Neurological effects
Monday 6 October 2025, 16.00 – 17.30 Fluor
Chairs: Damien McElvenny, Tosca de Crom
Cognitive effects of chronic organophosphate exposure on executive function in workers from Maule Region, Chile
Boris Lucero (presenter)
James Bennion, Maria Teresa Muñoz-Quezada, Tristan Bekinschtein
Abstract
Objective: This study aimed to evaluate the association between chronic exposure to organophosphate pesticides and executive function performance in rural Chilean agricultural workers, using validated neuropsychological assessment and biomarker-based exposure quantification.
Material and Methods: We conducted a longitudinal study (2022–2023) in the Maule region of Chile, comparing agricultural workers with documented occupational pesticide exposure to non-exposed rural controls. Participants (N=80) underwent urine sampling across high and low pesticide seasons to quantify six dialkyl phosphate (DAP) metabolites as biomarkers of organophosphate exposure. Executive function was assessed with the Ineco Frontal Screening (IFS), a validated battery covering working memory, inhibitory control, abstraction, and flexibility. Data were analyzed using multiple linear regressions and generalized estimating equations (GEEs), controlling for age, sex, and education.
Results: Urinary metabolite levels did not differ significantly between groups; however, within-group analyses revealed meaningful dose-response relationships. In the exposed group, higher levels of diethyl metabolites were significantly associated with lower IFS scores in both years (β = -73.61 and -79.20, p < .01). GEEs across years found small but significant negative effects of dimethyl metabolites on IFS performance (β = -0.0858, p < .001), although this effect was sensitive to outlier exclusion. Education and age remained strong predictors of executive function, but the pesticide effects persisted after adjustment.
Conclusion: Findings suggest that chronic organophosphate exposure is associated with modest but consistent impairments in executive function among rural Chilean workers, even in the absence of significant between-group differences in exposure levels. This highlights the potential impact of environmental and dietary sources of exposure and supports the need for stronger regulation and longitudinal monitoring in low-to-middle-income countries.
Maternal occupational physical and psychosocial exposures during pregnancy in association with neurodevelopmental conditions in children
Fan Wu (presenter)
Libor Šulc, Abid Lashari, Karl Lundin Remnélius, Andrei Pyko, Alicia Nevriana, Claudia Lissåker, Mattias Sjöström, Pernilla Wiebert, , Sven Bölte, Per Gustavsson, Maria Albin, Jenny Selander
Abstract
Objective: To investigate the associations between maternal prenatal occupational exposures to noise, vibration, and psychosocial stressors and the likelihood of children being diagnosed with attention deficit hyperactivity disorder (ADHD) or autism spectrum disorder (autism).
Material and Methods: The birth-register-based FAIR cohort, covering the 2,101,678 children born in 1994–2014 in Sweden, was used. Children’s ADHD and autism diagnoses were identified from the Swedish National Patient Register of 1994–2021. Individual demographic, socioeconomic, and diagnoses data from multiple registers were linked by unique person IDs. Maternal occupational exposures to physical (noise and vibration) and psychosocial factors (decision authority, job demands, and workplace social support) were estimated by linking mothers’ Standard Swedish Occupational Classification Code (SSYK96) at pregnancy to the calendar-time specific Swedish Job-Exposure Matrices. Exclusion criteria included missing SSYK96, self-reported as non-working, or high work-day absence (>90th percentile). Noise and vibration (binary: exposed/non-exposed) and psychosocial factors (quartiles) were analyzed in single-exposure logistic regression models with ADHD/autism, starting unadjusted and incrementally adjusted for: basic covariates (sex, birth year, country of birth, maternal age), maternal smoking, parity, family economy, maternal education, maternal BMI. The same models also analyzed interactions between one physical and one psychosocial exposure (six combinations).
Results: Preliminary results based on 1,607,805 children (2.98% autism, 6.85% ADHD) found small but statistically significant elevations of OR for ADHD and/or autism in children in association with maternal exposure to noise, vibration, lower decision authority, lower social support, and medium-low (quartile-3) demands. High demands were inversely associated with ADHD/autism diagnosis. Significant interactions between noise and psychosocial factors, and between vibration and social support were detected.
Conclusion: Maternal occupational noise, vibration, and psychosocial stressors during pregnancy are in these preliminary findings associated with an increased probability of ADHD or autism diagnoses in children. Analyses are ongoing to assess the genetic contribution to this association.
