Exposure to organic solvents used in dry cleaning reduces low and high level visual function

Pupil size change in agricultural workers exposed to pesticides

CLINICAL RELEVANCE

Pupil size evaluation using clinical examination may be important for detecting and monitoring individuals at risk of neurotoxic effects from chemical exposure, as it may enable early intervention and the implementation of preventive measures.

BACKGROUND

This work aimed to investigate the association between pesticide exposure and pupil size. Pupil size is regulated by muscarinic and nicotinic receptors, and it is well-established that common pesticide chemicals disrupt this regulation.

METHODS

Twenty agricultural workers exposed to pesticides, and twenty participants not exposed, underwent visual screening, and pupil size evaluation under mesopic and photopic conditions. Additionally, signs of neurotoxicity and pesticide exposure in both groups were evaluated using the modified version of the neurotoxic symptoms questionnaire (Q16) and measuring cholinesterase (AChE) levels in blood, respectively.

RESULTS

Agricultural workers exposed to pesticides had a score indicating medium-high level of neurotoxicity (49.85 (SD ± 8.94)) which was significantly higher (t (36) = 7.659, p ≤ 0.0001) than non-exposed participants who had low levels of neurotoxicity (27.25 SD ± 8.86). There was a significant difference in pupil size (mm) under mesopic (t (19) 4.42 p = 0.003) and scotopic (t (19) 4.63, p = 0.0002) conditions between the two groups. Additionally, there was a significant difference in AChE blood levels (t (19) 2.94 p = 0.008) between exposed and non-exposed participants, indicating that exposed workers had low levels of this enzyme (average exposed group 3381 U/L (SD ± 1306)) compared to the non-exposed group (average non-exposed group 4765 U/L (SD ± 1300)). A significant negative correlation between AChE levels, years of exposure, and pupil size was found. The latter finding importantly showed that smaller pupils are associated with the accumulation of acetylcholine or a decrease in the activity of the enzyme AChE.

CONCLUSION

Pupil size of agricultural workers exposed to pesticides can be abnormal and is associated with neurotoxicity as indicated by symptomatology and cholinesterase levels. Evaluation of pupil size may be useful for clinically detecting neurotoxicity.

Impairment of visual and neurologic functions associated with agrochemical use

To determine whether exposure to occupational levels of agrochemicals is associated with a range of low- (contrast and colour) and higher-level visual functions, particularly the detection of global form and motion coherence. We compared the performance of workers exposed to occupational levels of pesticides and non-exposed individuals on visual tasks that measured colour discrimination (Farnsworth Munsell 100 and Lanthony D15 desaturated) and the contrast sensitivity function (1-16 cpd). Global form and motion detection thresholds were measured using Glass-pattern and global dot motion stimuli. Neurotoxicity symptoms and biological markers associated with pesticide exposure were quantified using the Q16 modified questionnaire and via tests for levels of acetylcholinesterase in blood and substance P from the tear film, respectively. Workers exposed to pesticides had significantly more neurotoxic symptoms than non-exposed workers. No significant difference between groups for acetylcholinesterase levels was found, but there was a significant group difference in Substance P. The exposed group also had significantly poorer contrast sensitivity, colour discrimination and higher coherence detection thresholds for global form and motion perception. Exposure to occupational levels of agrochemicals in workers with signs of neurotoxicity is associated with low and high visual perception deficits.

Smoking, urinary cotinine levels and incidence of visual impairment

The longitudinal relationship between smoking status and risk of developing visual impairment (VI) remains unclear. We examined the relationship of smoking status and urinary cotinine level, an objective measure of smoking, with incidence of VI. This cohort study included 279,069 individuals free of VI who were followed for up to 8.8 years (median 4.8 years). VI was defined as when bilateral visual acuity was worse than 0.5 (cutoffs of 0.3 Logarithm of the Minimum Angle of Resolution). During 1,324,429.8 person-years of follow-up, 7852 participants developed new-onset bilateral VI. Self-reported current smoking status was associated with increased risk of developing VI in both men and women, with a stronger association in women (P for interaction = 0.01). Multivariable adjusted hazard ratios (95% confidence intervals) for incident VI comparing current smokers to never-smokers were 1.14 (1.04–1.25) in men and 1.52 (1.28–1.80) in women. Urinary cotinine levels of ≥ 100 ng/ml were significantly associated with increased risk of incident VI, and these associations remained when introducing changes in urinary cotinine and other confounders during follow-up as time-varying covariates. Cigarette smoking assessed based on self-report and urinary cotinine level was associated with increased incidence of VI. Our findings identify smoking as an independent risk factor for VI.

