Interactions of agricultural pesticide use near home during pregnancy and adverse childhood experiences on adolescent neurobehavioral development in the CHAMACOS study

Pesticide mediated silent neurotoxicity and its unmasking: An update on recent progress

Being human's one of the most protected organs, brain is yet most vulnerable to xenobiotics exposure. Though pesticide-mediated neurotoxicity is well-explored, the fraternity of neurotoxicologists is less focused on the phenomenon of "silent" or "clinically undetectable" neurotoxicity. Silent neurotoxicity defines continual trivial changes in the nervous system that do not manifest any overt signs of toxicity unless unmasked by any natural or experimental event. Although this perception is not novel, insufficient experimental and epidemiological evidence makes it an outlier among toxicological research. A report in 2016 highlighted the need to investigate silent neurotoxicity and its potential challenges. The limited existing experimental data unveiled the unique responsiveness of neurons following silent neurotoxicity unmasking. Concerned studies have shown that low-dose developmental exposure to pesticides sensitizes the nigrostriatal dopaminergic system towards silent neurotoxicity, making it vulnerable to advanced cumulative neurotoxicity following pesticide challenges later in life. Therefore, conducting such studies may explain the precise etiology of pesticide-induced neurological disorders in humans. With no updates on this topic since 2016, this review is an attempt to acquaint the neurotoxicologist with silent neurotoxicity as a serious threat to human health, and proof-of-concept through a narrative using relevant published data so far with future perspectives.

Disparities in Toxic Chemical Exposures and Associated Neurodevelopmental Outcomes: A Scoping Review and Systematic Evidence Map of the Epidemiological Literature

BACKGROUND

Children are routinely exposed to chemicals known or suspected of harming brain development. Targeting Environmental Neuro-Development Risks (Project TENDR), an alliance of > 50 leading scientists, health professionals, and advocates, is working to protect children from these toxic chemicals and pollutants, especially the disproportionate exposures experienced by children from families with low incomes and families of color.

OBJECTIVE

This scoping review was initiated to map existing literature on disparities in neurodevelopmental outcomes for U.S. children from population groups who have been historically economically/socially marginalized and exposed to seven exemplar neurotoxicants: combustion-related air pollution (AP), lead (Pb), mercury (Hg), organophosphate pesticides (OPs), phthalates (Phth), polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyls (PCBs).

METHODS

Systematic literature searches for the seven exemplar chemicals, informed by the Population, Exposure, Comparator, Outcome (PECO) framework, were conducted through 18 November 2022, using PubMed, CINAHL Plus (EBSCO), GreenFILE (EBSCO), and Web of Science sources. We examined these studies regarding authors' conceptualization and operationalization of race, ethnicity, and other indicators of sociodemographic and socioeconomic disadvantage; whether studies presented data on exposure and outcome disparities and the patterns of those disparities; and the evidence of effect modification by or interaction with race and ethnicity.

RESULTS

Two hundred twelve individual studies met the search criteria and were reviewed, resulting in 218 studies or investigations being included in this review. AP and Pb were the most commonly studied exposures. The most frequently identified neurodevelopmental outcomes were cognitive and behavioral/psychological. Approximately a third (74 studies) reported investigations of interactions or effect modification with 69% (51 of 74 studies) reporting the presence of interactions or effect modification. However, less than half of the studies presented data on disparities in the outcome or the exposure, and fewer conducted formal tests of heterogeneity. Ninety-two percent of the 165 articles that examined race and ethnicity did not provide an explanation of their constructs for these variables, creating an incomplete picture.

DISCUSSION

As a whole, the studies we reviewed indicated a complex story about how racial and ethnic minority and low-income children may be disproportionately harmed by exposures to neurotoxicants, and this has implications for targeting interventions, policy change, and other necessary investments to eliminate these health disparities. We provide recommendations on improving environmental epidemiological studies on environmental health disparities. To achieve environmental justice and health equity, we recommend concomitant strategies to eradicate both neurotoxic chemical exposures and systems that perpetuate social inequities. https://doi.org/10.1289/EHP11750.

