Urinary Lead, Mercury And Cadmium Level And The Growth And Development Among Children In Rural Area

[Backgrounds]The adverse effects of environmental chemical pollutants on human’s health have been increasingly got widespread attention. Children’s physical development is not mature and they contact with the environment in different way compared with the adults. The same doses of chemicals may generate more severe effects on children. Heavy metals are the most famous chemicals because people are easily exposed to them in daily life. They are difficult to degrade and they can accumulate in children’s body, resulting in adverse effects on their body. Therefore it is imperative to concern the adverse effects of heavy metals on children’s health status. We chose Sheyang, a county in Jiangsu Province as our study site and selected the children who were born in the Hospital for Gynecology and Obstetrics in this county from June 2009 to January 2010 as our study subjects. The level of heavy metals lead, mercury and cadmium in urine in these children were measured and the relationship between the growth and development and the levels of heavy metals was studied.[Objectives]1. To observe the levels of heavy metals such as lead, mercury and cadmium in spot urine in children from aged 1 to age 3; to explore the factors that may affect the urinary levels of selected heavy metals.2. To observe the general growth and development and intellectual development of children; to explore the relationship with heavy metals (lead, mercury and cadmium) in urine.[Methods]1. Spot urine was collected and the ICP-MS was used to detect the levels of heavy metals lead, mercury and cadmium in urine with creatinine corrected.2. Questionairs were used to evaluate the factors that might influence the levels of heavy metals lead, mercury and cadmium in urine of three-year-old children.3. The height, weight, head circumference and chest circumference of children were measured by the standard methods.4. Gesell Developmental Scale was used to evaluate the intellectual development of children.5. The software of Epidata 3.1 was used to input the data. The software of SPSS19.0 was used to do t test, chi-square test, analysis of variance and multivariate linear regression. The model of proc mixed of SAS 9.2 was used for repeated measures analysis.Results1.619 children at age 1 (324 boys and 295 girls),404 children at age 2 (224 boys and 280girls) and 461 children at age 3 (236 boys and 225 girls) were surveyed. Among these 183 children (93 boys and 90 girls) continuously participated in the follow-up.2. Heavy metals such as lead, mercury and cadmium could be detected in urine and data showed that the loads of heavy metals in the children were in a stable range with a seasonal variation.The consumption of shrimp and shellfish might increase the urinary mecury level.3. The growth and development of these children in this county were in good condition compared with the national report. One-way analysis of the impact of levels of heavy metals in urine on three-year-old children’s growth showed:the height, weight, motor developmental quotient, adaptive behavior developmental quotient, language developmental quotient and individual-social behavior of three-year-old children were related with urinary lead levels; the motor developmental quotient of three-year-old children was related with urinary mercury levels; the height, weight,motor developmental quotient, adaptive behavior developmental quotient, language developmental quotient and individual-social behavior of three-year-old children were related with urinary cadmium levels. Furthermore, the comparison between two groups of children, with extremely high urinary level of heavy meatls or with lower urinary level of heavy meatls, showed the weight and adaptive behavior developmental quotient of three-year-old children were related with the levels of lead in urine; the motor developmental quotient and individual-social behavior of three-year-old children were related with the levels of cadmium in urine. The children with totally higher urinary lead, mercury and cadmium level had lower values of height, weight, head circumference, motor developmental quotient and individual-social behavior compared with others children, using tripartite grouping method. The multiple linear regression showed the height was related with the levels of cadmium in urine.4. The relationship between the health outcome and previous exposure showed the language developmental quotient of children at age 2 was associated with urinary mercury level at age 1; the language developmental quotient of children at age 3 was associated with urinary cadmium at age 1. The motor developmental quotient and language developmental quotient of children with totally continuous higher urinary mercury level were significantly low compared with other children, while the head circumference and chest circumference of children with totally continuous higher urinary cadmium level were significantly low.5. Analsis with one-way mixed linear model showed the height, weight, head circumference, chest circumference, motor developmental quotient, language developmental quotient and individual-social behavior were related with levels of lead in urine. The height, weight, head circumference, chest circumference, motor developmental quotient, language developmental quotient and individual-social behavior were related with the levels of mercury in urine. The height, weight and individual-social behavior were related with the levels of cadmium in urine. However, the multivariable mixed linear model analysis showed that the weight was related with the levels of mercury in urine.Conclusions1. The burden of heavy metals of children was in a stable range in this county.2. Children’s health eating habits might influence the levels of mercury.3. Children’s general growth and development was associated with the exposure of heavy metals lead, mercury and cadmium in non-polluted area.