Blood lead status and influencing factors among preschool children in urban areas of China

Abstract

To investigate the blood lead status and influencing factors among preschool children in the sampling city. Stratified-clustered-random sampling was used. Standardized questionnaire and peripheral blood samples were obtained from 69 968 children aged 0-6 years in fixed kindergartens and communities of Yinchuan, Xi'an, Chengdu, Wuhan, Hefei, Beijing, Harbin, Zhengzhou, Huhhot, Shijiazhuang, Haikou, Dalian, Qingdao, Guangzhou, Nanning and Changsha from 2004 to 2008, respectively. Tungsten atomic absorbtion spectrophotometry was employed to determine the blood lead level of children. The proportion of children with blood lead level ≥ 100 µg/L was 7.57% (among which the proportion of high blood lead level, mild lead poisoning, moderate lead poisoning, severe lead poisoning were 91.0%, 2.76%, 3.32%, 2.93%, respectively) and the blood lead level was lower than those of the past studies. The proportion of high blood lead level has steadily declined from 2004 to 2008 [the proportions were 10.03%, 7.85%, 7.40%, 6.91% and 4.78%, respectively (χ(2) = 297.36, P < 0.0001)]. The proportion of children with blood lead level ≥ 100 µg/L in Haikou, Zhengzhou, Guangzhou, Shijiazhuang, Changsha, Xi'an, Wuhan, Hefei, Chengdu, Yinchuan, Harbin, Beijing, Dalian, Huhhot, Nanning and Qingdao were 12.15%, 10.49%, 10.37%, 9.69%, 9.53%, 9.46%, 9.40%, 8.50%, 7.99%, 7.98%, 7.51%, 6.10%, 3.25%, 2.89%, 2.46% and 2.39%, respectively (χ(2) = 768.21, P < 0.0001). By multiple regression method, the risk factors which influenced blood lead status of children were education status of mother, older children, behavior and dietary habit of children, boy, stay for long time in traffic busy areas, the type of housing, taking traditional Chinese and herbal medicine. The protective factors against lead poisoning in children mainly included scattered living, the nutritional status of calcium, iron, zinc, frequent intake of milk, and older mother. The blood lead level of children has decreased, but is still higher than those in developed countries. Lead exposure remains a public health issue which affects children most. The blood lead level of children is affected by multiple factors. Government and the whole society should pay attention to interrupt the lead pollutant and to promote nutritional health education. With all these efforts, it is possible to stop the progress of lead exposure and reduce its hazardous effects on the growth and development of children.