Dampened psychobiological responses to stress and substance use in adolescence

Substance use increases throughout adolescence, and earlier substance use may increase risk for poorer health. However, limited research has examined whether stress responses relate to adolescent substance use, especially among adolescents from ethnic minority and high-adversity backgrounds. The present study assessed whether blunted emotional and cortisol responses to stress at age 14 related to substance use by ages 14 and 16, and whether associations varied by poverty status and sex. A sample of 277 Mexican-origin youth (53.19% female; 68.35% below the poverty line) completed a social-evaluative stress task, which was culturally adapted for this population, and provided saliva samples and rated their anger, sadness, and happiness throughout the task. They also reported whether they had ever used alcohol, marijuana, cigarettes, and vaping of nicotine at age 14 and again at age 16. Multilevel models suggested that blunted cortisol reactivity to stress was associated with alcohol use by age 14 and vaping nicotine by age 16 among youth above the poverty line. Also, blunted sadness and happiness reactivity to stress was associated with use of marijuana and alcohol among female adolescents. Blunted stress responses may be a risk factor for substance use among youth above the poverty line and female adolescents.

Changes in Young Latino Adults' Depressive and Anxious Symptoms During the COVID-19 Pandemic and Related Stressors

PURPOSE

Youth are vulnerable to poor mental health outcomes during emerging adulthood. This study examined COVID-19 pandemic effects among young Latino adults and changes in anxiety and depressive symptoms.

METHODS

Using data from 309 individuals, predominantly of Mexican origin, we examined anxiety and depressive symptoms (before and during COVID) to determine whether mental health worsened during this period. We also examined associations between specific pandemic-related stressors and mental health. Analyses used paired T-tests and linear regressions. Participant sex was included as a moderator. We corrected for multiple comparisons using the Benjamini-Hochberg method.

RESULTS

During the 2-year time period, depressive symptoms increased while anxiety symptoms decreased. There were no significant stressor by sex interactions; however, exploratory analyses signaled that pandemic-related stressors had stronger mental health effects for young women.

DISCUSSION

Young adults' depressive and anxiety symptoms changed during the pandemic, and pandemic-related stressors were associated with increases in mental health symptoms.

Per- and polyfluoroalkyl substances and psychosocial stressors have a joint effect on adverse pregnancy outcomes in the Atlanta African American Maternal-Child cohort

BACKGROUND

African Americans (AAs) experience high rates of adverse pregnancy outcomes relative to Whites. Differential in utero exposure to environmental chemicals and psychosocial stressors may explain some of the observed health disparities, as exposures to per- and polyfluoroalkyl substances (PFAS) and experiences of discrimination have been linked to adverse birth outcomes. Few studies have examined chemicals and non-chemical stressors together as an exposure mixture, which may better reflect real-life exposure patterns. Here, we adapted methods designed for the analysis of exposure mixtures to examine joint effects of PFAS and psychosocial stress on birth outcomes among AAs.

METHODS

348 participants from the Atlanta African American Maternal-Child cohort were included in this study. Four PFAS were measured in first trimester serum samples. Self-report questionnaires were administered during the first trimester and were used to assess psychosocial stress (perceived stress, depression, anxiety, gendered racial stress). Quantile g-computation and Bayesian kernel machine regression (BKMR) were used to estimate the joint effects between PFAS and psychosocial stressors on gestational age at delivery and birthweight for gestational age z-scores. All models were adjusted for maternal education, maternal age, parity, and any alcohol, tobacco and marijuana use.

RESULTS

Our analytic sample included a socioeconomically diverse group of pregnant women, with 79 % receiving public health insurance. In quantile g-computation models, a simultaneous one-quartile increase in all PFAS, perceived stress, depression, anxiety, and gendered racial stress was associated with a reduction in birthweight z-scores (mean %change per quartile increase = -0.24, 95 % confidence interval = -0.43, -0.06). BKMR similarly showed that increasing all exposures in the mixture was associated with a modest decrease in birthweight z-scores, but not a reduced length of gestation.

DISCUSSION

Using methods designed for analyzing exposure mixtures, we found that a simultaneous increase in in utero PFAS and psychosocial stressors was associated with reduced birthweight for gestational age z-scores.