Trend of childhood blood lead levels in cities of China in recent 10 years

The Performance Comparison of Socioeconomic and Behavioural Factors as Predictors of Higher Blood Lead Levels of 0–6-Year-Old Chinese Children between 2004 and 2014

Childhood lead exposure is a commonly known risk factor affecting children’s health, and 10 governments have taken actions to reduce children’s lead exposure sources. Because lab testing for children’s blood lead levels (BLLs) was not popularized easily, socioeconomic and behavioural factors have been usually used as predictors of screening methods. Along with the overall decreasing trend of children’s BLLs, the lead-exposure-potential-predicting ability of such factors might be limited or changed over time. Our study aims to compare the predicting ability of multiple factors, including the living environment, economic disparity and personal behaviour differences between 2004 and 2014. With potential predicting factors identified, it could provide direction in identifying individual children facing high-risk lead exposure in the unit of clinics or communities of China. The study was first conducted in 12 cities in China in 2004 and then repeated in 2014 in the same 12 cities with the same method. In total, 27,972 children aged under 7 years were included in this study. With confounding factors adjusted, the child’s age, the family’s socioeconomic status and the child’s personal hygiene habit, especially biting toys, continued to be important predictors of higher blood lead levels among Chinese children. The sex of the child was no longer a predictor. Factors such as the father’s occupational contact with lead, residence near the main road and taking traditional Chinese medicine had the potential to be new predictors.

Evaluation of Essential and Toxic Elements in the Blood of 0–14-Year-Old Children in Hunan, China From 2013 to 2019: A Retrospective Analysis

Objective

The aim was to investigate the distribution and correlation of Ca, Mg, Zn, Cu, Fe, Pb, and Cd in the blood of children aged 0–14 years in Hunan, China, which may serve to provide a basis for clinical guidance on child health.

Study Design

A retrospective analysis was carried out. Concentrations of all elements were determined by atomic absorption spectrophotometry. Distributions were analyzed and compared among different age, sex, and year groups by the Kruskal–Wallis test, the chi-square test, and the Fisher's exact test. Spearman's rank correlation coefficient was used to evaluate the association between every pair of elements.

Results

A total of 46,951 children were involved in this study from 2013 to 2019. The median blood levels of elements were 13.51 μmol/L (Cu), 58.69 μmol/L (Zn), 1.70 mmol/L (Ca), 1.40 mmol/L (Mg), 7.46 mmol/L (Fe), 35.00 μg/L (Pb), and 1.00 μg/L (Cd). Girls had a higher level of Ca and lower levels of Pb and Cd than boys. Cu and Ca showed an upward trend, and Mg and Pb showed a downward trend by year. Zn and Fe increased and Ca decreased significantly with age. The deficiency rates of Fe and Zn decreased significantly by year, while Ca and Cu increased significantly by year. Cd exposure in this area was relatively low.

Conclusion

Most children had normal levels of the essential elements Ca, Cu, and Mg and the toxic elements Pb and Cd. Severe deficiencies in Zn and Fe were observed in the relatively younger children but improved with age. Persistent efforts in reducing Pb exposure might still be needed.

Uneven development of the lead industry leads to regional differences in blood lead levels of children

Children's exposure to lead is a global health problem, especially in low- and middle-income countries. However, research on the relationship between children's blood lead levels (BLLs) and the development of the lead industry is still limited. This study examined whether children's BLLs were associated with the development of lead industry in different regions. Using survey data on the BLLs of children living in 250 prefectures in China with corresponding data on their economic factors and lead industries, we explored the regional variation of children's BLLs using statistical methods. The results show that the level of economic development in leaded areas was associated with inequity in children's BLLs and met the environmental Kuznets hypothesis. In areas without lead industries, there was little correlation between the level of economic development and the BLLs of children and thus the environmental Kuznets hypothesis was not supported. Lead mines, lead smelting and chemical companies are major sources of blood lead in children living in leaded areas. This study demonstrated the success of control policies for lead-acid battery manufacturers in promoting the prevention and control of childhood lead poisoning in China. China should consciously support the improvement of children's BLLs in undeveloped areas with lead industries through national financing and policies to avoid the continuous effects of the regional inequality problem of high children's BLLs.

Regional characteristics of children's blood lead levels in China: A systematic synthesis of national and subnational population data

The blood lead levels (BLLs) of children in China remain notably high in many areas. We aimed to summarise the relevant regional characteristics, identifying problematic areas and the causes of lead pollution. We searched the databases of PubMed, China National Knowledge Infrastructure (CNKI), and Wanfang Data, systematically reviewing 219 articles published from January 2010 to September 2020. In doing so, we assessed the BLLs noted in 220 prefectures across China. Data were organised using Geographic Information Systems (GIS) mapping. Out of a total of 629,627 children sampled, we found that the average blood lead level (BLL) of children included in our study is 50.61 ± 13.63 μg/L, which slightly exceeds the 50.00 μg/L US standard. Within the sample, 8.75% had BLLs higher than 100.00 μg/L. Children living in Liaoning, Hebei, Shanxi, Jiangxi, Anhui, Fujian, Guizhou, Yunnan, and Guangxi had notably high BLLs, at more than 60.00 μg/L. A total of 112 municipalities had an average children's BLL above 50.00 μg/L. Furthermore, Chenzhou, Linfen, Yuncheng, and Hechi had the highest children's BLLs, with average values above 100.00 μg/L. The leading contributors to lead pollution are lead mining, lead recovery and the smelting industry. Nonetheless, the lead-acid battery industry needs more attention. Although data suggest that BLLs are decreasing in China, many areas still have high BLLs that need to be monitored. Moreover, national standards must improve to decrease acceptable BLL thresholds for children.

