Soil Ingestion Among Children 0-3 Years Old in Rural Bangladesh

摘要

Ingestion of soil and dust is a primary pathway of children's exposure to several environmental contaminants, including lead and pesticides. Previous estimates of soil consumption by children in high-income countries range from 3.8-448 mg/day, with the most recent studies estimating 32-62 mg/day. The estimates for children in low-income countries range from 2-21 g/day. However, the sophisticated modeling that has been applied in high-income countries has not previously been applied in low-income countries. We modeled the mass of soil ingested per day by rural Bengali children using a Monte Carlo simulation. We combined anthropometric and observational data of children <3 years old in rural Bangladesh with measurements of soil mass on the hands of children and their mothers. Unlike previously published activity pattern simulations of soil ingestion, which estimated ingestion based on hand-to-mouth and object-to-mouth contacts, our model also includes ingestion of soil placed directly into the mouth. Among children <6 months old, mean ingestion of soil was 66 mg/day (standard deviation [sd] = 262). Values were similar among children 6-11 months old (mean = 82 mg/day [sd = 201]). Compared to young children, children >12 months old ingested significantly greater amounts of soil (p = 0.01), with a mean of 129 mg/day (sd = 212) among children 12-23 months old and a mean of 196 mg/day (sd = 335) among children 24-35 months old. The most influential parameters affecting the estimates were the frequency with which children put their own hands in their mouths and the efficiency of soil removal during hand-to-mouth contacts. Due to greater incorporation of empirical evidence, our estimates are 100-1000 times lower than previous estimates for rural children in low-income countries. Nonetheless, comparing our results to the most recent estimates for children in high-income countries, rural children in low-income countries may ingest more soil.