ABSTRACT
Cadmium is a toxic metal, an environmental contaminant and a multi-organ poison which has been implicated in the derangement of a number of biological and molecular systems. Exposure to cadmium is a serious global health threat particularly in developing countries and pregnant women are at great risk, This is because they have increased gastrointestinal absorption and retention of cadmium and the tendency for increased risk of complications owing to its toxic effects. Preeclampsia is a pregnancy complication characterized by the development of onset of hypertension and significant proteinuria after 20 weeks of gestation or during labour and/or within 48 hours of delivery. This pregnancy-specific syndrome is a leading cause of maternal death particularly in developing countries. Several reports have provided evidence of remote association between preeclampsia and cadmium but the mechanism of the involment of this toxic metal in this disease is still surrounded with uncertainty. Some possible mechanistic pathways such as induction of oxidative stress, acting as an antimetabolite to zinc and deregulation of epigenetic mechanisms have been elucidated in this article may be interconnected, work synergistically or act independently. However, pertinent to understand them in a bid to possibly prevent the disease or forestall its devastating consequences. Environmental cadmium exposure may be considered a factor that merits further serious attention in the continuous search for the precise an etiology of preeclampsia particularly in developing countries that experience uncontrolled cadmium release into the environment.
ABSTRACT
Background: In the continuous search for accessible, reliable and sensitive biomarkers for early detection of environmental lead exposure, authors determined the interaction between blood lead level (BLL), the conventional marker of lead exposure, and the indices of calcium and bone metabolism in children.Methods: This cross-sectional study involved 309 apparently healthy children from eight public primary schools in Ibadan, Nigeria who were classified as Elevated BLL (EBLL) and control based on standard cut-off for childhood BLL. BLL, serum Ca (tCa), phosphate, magnesium (Mg), 25-hydroxy-Vitamin D, alkaline phosphatase (ALP), urinary calcium (uCa) and urinary deoxypyridinoline (uDPD) were determined using AAS, HPLC and ELISA as appropriate. Bone-specific ALP (B-ALP) and ionized calcium (iCa) were calculated using standard formulae. Data analyses involved Student’s t-test, Pearson correlation and multivariate regression analysis. p<0.05 was considered statistically significant.Results: BLL and 25-OH-Vitamin D levels were increased in EBLL (0.4±0.1 µmol/L and 60.1±10.7 mmol/L) compared with control (0.2±0.0 µmol/L and 55.1±14.3 mmol/L) p <0.05. No significant differences existed in the levels of ALP, B-ALP, uCa, uDPD, tCa, iCa, phosphate and Mg in both groups (p>0.05). BLL had significant positive correlation with uCa (r=0.176, p=0.002) (p<0.05) but no significant correlation with uDPD, ALP, B-ALP, tCa, iCa, phosphate, Mg and 25-OH-Vitamin D (p>0.05). BLL could be accounted for by uCa by applying the equation, BLL=0.329+0.324uCa.Conclusions: Urinary calcium could be a promising predictive biomarker for early recognition of significant environmental lead exposure in children.