Association of serum microcystin levels with neurobehavior of school-age children in rural area of Southwest China: A cross-sectional study

To investigate whether microcystin-LR (MC-LR) influences children's cognitive function and memory ability, we measured serum MC-LR and whole blood lead levels in 697 primary students, and collected their academic and neurobehavioral test scores. The median of serum MC-LR levels was 0.80 µg/L (the value below the limit of detection to 1.67 µg/L). The shapes of the associations of serum MC-LR levels (cut-point: 0.95 µg/L) with scores on academic achievements, digit symbol substitution test and long-term memory test were parabolic curves. Logistic regression analysis showed that MC-LR at concentrations of 0.80-0.95 µg/L was associated with the increased probability of higher achievements on academic achievements [odds ratio (OR) = 2.20, 95% confidence interval (CI): 1.28-3.79], and also with scores on digit symbol substitution test (OR = 1.73, 95% CI: 1.05-2.86), overall memory quotient (OR = 2.27, 95% CI: 1.21-4.26), long-term memory (OR = 1.85, 95% CI: 1.01-3.38) and short-term memory (OR = 2.13, 95% CI: 1.14-3.98) after adjustment for confounding factors. Antagonism of MC-LR and lead on long-term memory was observed (synergism index = 0.15, 95% CI: 0.03-0.74). In conclusion, serum MC-LR at concentrations of 0.80-0.95 µg/L was positively associated with higher scores on cognitive and neurobehavioral tests, and antagonism between MC-LR at concentrations of 0.80-1.67 µg/L and lead exposure was obviously observed on long-term memory in children. Concerning that MC-LR is a neurotoxin at high doses, our observation is interesting and need further investigation.

Pb Toxicity on Gut Physiology and Microbiota

Lead (Pb) is a toxic heavy metal, having profound threats to the global population. Multiple organs such as kidney, and liver, as well as nervous, hematologic, and reproductive systems, are commonly considered the targets of Pb toxicity. Increasing researches reported that the effects of Pb on gastrointestinal tracts are equally intensive, especially on intestinal microbiota. This review summarized Pb toxicity on gut physiology and microbiota in different animal models and in humans, of which the alterations may further have effects on other organs in host. To be more specific, Pb can impair gut barrier and increase gut permeability, which make inflammatory cytokines, immunologic factors, as well as microbial metabolites such as bile acids (BA) and short-chain fatty acids (SCFAs) enter the enterohepatic circulation easily, and finally induce multiple systematic lesion. In addition, we emphasized that probiotic treatment may be one of the feasible and effective strategies for preventing Pb toxicity.

Time for a change in blood lead reference value for Chinese children

In China, the first and also the latest version of national childhood lead exposure control guidelines was issued by the National Health Commission in 2006, when the reference value of high blood lead exposure was set at 100 μg/L and lead poisoning was set at 200 μg/L. Lead exposure levels have been decreasing in China over the last few decades, with almost all blood lead concentrations in children under 7 years of age being under 100 μg/L in non-industrial areas. However, lead concentrations lower than 100 μg/L in blood in children are associated with neurodevelopmental deficits. Thus, if the reference value remains at a high level, a large percent of children with exposure levels that are high but lower than the current reference value will be diagnosed as 'safe' and be ignored. Thus, we appeal that the reference value should be lowered according to local actual exposure level. A more stringent reference value would give care givers, doctors, communities, and officials more opportunities to take action earlier.

Adverse health effects of lead exposure on physical growth, erythrocyte parameters and school performances for school-aged children in eastern China

We conducted a cross-sectional study with 395 completely matched student samples enrolled from a public primary school in Nanjing of eastern China, including questionnaires, blood samples, growth indexes and school performances, all of which were used for the analysis of variance (ANOVA) and general linear model (GLM). The results showed that factors, such as gender, age, parents' education, residential passive smoking and picky eaters, had significant impacts on the blood lead levels (BPbs). As for the linear and non-linear dose-response relationship between BPbs and erythrocyte parameters, we found a positive association between BPbs and red blood cell count (RBC count) and mean corpuscular hemoglobin concentration (MCHC) but a negative association between BPbs and hemoglobin (HGB), hematocrit (HCT), mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH). When BPbs increased by 10 μg/L, the RBC count increased by 0.18 × 10¹²/L, while HGB and HCT decreased by 1.19 g/L and 0.41% for boys, respectively. As for girls, corresponding increases in RBC count was 0.05 × 10¹²/L, while HGB and HCT decreased by 0.82 g/L and 0.23%. Meanwhile, for both boys and girls, MCHC increased by 2.55 g/L, while MCV and MCH levels decreased by 0.41 fL and 0.12 pg each. Furthermore, a remarkable adverse effect (p < 0.05) was observed on children's school performances as a result of increased BPbs. As BPbs increased by 10 μg/L, children's scores for Chinese, Math and English decreased by 0.42 points, 0.39 points and 0.87 points, respectively. In summary, our study indicated that lead exposure can have adverse health effects on children's erythrocyte parameters, BMI, and school performances.

