Occupational exposure to different levels of mixed organic solvents and colour vision impairment

Low-level occupational exposure to BTEX and dyschromatopsia: a systematic review and meta-analysis

Objectives. The present study aimed to assess whether occupational exposure to low concentrations of benzene, toluene, ethylbenzene and xylene (BTEX) is associated with color vision impairment. Methods. We queried PubMed, Scopus, Embase, Web of Science and ProQuest as the main databases, as well as gray literature such as Google Scholar. A random-effects model was used to assess relative risk. A funnel plot was created to assess publication bias. Meta-regression analysis was applied to identify variables that explain the between-study variation in the reported risk estimate. Results. An overall standardized mean difference of 0.529 (95% confidence interval [0.269, 0.788]; p < 0.0001) was obtained in the random-effects model, which corresponded to a medium-size effect. Duration and the levels of exposure to benzene, toluene and xylene were the significant predictors of the magnitude of the combined risk estimate. Chronic exposure to low levels of BTEX was associated with dyschromatopsia determined by the color confusion index. Conclusions. The impairments can occur even at exposures lower than the occupational exposure limits of BTEX. However, there are several flaws in the determination of workers' exposure, which did not allow to establish how low a level of these chemicals can cause color vision impairment.

Risk assessment of chemical mixtures by benchmark dose-principle component analysis approach in occupational exposure

Mixtures of organic solvents are widely used in industrial processes. Risk assessment for chemical co-exposure has always been a challenge in past years. The present study aims to employ principle component analysis (PCA) to produce an entry for benchmark dose approximation in shoemakers based on the color vision effect. A total of 134 subjects consisting of 67 shoemakers and 67 staff workers were employed for Benchmark Dose (BMD) evaluation. Occupational exposure to benzene, toluene, xylene, and n-hexane was evaluated using NIOSH 1501 and OSHA ID-07 methods. The color vision effect was quantified using Lanthony D-15 desaturated test (D-15d). PCA was run for cumulative exposure dose (CED) of the solvents by MATLAB 2018. Finally, the lowest 95% confidence limit of the benchmark dose (BMDL) was determined using US EPA benchmark dose software (BMDS) version 3.2.1. The color confusion index (CCI) level in shoemakers increased from 1 to 1.15 by a median of 1.07. There was a significant difference in the CCI level (p value<0.0001) between exposed and control subjects. The first score of PCA was used as intake dose level (IDL) in solvents co-exposure. Using BMD analysis, the log-logistics model was fitted with a p-value> 0.1 and the lowest BMDL level. BMDL level was evaluated at 1.63, 10.25, 2.21, and 3.35 ppm for benzene, toluene, xylene, and n-hexane, respectively. The results showed a risk of color vision effect with co-exposure to solvents at different levels in the occupational exposure standards. In conclusion BMDL-PCA approach has been suggested for the risk assessment of chemical co-exposure.

The relationship between occupational exposure to organic solvents and metabolic syndrome in petroleum refinery workers in Tehran, Iran

AIMS

The rising prevalence of metabolic syndrome has made it a major health concern. Chronic occupational exposure to organic solvents affects different systems of the body. This study aimed to investigate the association between exposure to organic solvents and the prevalence of metabolic syndrome in petroleum refinery workers.

METHOD

This study was conducted in 2019-2020 on workers employed in an Iranian petroleum refinery. The demographic and occupational information on the participants was obtained using the interview method. Their height, weight, and blood pressure were measured by the occupational health team, and fasting blood samples were taken from them to measure the paraclinical parameters.

RESULTS

In this study, 1009 petroleum refinery workers were analyzed. The prevalence of metabolic syndrome in workers was 20.1% and it was about two times higher in exposed workers (CI 95%: 1.61-3.35) compared to non-exposed ones. Factors associated with the prevalence of metabolic syndrome include age, higher BMI, exercise, and longer exposure to organic solvents.

CONCLUSION

Findings of this study suggested that exposure to organic solvents is associated with increased prevalence of metabolic syndrome (the highest association was observed with elevated serum triglycerides). Besides, longer exposure to organic solvents increased the risk of developing metabolic syndrome.

