Evaluation of Toxic Metals and Essential Elements in Children with Learning Disabilities from a Rural Area of Southern Brazil

Abstract

Children’s exposure to metals can result in adverse effects such as cognitive function impairments. This study aimed to evaluate some toxic metals and levels of essential trace elements in blood, hair, and drinking water in children from a rural area of Southern Brazil. Cognitive ability and δ-aminolevulinate dehydratase (ALA-D) activity were evaluated. Oxidative stress was evaluated as a main mechanism of metal toxicity, through the quantification of malondialdehyde (MDA) levels. This study included 20 children from a rural area and 20 children from an urban area. Our findings demonstrated increase in blood lead (Pb) levels (BLLs). Also, increased levels of nickel (Ni) in blood and increase of aluminum (Al) levels in hair and drinking water in rural children were found. Deficiency in selenium (Se) levels was observed in rural children as well. Rural children with visual-motor immaturity presented Pb levels in hair significantly increased in relation to rural children without visual-motor immaturity (p < 0.05). Negative correlations between BLLs and ALA-D activity and positive correlations between BLLs and ALA-RE activity were observed. MDA was significantly higher in rural compared to urban children (p < 0.05). Our findings suggest that rural children were co-exposed to toxic metals, especially Al, Pb and Ni. Moreover, a slight deficiency of Se was observed. Low performance on cognitive ability tests and ALA-D inhibition can be related to metal exposure in rural children. Oxidative stress was suggested as a main toxicological mechanism involved in metal exposure.

Association between Blood Lead Levels and Delta-Aminolevulinic Acid Dehydratase in Pregnant Women

“…Blood lead levels in our study were lower than in some prior studies on blood lead and ALAD activity [12,13,15,22,23,29,30]. Nevertheless, we observed a significant association between blood lead and ALAD activity at blood lead levels of 2.2 µg/dL, well below the CDC recommended level of 5 µg/dL for children and pregnant women [31].…”

Toxic elements in packed red blood cells from smoker donors: a risk for paediatric transfusion?

“…Lead, on the other hand, is classified by the IARC as a possibly carcinogenic element (group 2B) for humans It acts mainly on heme synthesis and thiol‐containing enzymes, counteracting antioxidant mechanisms and increasing oxidative stress and apoptosis in different tissues . At the low end of the blood Pb concentration range, adverse effects include delayed sexual maturation, increased blood pressure, impaired renal glomerular filtration rate and delayed or impaired development of the central nervous system . In adults, once Pb is absorbed from different sources, almost 100% is excreted from the body within a couple of weeks .…”

“…Cadmium and lead are toxic to tissues such as kidneys, lungs, bones, heart, vessels, brain, and reproductive system, even at low concentrations . In children, lead is associated with impairments to physical growth, learning, and memory . Even at blood concentrations below 100 μg/l, it is associated to cognitive, behavioural, and psychological disorders, and can cause irreversible neurological impairment .…”

Effect of heavy metals on the readaptive processes in the urinary bladder

“…Taking into account, the technological development of the industry and the use of chemical fertilizers in agriculture led to environment pollution by HM 22 . However, the risk of concentration increasing of HM binds with living on the ecologically dangerous areas with disorders of metabolic processes, abnormal functioning and deepening of the consequences of their actions against the background of pollutants accumulation 19,23,24 . It is known that excessive concentrations of HMS are able to generate the reactive oxygen intermediates and free radicals and suppresses antioxidants that lead to oxidative stress.…”