Modulation of the gut microbiota by a galactooligosaccharide protects against heavy metal lead accumulation in mice

The heavy metal lead (Pb) is a toxic contaminant that induces a range of adverse effects in humans. The present study demonstrated for the first time that dietary supplementation with a galactooligosaccharide (GOS) promotes fecal Pb excretion and reduces Pb accumulation in the blood and tissues of mice. The effects against Pb exposure were also observed in mice that received the fecal microbiota from donors treated with GOS, but were diminished in gut microbiota-depleted mice that received antibiotic pre-treatment, indicating that the protection by GOS administration was dependent on the modulation of the gut microbiota. We also provide evidence that the protective mechanism of GOS supplementation was related to the enhanced abundance of intestinal bacteria with good Pb-binding ability, recovery of the gut barrier function, modulation of bile acid metabolism, and improved essential metal utilization. These results indicate that GOS can be considered a potentially protective prebiotic against Pb toxicity.

Potential dietary factors for reducing lead burden of Chinese preschool children

Dietary approaches to treat children's low lead exposure are implemented routinely in China, while evidence for the effect could not be provided until now. The aim of this study was to examine the relationship between diets including nutrition supplementation and blood lead level of preschool children of China. In total, 17,859 preschool children from 14 cities were recruited, and their social-demography, living environment, and dietary intakes were collected, and capillary blood sample was tested for lead concentration. The average blood lead concentration was 34.5 μg/L, and after adjusting children's social-demography factors, the consumption of milk or dairy production, fruits, and calcium supplementation had negative dose-response relationships with blood lead level. Conversely, intake of iron-rich food and supplementation was not associated. Further studies are needed to prove the causal relationships.

Elevated lead levels from e-waste exposure are linked to sensory integration difficulties in preschool children

Exposure to lead is associated with adverse effects on neurodevelopment. However, studies of the effects of lead on sensory integration are few. The purpose of this research is to investigate the effect of lead exposure on child sensory integration by correlating the blood lead levels of children with sensory processing measures. A total of 574 children, from 3 to 6 years of age, 358 from an electronic waste (e-waste) recycling town named Guiyu, and 216 from Haojiang, a nearby town with no e-waste recycling activity, were recruited in this study. The median blood lead level in Guiyu children was 4.88 μg/dL, higher than the 3.47 μg/dL blood lead level in Haojiang children (P <  0.001). 47.2% of Guiyu children had blood lead levels exceeding 5 μg/dL. The median concentration of serum cortisol, an HPA-axis biomarker, in Guiyu children was significantly lower than in Haojiang, and was negatively correlated with blood lead levels. All subscale scores and the total score of the Sensory Processing Measure (Hong Kong Chinese version, SPM-HKC) in Guiyu children were higher than Haojiang children, indicating greater difficulties, especially for touch, body awareness, balance and motion, and total sensory systems. Sensory processing scores were positively correlated with blood lead, except for touch, which was negatively correlated with serum cortisol levels. Simultaneously, all subscale scores and the total SPM-HKC scores for children with high blood lead levels (blood lead > 5 μg/dL) were higher than those in the low blood lead level group (blood lead < 5 μg/dL), especially for hearing, touch, body awareness, balance and motion, and total sensory systems. Our findings suggest that lead exposure in e-waste recycling areas may result in a decrease in serum cortisol levels and an increase in child sensory integration difficulties. Cortisol may be involved in touch-related sensory integration difficulties.

Lactobacillus plantarum CCFM8661 modulates bile acid enterohepatic circulation and increases lead excretion in mice

Probiotics modulate bile acid enterohepatic circulation and increases lead excretion.

The breast milk lead levels among Chinese population

Breast milk is a potential source of infant and young children lead exposure, but national-level data on breast milk lead (BML) is unknown in China. To fill up this gap, we conducted a review by analyzing the articles enrolled through searching Wanfang MedOnline, CNKI, SinoMed, Pubmed, and Embase databases and relevant articles from 2000 through 2017. After screening and assessing process, 17 articles were included. The average concentrations of BML in these studies varied with regions (1.54-171.84 μg/L), and the BML level was dropping down in general. In conclusion, breast milk should still be encouraged to infant and young children in normal areas of China, and stopping breastfeeding should be considered prudently. Education for health workers and families on BML should be strengthened, and more surveys on BML should be conducted.