Occupational exposure evaluation of Brazil university community to the volatile organic compounds

Occupational exposure to volatile organic compounds (VOC) might generate serious worker health damages. Therefore, biological monitoring is essential to evaluate exposure biomarkers from highly toxic chemicals, ensuring better attention to the worker health. In this study was developed and validated a bioanalytical method based on high-performance liquid chromatography coupled to photodiode array (HPLC-PDA) for the quantification of VOC biomarkers in urine samples from Federal University of Goias (UFG) workers. Samples were collected from 30 occupationally exposed subjects after application of a questionnaire survey. The following biomarkers hippuric acid, methyl-hippuric acid, mandelic acid, phenylglyoxylic acid and phenol were quantified, representing exposition to toluene, xylene, styrene, ethylbenzene, benzene and phenol solvents, respectively. Hippuric acid levels were found close to or above the reference values, although a subject had levels higher than preconized by Biological Limit Values (BLV) guideline of 4.0 mg/g creatinine. Five subjects had 3 and 4-methylhippuric acid ranging from 0.1 to 1.0 mg/g creatinine. These results indicate a moderate to high VOC exposure from UFG workers. Multivariate analysis generated four clusters and indicated that histotechnicians and graphic workers need especial attention on occupational VOC exposure. The results from this study reinforce the need for reliable methods able to the biological monitoring as an important tool for assessing occupational exposure.

Inside-tube solid-phase microextraction as an interlink between solid-phase microextraction and needle device for n-hexane evaluation in air and urine headspace

Monitoring the trace amount of chemicals in various samples remains a challenge. This study was conducted to develop a new solid-phase microextraction (SPME) system (inside-tube SPME) for trace analysis of n-hexane in air and urine matrix. The inside-tube SPME system was prepared based on the phase separation technique. A mixture of carbon aerogel and polystyrene was loaded inside the needle using methanol as the anti-solvent. The air matrix of n-hexane was prepared in a Tedlar bag, and n-hexane vapor was sampled at a flow rate of 0.1 L/min. Urine samples spiked with n-hexane were used to simulate the sampling method. The limit of detection using the inside-tube SPME was 0.0003 μg/sample with 2.5 mg of adsorbent, whereas that using the packed needle was 0.004 μg/sample with 5 mg of carbon aerogel. For n-hexane analysis, the day-to-day and within-day coefficient variation were lower than 1.37%, with recoveries over 98.41% achieved. The inside-tube SPME is an inter-link device between two sample preparation methods, namely, a needle trap device and an SPME system. The result of this study suggested the use of the inside-tube SPME containing carbon aerogel (adsorbent) as a simple and fast method with low cost for n-hexane evaluation.

The prevalence of color vision deficiency in the northeast of Iran

PURPOSE

To determine the prevalence of color vision deficiency (CVD) in the northeast of Iran.

METHODS

This cross-sectional, population-based study was conducted in Mashhad, in the northeast of Iran. Multistage cluster sampling was used for selecting the participants. After preliminary screening, the subjects underwent a complete ophthalmic examination. The examination included the measurement of visual acuity, refraction, and slit-lamp biomicroscopy. The Farnsworth D-15 test was used to detect CVD. The color vision test was done with the best optical correction.

RESULTS

Of the 4453 invitees, 3132 participated in the study (response rate: 70.4%). The overall prevalence of CVD in this study was 13.93% [95% confidence interval (CI): 12.44-15.41]. The prevalence of CVD in males and females was 15.85% (95% CI: 13.26-18.44) and 12.96% (95% CI: 11.22-14.71), respectively. The most prevalent types of CVD were tritanopia (6.96%; 95% CI: 5.84-8.08), deuteranopia (3.92%; 95% CI: 3.14-4.70) and tritanomalous (2.21%; 95% CI: 1.55-2.86), respectively. According to the results of logistic regression, the odds of having protanopia were higher in females than males [Odds ratio (OR) = 4.80; 95% CI: 1.20-19.18]. The odds of having deuteranopia were lower in females than males (OR = 0.52; 95% CI: 0.35-0.76). The odds of having CVD were lower in 16-30 (OR = 0.52; 95% CI: 0.37-0.73) and higher in 46-60 (OR: 1.41; 95% CI: 1.01-1.97) year age groups compared to 7-15 year age group. The odds of having tritanopia in 16-30 and 46-60 year age groups was 0.56 (95% CI: 0.35-0.90) and 1.79 (95% CI: 1.19-2.67) compared to 7-15 year age groups, respectively.