Occupational exposure to chlorinated solvents and risk of amyotrophic lateral sclerosis: A Chinese case-control study
Jia Nie (presenter)
Jia Nie, Calvin B. Ge, Susan Peters, Nat Rothman, Ruwei Ou, Qianqian Wei , Lingyu Zhang , Yanbing Hou , Qing Lan , Huifang Shang, Roel Vermeulen
Abstract
Objectives: Previous studies on the association between occupational exposure to chlorinated solvents and the risk of amyotrophic lateral sclerosis (ALS) have shown inconsistent results. We aim to examine the association in a Chinese case-control study.
Methods: We conducted a hospital-based case-control study, recruiting 430 newly diagnosed ALS cases and 1,033 controls. Occupational exposure to trichloroethylene (TCE) and perchloroethylene (PCE) was estimated using semi-quantitative job-exposure matrices (JEMs), developed from routine industrial hygiene monitoring datasets, published literature, international JEMs, and expert input. Logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for ALS risk in relation to various exposure metrics, adjusting for age, sex, education, residential distance to hospital, and pesticide exposure.
Results: TCE and PCE exposures were highly correlated (r = 0.93, P < 0.001), and exposure-associated ALS risk showed similar patterns. Ever exposure to TCE was associated with a lower risk of ALS compared to unexposed (OR: 0.55, 95%CI: 0.38-0.79). When cumulative TCE exposure was categorized into quartiles based on the control distribution, adjusted ORs (95%CI) for ALS risk were 0.43 (0.21–0.83), 0.46 (0.20–0.98), 0.38 (0.15–0.82), and 0.89 (0.49–1.56) across increasing quartiles. Exposure-response trend was not significant when excluding non-exposed individuals (Ptrend = 0.143). In sensitivity analyses limited to job titles with higher certainty of TCE exposure, inverse associations remained but were less precise.
Discussions: Our preliminary findings suggest a potential inverse association between occupational chlorinated solvents exposure and ALS risk, particularly at lower exposure levels. However, the lack of a consistent exposure-response and imprecision in sensitivity analyses warrant cautious interpretation. This is the first study to assess lifetime occupational exposure specifically to TCE and PCE and ALS risk in Asian populations using semi-quantitative JEMs. These results contribute to a growing body of evidence on chlorinated solvents-related neurotoxicity.
Occupational exposure to pesticides increases the risk of amyotrophic lateral sclerosis: a meta-analysis
Sabrina Gravel (presenter)
France Labrèche
Abstract
Objective To assess the strength of evidence on the association between occupational exposure to pesticides and the risk of amyotrophic lateral sclerosis (ALS).
Material and Methods A systematic literature search was conducted in nine bibliographic databases for articles published between January 1980 and August 2023. Eligible articles reported on observational studies that presented specific risk estimates for ALS in relation to occupational exposure to pesticides. Evaluation of the quality of studies was carried out using the WHO Risk of bias (RoB) assessment instrument for systematic reviews with the ROBINS-E domains of bias. Adjusted risk estimates were pooled with random-effect models, heterogeneity was assessed using the I² statistic, and publication bias, using funnel plots and Egger’s test.
Results One cohort and eight case-control studies, published between 1997 and 2022 representing a total of 2600 ALS cases, were retained as relevant for meta-analysis, out of 140 initially identified articles. Ever occupational exposure to pesticides was associated with an increased risk of ALS (n=7 studies, odds ratio [OR]=1.5, 95% confidence interval [CI] 1.1-2.1; I²=60%), for all sex combined. With estimates stratified by type of pesticides, the overall OR was 1.3 (n=6, 95%CI 1.0-1.7; I²=13%), with herbicides and insecticides being associated with higher risks (both ORs=1.4) than fungicides (OR=1.2). The exclusion of the cohort study only marginally increased these risk estimates. Ever exposure to high levels of pesticides was associated with a larger risk than exposure to low levels (n=3, OR=2.7, 1.4-5.0 vs. OR=1.9, 1.0-3.7, I2=0%). There was no obvious funnel plot asymmetry and the heterogeneity between studies appeared to be due to differences in study population and the variety of exposure assessment methods.
Conclusion Despite inconsistencies between certain results, and remaining problems with the quality of exposure assessment, the available evidence suggests that occupational exposure to pesticides may increase the risk of SLA.