Prenatal exposure to glycol ethers and visual contrast sensitivity in 6-year-old children in the PELAGIE mother-child cohort

BACKGROUND

Maternal occupational exposure to organic solvents during pregnancy has been associated with decreased visual function in offspring. Glycol ethers (GEs) belong to oxygenated solvents and are widely used both in occupational and domestic contexts.

OBJECTIVES

We aimed to assess associations between prenatal GEs exposure and contrast sensitivity in children.

METHODS

Six GE alkoxy carboxylic acidic metabolites (methoxyacetic acid [MAA], ethoxyacetic acid [EAA], ethoxyethoxyacetic acid [EEAA], butoxyacetic acid [BAA], phenoxyacetic acid [PhAA], and 2-methoxypropionic acid [2-MPA]) were measured in first morning void urine samples collected from 220 early-pregnancy women, in the mother-child PELAGIE cohort (France). Trained investigators administered the Functional Acuity Contrast Test (FACT) to the 6-year-old children, providing scores for 5 spatial frequencies (1.5-18 cycles per degree (cpd)). We standardized biomarker urinary concentrations on urine sampling conditions. Values below the LOD were imputed based on log-normal distribution, generating five datasets for multiple imputation. Linear regression models were adjusted for potential confounders.

RESULTS

GE metabolites were detected in 70-98% of maternal urine samples. Phenoxyacetic acid (PhAA) had the highest median concentration (0.33 mg/L), and 2-methoxypropionic acid (2-MPA) the lowest (0.01 mg/L). Children with higher prenatal PhAA concentrations had poorer FACT scores at various spatial frequencies (fourth vs. first quartile: β_18cpd = -0.90 (95% confidence interval CI = -1.64, -0.16), β_12cpd = -0.92 (95%CI = -1.55, -0.29) and β_1.5cpd = -0.69 (95%CI = -1.19, -0.20)). The 2-MPA log-scale concentration was negatively associated with the FACT score at the 3-cpd stimulus.

DISCUSSION

PhAA is the metabolite of ethylene glycol monophenyl ether present in many cosmetics. 2-MPA is the metabolite of an isomer of propylene glycol methyl ether commonly present in household and industrial cleaning products. Although evidence of biological plausibility is lacking, the study suggests adverse impact of ubiquitous prenatal exposure to some GE on visual functioning among children.

Ocular surface and tear film changes in workers exposed to organic solvents used in the dry-cleaning industry

Workers in the dry-cleaning industry are exposed to organic solvents that may cause eye irritation and tear film changes. Objective To quantify changes in the ocular surface and tear film in dry cleaners exposed to organic solvents and associate these changes with ocular irritation as reported in a symptom questionnaire for dry eye diagnosis. Methods This was a case and control study in which the characteristics and eye-irritation symptoms were compared between two groups of 62 participants that were either exposed or not exposed to organic solvents. A general optometric examination and the following test were performed: lipid interferometry, Lissamine Green Stain, tear breakup time, Schirmer I, conjunctival impression cytology and the Donate dry eye symptoms questionnaire. Results Sixty-five percent of exposed workers obtained a higher score than 13 on the Donate dry eye symptoms questionnaire which indicated the presence of more irritation symptoms than those in the non- exposed group. A Chi-square analysis indicated the exposed group reported significantly higher incidences (P <0.005) for eye irritation symptoms of sandy sensation; tearing eyes sensation; foreign body sensation; tearing; dry eye; dryness; eyestrain and heavy eyelids. A Mann Whitney-U indicated greater severity only for symptoms relating to dry eye; sandy sensation; foreign body sensation, tearing; tearing eyes and dryness. There was a statistically significant difference (P <0.05) for Schirmer I; tear break up time; and the ocular surface assessed with Lissamine green staining and conjunctival impression cytology between groups. A reduction in the thickness of the lipid layer in the exposed group compared to the non-exposed group was observed. Surprisingly, clinical test outcomes were not significantly correlated with dry eye symptoms nor years of exposure. Conclusion Workers in the dry-cleaning industry exposed to organic solvents are associated with changes in ocular surface and tear film generating irritation symptoms commonly present in evaporative dry eye.