CONCLUSION

The prevalence of CVD was high in this study, especially in males and people over 46 years of age. Planning for involvement of ocular disease control programs in health care systems can be helpful in the reduction of CVD and improving the quality of life in affected patients.

Evaluation of occupational exposure to different levels of mixed organic solvents and cognitive function in the painting unit of an automotive industry

Background: The cognitive function could be affected following exposure to organic solvents.The purpose of this study was to examine the cognitive performance of workers exposed to different levels of organic solvents in a painting unit of an automotive industry. Methods: This case-control study was conducted, in 2017, on 121 and 111 workers from the painting and assembly units of an automotive industry as the case and control groups,respectively. Exposure of workers to organic solvents were determined according to National Institute for Occupational Safety and Health (NIOSH) method. The cognitive performance of the studied population was evaluated by the computerized tests. Results: The obtained scores of the N-Back in 1 and 2 blocks and the simple reaction time tests(SRTTs) were significantly differed in the exposed group (p<0.05). No significant difference was observed between case and control groups in the Stroop test score (p> 0.05). Moreover, a significant relationship between the hazard quotient and the cognitive function test scores were observed except the Stroop test. Conclusion: Exposure to organic solvents affect the cognitive functions even below the Occupational Exposure Limits (OELs). Moreover, workers with high exposure levels of organic solvents had highest risk of poor memory and reaction time.

Impaired colour vision in workers exposed to organic solvents: A systematic review

OBJECTIVE

To evaluate recent evidence concerning the relationship between the exposure to organic solvents and the impairment of colour vision.

METHODS

A bibliographic search was conducted for scientific papers published in the last 15 years, in the LILACS, PubMed, Science Direct, EBSCO, and Cochrane databases that included observational studies assessing the relationship between impairment in colour vision and exposure to organic solvents.

RESULTS

Eleven studies were selected that were performed on an economically active population and used the Lanthony D-15 desaturated test (D-15d), measured the exposure to organic solvents, and included unexposed controls. It was found that there is a statistically significant relationship between the exposure to organic solvents and the presence of an impairment in colour vision.

CONCLUSIONS

The results support the hypothesis that exposure to organic solvents could induce acquired dyschromatopsia. The evaluation of colour vision with the D-15d test is simple and sensitive for diagnosis. More studies need to be conducted on this subject in order to better understand the relationship between impaired colour vision and more severe side effects caused by this exposure.

Exposición a COVs en fábricas de muebles de dos poblaciones del norte de Colombia

<p><strong>Objetivos</strong> Evaluar la exposición a compuestos orgánicos volátiles (COVs) en trabajadores de fábricas artesanales de mueblesde dos poblaciones de Sucre (Sincelejo y Sampués), Norte de Colombia. Determinar posibles signos y/o síntomas relacionados con la exposición a estos contaminantes.</p><p><strong>Métodos </strong>Estudio transversal analíticocon aplicación de una encuesta. La población objetivo estuvo conformada por 66 individuos, 41 expuestos y 25 controles. Se tomaron muestras personales para las concentraciones de benceno, tolueno, etilbenceno y xilenos (en ambos grupos) y se contrastó con posibles efectos en la salud atribuidos a estos contaminantes.</p><p><strong>Resultados </strong>Las concentraciones de benceno, tolueno y m/p-xileno fueron mayores en el grupo expuesto (9,5 mg/m³, 8,1 mg/m³ y 12,1 mg/m³) en comparación con el grupo control(0,2 mg/m³, 0,3 mg/m³ y 0,03 mg/m³).Dolor muscular 82,9 % (RP=3,8; IC95%:1,2-11,8) y somnolencia 65,9 % (RP=4,9; IC95%:1,7-14,7)estuvieron asociados a mayor exposición (p&lt; 0,05). Factores como el uso de mezclas solventes (thinner) en el trabajo y el tráfico vehicularpueden contribuir a estos resultados.</p><p><strong>Conclusiones </strong>La contribución de diversas fuentes aumenta la exposición personal a los COVs, de los trabajadores de las fábricas artesanales de muebles en el Norte de Colombia. Adicionalmente, el uso excesivo de estos compuestos puede estar generando efectos adversos en la salud de los trabajadores.</p>

