Environmental health and developmental disabilities: a life span approach

Sexual Offenders With Intellectual Disabilities: An Exploratory Comparison Study in an Incarcerated U.S. Sample

Research indicates that individuals with intellectual disabilities (ID) are overrepresented among sexual offenders, and that those with ID might differ from those without ID in terms of the etiology of offending behavior. Despite this, few studies have explored ID using incarcerated U.S. samples. The present study sought to identify relevant characteristics of this population by comparing individuals with and without ID who are incarcerated in the U.S. for sexual offenses. Archival records for 3,066 participants were used to determine demographic, historical, and offense-related characteristics. Participants with ID, including those with borderline ID, comprised 19.1% of the sample and displayed elevated rates of adverse childhood experiences and psychopathology. Contrary to previous research, participants with ID were no more likely to offend against children than those without ID. These findings help to elucidate the etiology of offending behavior among those with ID and inform on potential targets for intervention.

Persistent organic pollutants at the synapse: Shared phenotypes and converging mechanisms of developmental neurotoxicity

The developing nervous system is sensitive to environmental and physiological perturbations in part due to its protracted period of prenatal and postnatal development. Epidemiological and experimental studies link developmental exposures to persistent organic pollutants (POPs) including polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, polybrominated diphenyl ethers, and benzo(a)pyrene to increased risk for neurodevelopmental disorders in children. Mechanistic studies reveal that many of the complex cellular processes that occur during sensitive periods of rapid brain development are cellular targets for developmental neurotoxicants. One area of research interest has focused on synapse formation and plasticity, processes that involve the growth and retraction of dendrites and dendritic spines. For each chemical discussed in this review, we summarize the morphological and electrophysiological data that provide evidence that developmental POP exposure produces long-lasting effects on dendritic morphology, spine formation, glutamatergic and GABAergic signaling systems, and synaptic transmission. We also discuss shared intracellular mechanisms, with a focus on calcium and thyroid hormone homeostasis, by which these chemicals act to modify synapses. We conclude our review highlighting research gaps that merit consideration when characterizing synaptic pathology elicited by chemical exposure. These gaps include low-dose and nonmonotonic dose-response effects, the temporal relationship between dendritic growth, spine formation, and synaptic activity, excitation-inhibition balance, hormonal effects, and the need for more studies in females to identify sex differences. By identifying converging pathological mechanisms elicited by POP exposure at the synapse, we can define future research directions that will advance our understanding of these chemicals on synapse structure and function.

Characterizing the Neurodevelopmental Pesticide Exposome in a Children's Agricultural Cohort

The exposome provides a conceptual model for identifying and characterizing lifetime environmental exposures and resultant health effects. In this study, we applied key exposome concepts to look specifically at the neurodevelopmental pesticide exposome, which focuses on exposures to pesticides that have the potential to cause an adverse neurodevelopmental impact. Using household dust samples from a children's agricultural cohort located in the Yakima Valley of Washington state, we identified 87 individual pesticides using liquid chromatography-tandem mass spectrometry. A total of 47 of these have evidence of neurotoxicity included in the Environmental Protection Agency (EPA) (re)registration materials. We used a mixed effects model to model trends in pesticide exposure. Over the two study years (2005 and 2011), we demonstrate a significant decrease in the neurodevelopmental pesticide exposome across the cohort, but particularly among farmworker households. Additional analysis with a non-parametric binomial analysis that weighted the levels of potentially neurotoxic pesticides detected in household dust by their reference doses revealed that the decrease in potentially neurotoxic pesticides was largely a result of decreases in some of the most potent neurotoxicants. Overall, this study provides evidence that the neurodevelopmental pesticide exposome framework is a useful tool in assessing the effectiveness of specific interventions in reducing exposure as well as setting priorities for future targeted actions.

The attention set-shifting test is sensitive for revealing sex-based impairments in executive functions following developmental lead exposure in rats

The literature on lead (Pb) exposure has focused in large part on hippocampal-based learning and memory deficits, although frontoexecutive dysfunctions are known to exist in Pb-exposed humans. This study examined the effects of perinatal (PERI) and early postnatal (EPN) developmental low-level Pb-exposures in rats on frontoexecutive functions, using the Attention Set-Shift Test (ASST). Control males and females performed the ASST similarly. Male EPN rats had difficulty with simple discrimination (SD) of odors and failed to complete the compound discrimination (CD) stage of the ASST. All other Pb-exposed rats completed the training and testing. Male PERI rats performed worse on the SD, intradimensional (ID), and intradimensional-reversal (ID-Rev) ASST stages when compared to male Control rats. Female EPN rats performed similar to Controls on the ID-Rev rats, whereas PERI rats performed better the trials-to-criterion on the ID-Rev than EPN and Control rats. Pb-exposed female rats had significant difficulty performing the ED/ED-Rev stages, with the number of trials-to-criterion double that required by Pb-exposed and Control male rats and Control female rats. Together, the ASST results showed that developmental Pb-exposure induces frontoexecutive dysfunction that persists into adulthood, with different sex-based vulnerabilities dependent upon the time-period of neurotoxicant exposure.

Contribution of tobacco smoke exposure to learning disabilities

OBJECTIVE

To investigate the contribution of exposure to prenatal tobacco smoke (PTS) and environmental tobacco smoke (ETS) to parent-reported learning disabilities.

DESIGN

A nationally representative, cross-sectional survey conducted in the United States, the National Health and Nutrition Examination Survey (NHANES) 1999 to 2002, was used to explore the association between reported learning disability and exposure to PTS and ETS.

PARTICIPANTS

Data were analyzed from 5,420 children ages 4 to 15 years old.

METHODS

Secondary data analysis was conducted using logistic regression controlling for a number of potential confounders and covariates.

RESULTS

Overall, 10.6% of children had a parent-reported learning disability (LD), exceeding previous estimates. Exposure to PTS (odds ratio [OR] = 1.6) and ETS (OR = 1.6) were significantly associated with increased odds for LD in children, with a greater odds noted (OR = 2.6) when exposed to PTS and ETS.

CONCLUSION

Exposure to tobacco smoke significantly increases the odds for children to have a learning disability. Overall, results indicate that if tobacco exposure is causally associated to LD, eliminating exposures could prevent an estimated 750,000 of parent-reported learning disabilities in the United States. Results underscore the need for diligence in the promotion of smoking prevention and cessation efforts.