The impact of maternal occupational exposure on ADHD and autism diagnoses in children
Libor Šulc (presenter)
Libor Šulc, Fan Wu, Abid Lashari, Karl Lundin Remnélius , Andrei Pyko, Alicia Nevriana, Claudia Lissåker, Mattias Sjöström, Pernilla Wiebert, Sven Bölte , Per Gustavsson, Maria Albin, Jenny Selander
Abstract
The incidence of attention deficit hyperactivity disorder (ADHD) and autism has increased in recent years. While there is a consensus that these are largely genetically driven conditions and the increase is primarily attributed to administrative changes, such as broader diagnostic criteria, prenatal factors, like maternal occupational exposure to chemicals, may also play some role. This study investigates the association between such exposures and the diagnosis of ADHD and autism in children. We used a nationwide Swedish register-based cohort covering births from 1994 to 2014. The dataset includes detailed maternal socioeconomic and demographic information and diagnoses made in children later in life. Maternal occupational exposures to 35 chemical agents were assessed from a job-exposure matrix linked to the self-reported occupation at the first prenatal visit (week 10). The study population was stratified by maternal work status during pregnancy (full-time or part-time, accounting for leave of absence). Data were analysed using logistic regression, reporting odds ratios (OR) and confidence intervals. Extensive sensitivity analyses were conducted to test the robustness of the results. In total, 608,862 children of full-time working mothers and 357,119 children of part-time working mothers were included. Preliminary results show an association between ADHD and exposure to gasoline engine exhaust (OR = 2.07 [1.40 – 3.06]), which remained robust across a series of sensitivity analyses (e.g., restriction to non-university educated mothers, first-time mothers). Other associations included exposure to carbon monoxide (OR = 1.45 [1.05 – 2.01]), iron (OR = 1.62 [1.03 – 2.56]), and paper and pulp dust (OR = 1.77 [1.01 – 3.09]). This study provides evidence of an association between exposure to certain chemicals during pregnancy and autism or ADHD diagnoses in children. However, some associations were not robust in sensitivity analyses, and the genetic predispositions were not assessed. Further studies are needed to confirm these associations and clarify the underlying mechanisms.
Work-related risk factors of insomnia: Evidence from population-based panel study
Heejoo Ko (presenter)
Seong-Sik Cho; Mo-Yeol Kang
Abstract
Objectives While many studies have demonstrated the association between work environment and insomnia, comprehensive research examining a wide range of work-related risk factors across the general working population remains limited. This study aimed to explore work-related risk factors for insomnia among Korean workers using population-based panel data.
Material and Methods Data were obtained from the Korean Work, Sleep, and Health Study (2022–2024), comprising 8,976 respondents. Insomnia was assessed using the Insomnia Severity Index. Occupational risk factors–including long working hours, shift work, occupational stress, emotional labor, physical/chemical hazards, and ergonomic strain, were assessed using structured questionnaires. Generalized estimating equation models were applied with adjustments for sociodemographic factors.
Results Working more than 52 hours per week was associated with higher odds of insomnia (OR=1.341,95% CI:1.130–1.591), whereas shift work was not. High occupational stress showed a strong association with insomnia (OR=3.258,95% CI:2.925–3.628), particularly in relation to poor physical environment, high job demand, and high job insecurity. High-risk emotional laborers had increased odds of insomnia compared to low-risk groups (OR=2.633,95% CI:2.219–3.124), especially with emotional dissonance and organizational monitoring. Exposure to physical or chemical hazards was associated with insomnia (OR=1.832,95% CI:1.669–2.010), with notable risks including noise, high temperatures, solvent vapors, and environmental smoking. Ergonomic risk exposures were also associated with insomnia (OR=1.502,95% CI:1.371–1.645), with motorcycle riding, kneeling or squatting posture, and repetitive arm movements showing strong associations. Similar patterns were observed across sex, age, and occupational groups.
Conclusion This study highlights that diverse work-related risk factors contribute to insomnia in workers. Strategies to improve occupational conditions–including reducing work stressors and mitigating physical, chemical, and ergonomic hazards–may be essential components of sleep health promotion. Incorporating occupational history into clinical assessments of insomnia could aid prevention. This research was financially supported by the National Research Foundation of Korea (NRF-2022R1F1A1066498).