Peptidomic analysis of zebrafish embryos exposed to polychlorinated biphenyls and their impact on eye development

Polychlorinated biphenyls (PCBs), a class of persistent organic pollutant, are closely related to abnormal eye development in children. However, little is known regarding the role of peptides in the development of PCB-induced ocular dysplasia. To characterize the nature of PCB exposure on peptides involved in the development of the ocular system, we used liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) to detect differential expression of peptides between normal and PCB-exposed zebrafish embryos. A total of 7900 peptides were analyzed, 90 of which were differentially expressed, with 29 being up-regulated and 61 down-regulated. These peptides were investigated using ingenuity pathway analysis (IPA) and gene ontology (GO) analysis to explore their role in eye development. This study identified 18 peptides associated with the development of the optic nerve and ocular system in the PCB-exposure group, as well as 10 peptides that are located in the functional domain of their precursor proteins. These peptides provide potential biomarkers for the treatment of ocular dysplasia caused by PCBs and may help us understand the mechanism of abnormal eye development caused by organic pollutants.

Chronic Exposure to Solvents Among Construction Painters: Reductions in Exposure and Neurobehavioral Health Effects

OBJECTIVE

The aim of this study was to assess the neurobehavioral effects of lifetime solvent exposure by comparing the performance of painters and demographically comparable controls.

METHODS

Performance of exposed painters (N = 133) was compared with unexposed tapers, glaziers, or carpenters (N = 78) on the following domains: motor/perceptual speed, visual contrast, attention, working memory/planning, and visual and verbal memory. Lifetime exposure was estimated with questionnaires, field measurements, and paint composition.

RESULTS

After controlling for confounders, lifetime solvent exposure did not predict reduction in performance for overall domains of function. Lifetime solvent exposures predicted subtle alterations for individual tests of verbal learning, motor coordination, and visuospatial accuracy.

CONCLUSION

Concentrations of solvents in paints have steadily declined during the working lifetime of subjects in this study. Although reduced performance was observed on individual tests, these alterations were not consistent across tests and unlikely to be of clinical significance.

Chronic Organic Solvent Exposure Changes Visual Tracking in Men and Women

Organic solvents can change CNS sensory and motor function. Eye-movement analyses can be important tools when investigating the neurotoxic changes that result from chronic organic solvent exposure. The current research measured the eye-movement patterns of men and women with and without histories of chronic organic solvent exposure. A total of 44 volunteers between 18 and 41 years old participated in this study; 22 were men (11 exposed and 11 controls), and 22 were women (11 exposed and 11 controls). Eye movement was evaluated using a 250-Hz High-Speed Video Eye Tracker Toolbox (Cambridge Research Systems) via an image of a maze. Specific body indices of exposed and non-exposed men and women were measured with an Inbody 720 to determine whether the differences in eye-movement patterns were associated with body composition. The data were analyzed using IBM SPSS Statistics version 20.0.0. The results indicated that exposed adults showed significantly more fixations (t = 3.82; p = 0.001; r = 0.51) and longer fixations (t = 4.27; p = 0.001, r = 0.54) than their non-exposed counterparts. Comparisons within men (e.g., exposed and non-exposed) showed significant differences in the number of fixations (t = 2.21; p = 0.04; r = 0.20) and duration of fixations (t = 3.29; p = 0.001; r = 0.35). The same was true for exposed vs. non-exposed women, who showed significant differences in the number of fixations (t = 3.10; p = 0.001; r = 0.32) and fixation durations (t = 2.76; p = 0.01; r = 0.28). However, the results did not show significant differences between exposed women and men in the number and duration of fixations. No correlations were found between eye-movement pattern and body composition measures (p > 0.05). These results suggest that chronic organic solvent exposure affects eye movements, regardless of sex and body composition, and that eye tracking contributes to the investigation of the visual information processing disorders acquired by workers exposed to organic solvents.