCLUSION

High maternal selenium level is significantly associated with the occurrence of fetal CHD.