Background

Ingestion of fluoride in drinking water has been shown to result in increased cellular markers of inflammation in rodent models. However, the approximately 5-10 × increase in water fluoride concentrations required in rat and mouse models to obtain plasma fluoride concentrations similar to those found in humans has made relevant comparisons of animal to human studies difficult to assess. As an increased white blood cell count (WBC) is a marker of inflammation in humans, we used available NHANES survey data to assess the associations between plasma fluoride levels in the U.S. and blood cell counts children and adolescents.   METHODS: Multiple linear regressions were done to determine the association of blood cell counts and plasma fluoride in publicly available NHANES survey data from the 2013-2014 and 2015-2016 cycles. Plasma fluoride concentration measurements were available only for children aged 6 to 19, inclusive, and therefore this subpopulation was used for all analyses. Covariate predictors along with plasma fluoride were age, ethnicity, gender, and Body Mass Index (BMI).  RESULTS: Plasma fluoride was significantly positively associated with water fluoride, total WBC count, segmented neutrophils, and monocytes, and negatively associated with red blood cell count when adjusted for age, gender and BMI.

Conclusion

Our finding that neutrophils and monocytes are associated with higher plasma fluoride in U.S. children and adolescents is consistent with animal data showing fluoride related effects of increased inflammation. These findings suggest the importance of further studies to assess potential mechanisms that are involved in absorption and filtration of ingested fluoride, particularly in tissues and organs such as the small intestine, liver and kidney.

Some evidence points to the positive effects of asset accumulation programs on mental health of children living in low-resource contexts. However, no evidence exists as to why and how such impact occurs. Our study aims to understand whether child poverty, child work, and household wealth serve as pathways through which the economic strengthening intervention affects the mental health of AIDS-orphaned children. The study employed a cluster-randomized experimental design with a family-based economic strengthening intervention conducted among 1410 school-going AIDS-orphaned children ages 10 and 16 years old in 48 primary schools in South Western Uganda. To test the hypothesized relationships between the intervention, mediators (household wealth, child poverty, and child's work) and mental health, we ran structural equation models that adjust for clustering of individuals within schools and account for potential correlation among the mediators. We found significant unmediated effect of the intervention on children's mental health at 24 months (B = -0.59; 95% CI: 0.93, -0.25; p < 0.001; β = -0.33). Furthermore, the results suggest that participation in the intervention reduced child poverty at 12 months, which in turn improved latent mental health outcome at 24 months (B = -0.14; 95% CI: -0.29, -0.01; p < 0.06; β = -0.08). In addition, though not statistically significant at the 0.05 level, at 36 and 48 months, mental health of children in the treatment group improved by 0.13 and 0.16 standard deviation points correspondingly with no evidence of mediation. Our findings suggest that anti-poverty programs that aim solely to improve household income may be less advantageous to children's mental health as compared to those that are specifically targeted towards reducing the impact of poverty on children. Further studies using more comprehensive measures of child work and age-appropriate child mental health may shed more light on understanding the link between asset accumulation interventions, child labor and children's mental health.