Retinal and visual system: occupational and environmental toxicology

Occupational chemical exposure often results in sensory systems alterations that occur without other clinical signs or symptoms. Approximately 3000 chemicals are toxic to the retina and central visual system. Their dysfunction can have immediate, long-term, and delayed effects on mental health, physical health, and performance and lead to increased occupational injuries. The aims of this chapter are fourfold. First, provide references on retinal/visual system structure, function, and assessment techniques. Second, discuss the retinal features that make it especially vulnerable to toxic chemicals. Third, review the clinical and corresponding experimental data regarding retinal/visual system deficits produced by occupational toxicants: organic solvents (carbon disulfide, trichloroethylene, tetrachloroethylene, styrene, toluene, and mixtures) and metals (inorganic lead, methyl mercury, and mercury vapor). Fourth, discuss occupational and environmental toxicants as risk factors for late-onset retinal diseases and degeneration. Overall, the toxicants altered color vision, rod- and/or cone-mediated electroretinograms, visual fields, spatial contrast sensitivity, and/or retinal thickness. The findings elucidate the importance of conducting multimodal noninvasive clinical, electrophysiologic, imaging and vision testing to monitor toxicant-exposed workers for possible retinal/visual system alterations. Finally, since the retina is a window into the brain, an increased awareness and understanding of retinal/visual system dysfunction should provide additional insight into acquired neurodegenerative disorders.

Color vision impairments among shipyard workers exposed to mixed organic solvents, especially xylene

OBJECTIVES

We evaluated color vision impairment in workers exposed to organic solvents, especially xylene.

METHODS

Three groups of subjects, comprising 63 workers occupationally exposed to organic solvents, 122 non-exposed workers in the same industry, and 185 subjects from the general population as controls, were evaluated for color vision. Exposure to solvents was indirectly evaluated by measuring the concentration of a urinary metabolite. Color vision was assessed using the Lanthony Desaturated 15-hue (Lanthony D-15) panel.

RESULTS

Color confusion index (CCI) values in the exposed group were significantly higher than in the non-exposed workers or the general population, after adjustment for age and education, and significantly correlated with the concentration of methylhippuric acid. Color vision impairments were detected more frequently among the exposed group, and the most common types were type III and complex impairments. The rate of type III impairments was 9.52% in the exposed group, 1.64% in the non-exposed group, and 1.62% in the general population.

CONCLUSION

Our results support the hypothesis that acquired color vision impairments could be induced by exposure to xylene. Testing for color vision impairment is a relatively simple, non-invasive and sensitive diagnostic method for relatively low-level exposures to xylene.

Effects of Exposure to Mixed Organic Solvents on Blood Pressure in Non-Smoking Women Working in a Pharmaceutical Company

Some studies suggest that exposure to industrial solvents can affect blood pressure. The objective of this study was to investigate the effect of a mixture of organic solvents on blood pressure in women working in a pharmaceutical company in Iran. Four hundred and thirty-three women were included in the study. Women working in packing units (group 1) were not exposed to the mixture of organic solvents, women in new laboratory units (group 2) were exposed to the mixture within the permitted range and women working in old laboratory units (group 3) were exposed to the mixture above the permitted limit. We compared systolic and diastolic blood pressures (SBP & DBP) and prevalence of hypertension and pre-hypertension among groups. The results revealed a significant difference in SBP and pre-hypertension (p<0.001) and hypertension (p<0.05) prevalence between the exposed and the control group, but DBP did not differ significantly. Logistic regression analysis showed a significant association between hypertension and exposure to mixed solvents. Odds ratio for hypertension in the group 2 and group 3 (exposed) workers was 2.36 and 3, respectively, compared to controls. Our results suggest that exposure to a mixture of organic solvents may increase SBP and hypertension and pre-hypertension prevalence in drug manufacture workers. Therefore, more attention should be paid to workers that work in such settings by periodically measuring blood pressure and implementing accurate and comprehensive programs to reduce exposure to organic solvents.