Effects Of Environmental Hearvy Metals Exposure On Children’s Neurodevelopment And Early Kidney Damage In An Industrial Area In Southern China

Study on relationship between environmental pollutions and nervous system adverse effects in children is a very important research field in environmental health recently.In China,companying with the rapid economic development which were the costs of energy excessive consumption and environmental pollution,a large number of pollutants were released into the environment by waste gas,waste water,solid waste over the years.These pollutions are posing a great potential threat to human health.Environmental heavy metal(loid)s pollution are elusive,perennial,cumulative and inevasible.Because of theses characteristics,heavy metal(loid)s can be consumed by human through drinking water,food,and air,which maybe result in acute and chronic health damage,even serious chronic poisoning,such as the well-known public nuisance disease,minamata disease caused by environmental mercury pollution and itai-itai disease caused by environmental cadmium pollution.Because of immature metabolism system in children,children are more susceptible to environmental pollutions.And many studies have shown that heavy metal(loid)s can lead to children’s nervous system irreversible harmful effects and childhood heavy metal(loid)s exposure can effect disease in adult.But there are some problems in the study on the relation between environmental heavy metal(loid)s pollution and children’s health.Firstly,there is less data about low heavy metal(loid)s exposure level in children in typical exposed area.Secondly,epidemiology survery of the synergistic impact of two or more metal(loid)s at relatively low levels on children’s intellectual function is few.Finally,whether the reference standard in China of 100 μg/L blood lead for children should be revised.So,in the present cross-sectional study,9-11 aged children from an exposed industrial district(the determined environmental metals pollution area by the Ministry of Environmental Protection)and in a non-exposed reference area in the same city were randomly selected as object of study.The intelligence and psychomotor of children were tested and questionaire was used to collecte possible confounders.The levels of lead,cadmium,arsenic,mercury in environmental samples(food,drinking water and soil)and biological samples(blood,urine of children)were detected.And early health damage indicators in urine were also detected.The main research results and conclusions were summed up as following.1.Of the environmental samples in this study,Cadmium in rice(1.41 mg/kg),kale(0.24 mg/kg),swamp cabbage(0.15 mg/kg),arsenic in rice(0.19 mg/kg),swamp cabbage(0.16 mg/kg),and lead concentration in rice(0.18 mg/kg),swamp cabbage(0.26 mg/kg)in the exposed area were higher than cadmium in rice(0.20 mg/kg),kale(0.14 mg/kg),swamp cabbage(0.07 mg/kg),arsenic in rice(0.13 mg/kg),swamp cabbage(0.10 mg/kg),and lead concentration in rice(0.13 mg/kg),swamp cabbage(0.13 mg/kg)in the no-exposed area,respectively.At the same time,cadmium level in rice and lead,cadmium levels in kale and swamp cabbage in both areas were above the Chinese government food standards(0.20 mg/kg).Especially in the exposed area,cadmium levels in rice surpassed(7-fold higher)the Chinese government food standards.Levels of lead,cadmium,mercury in soil in the exposed area were significantly higher(2-fold higher)than in the exposed area(p<0.05),respectively.These results suggested that heavy metal(loid)s in environment were transfered into food,which posed a threat to human health.In addition,environmental heavy metal(loid)s pollution in the exposed area was expanded into the nearby.2.Results about metal(loid)s levels in blood and urine of children showed that compared with children in the no-exposed area,children in the exposed area had significant higher lead and cadmium levels both in blood and urine(p<0.001).At the same time,there was sex differences in exposure to these metal(loid)s.In the noexposed area,lead and mercy concentrations in blood of boys(39.36 μg/L and 1.73 μg/L,respectively)were significant higher than lead and mercy concentrations in blood of girls(39.36 μg/L and 1.73 μg/L,respectively,p<0.05).In the exposed area,lead and mercy concentrations in blood(72.61 and 1.66 μg/L,respectively)and cadmium,arsenic,mercy in urine of boys(1.62,31.92 and 0.40 μg/L,respectively)were significant higher than lead and mercy concentrations in blood(60.67 and 1.45 μg/L,respectively)and cadmium,arsenic,mercy in urine of boys(1.29,27.23 and 0.34 μg/L,respectively).In addition,children in the exposed area had significant higher β2-microglobulin and retinol-binding protein(RBP)than children in the no-exposed area(p<0.001).The results suggested that environmental heavy metal(loid)s pollution had resulted in higher heavy metal(loid)s levels in children,and this posed a certain potential threat to children’s health.3.Compared with children in the no-exposed area,children in the exposed area had significant lower intelligence quotient(IQ)scores(103.38±10.755 vs 106.23±12.838,p<0.05).Meanwhile,the distribution of IQ scores medium or below medium(below 109 scores)was higher in children in the exposed area.Compared with children in the no-exposed area,children in the exposed area had significant lower psychomotor scores in Numbers scratching,Numeral connection,Target tracking(p<0.001).These results suggested that environmental heavy metal(loid)s pollution in the study had an adverse impact on children’s intellectual and decreased the overall IQ of the exposed children,which caused few children with high intelligence.In addition,environmental heavy metal(loid)s pollution maybe affect children’s psychomotor function.4.Multiple linear regression analysis after adjusting confounders showed that only blood lead was significantly negatively associated with children’s IQ when children were co-exposured to environmental lead,cadmium,arsenic and mercy.When comparing the lowest(35.65 μg/L)and highest(70.65 μg/L)blood lead quartiles,children’s IQ scores decreased by 3.5 points.Analysis of the interactions suggested that there were possible interactions between these metal(loid)s,which require further investigation to be confirmed.Further analysis of blood lead below 100 μg/L indicated that still only blood lead was significantly negatively associated with children’s IQ(p<0.05)and the children’s IQ scores decreased by approximately 3.23 points from the lowest blood lead quartile to the highest(from 34.68 μg/L to 67.53 μg/L),and only children in the highest quartile had a significant decline in IQ scores(p<0.001).These results indicated that only blood lead was associated with 9-11 aged children’s IQ at this relatively low level of environmental heavy metal(loid)s pollution in an industrial area and added weight to the evidence that blood lead below 100 μg/L can also cause adverse effects on children’s IQ,which suggested that the reference 100 μg/L blood lead for children in China should be considerd to be revised.Large sample and cohort study are need to explore relationship between long time,low level simultaneous exposure to heavy metal(loid)s and children’s neurodevelopment.