Exposure of workers to a mixture of toluene and xylenes. II. Effects

Liver function alterations among workers in the shoe industry due to combined low-level exposure to organic solvents

This study aimed to investigate the potential hepatotoxicity, nephrotoxic, and hematotoxic effects of simultaneous occupational low-level exposure of shoe workers to a mixture of organic solvents. The study included 16 male and 55 female workers and non-exposed subjects (n = 60) in the control group. Along with a standard sets of hematological, liver enzymes (aspartate aminotransferase (AST), alanine aminotransferase (ALT) and gamma-glutamyl transpeptidase (GGT), bilirubin total, bilirubin direct, blood glucose, urea, and creatinine were analyzed in all participants. Indoor air quality was monitored using a Gasmet Dx - 4000 multi-component analyzer. Despite the concentration levels of individual chemicals in shoe production units were below the permissible limits, the equivalent exposure (Em) values calculated based on the American Conference of Governmental Industrial Hygienists (ACGIH) and National Institute of Occupational Safety and Health (NIOSH) occupational exposure limits were higher than 1. Statistically significant increase of biochemical parameters (aspartate aminotransferase (AST), gamma-glutamyl transpeptidase (GGT), total bilirubin, and direct bilirubin) was obtained in exposed workers of both genders compared with controls (p < 0.001). Calculated liver damage risk scores were significantly higher in both females and males compared with controls (p < 0.001). The multivariate logistic regression analysis showed that direct bilirubin was the most important predictor of organic solvent mixture exposure in the studied group of workers. These results suggest that combined exposure to organic solvents even at low concentrations may lead to hepatotoxicity.

Health risk assessment of volatile organic compounds exposure near Daegu dyeing industrial complex in South Korea

BACKGROUND

Studying human health in areas with industrial contamination is a serious and complex issue. In recent years, attention has increasingly focused on the health implications of large industrial complexes. A variety of potential toxic chemicals have been produced during manufacturing processes and activities in industrial complexes in South Korea. A large number of dyeing industries gathered together in Daegu dyeing industrial complex. The residents near the industrial complex could be often exposed to volatile organic compounds. This study aimed to evaluate VOCs levels in the ambient air of DDIC, to assess the impact on human health risks, and to find more convincing evidences to prove these VOCs emitted from DDIC.

METHODS

According to deterministic risk assessment, inhalation was the most important route. Residential indoor, outdoor and personal exposure air VOCs were measured by passive samplers in exposed area and controlled area in different seasons. Satisfaction with ambient environments and self-reported diseases were also obtained by questionnaire survey. The VOCs concentrations in exposed area and controlled area was compared by t-test. The relationships among every VOC were tested by correlation. The values of hazard quotient (HQ) and life cancer risk were estimated.

RESULTS

The concentrations of measured VOCs were presented, moreover, the variety of concentrations according the distances from the residential settings to the industrial complex site in exposed area. The residential indoor, outdoor, and personal exposure concentrations of toluene, DMF and chloroform in exposed area were significantly higher than the corresponding concentrations in controlled area both in summer and autumn. Toluene, DMF, chloroform and MEK had significantly positive correlations with each other in indoor and outdoor, and even in personal exposure. The HQ for DMF exceeded 1, and the life cancer risk of chloroform was greater than 10^- 4 in exposed area. The prevalence of respiratory diseases, anaphylactic diseases and cardiovascular diseases in exposed area were significantly higher than in controlled area.

CONCLUSIONS

This study showed that adverse cancer and non-cancer health effects may occur by VOCs emitted from DDIC, and some risk managements are needed. Moreover, this study provides a convenient preliminarily method for pollutants source characteristics.

Effects of permissible maximum-contamination levels of VOC mixture in water on total DNA, antioxidant gene expression, and sequences of ribosomal DNA of Drosophila melanogaster

In this study, we aimed to investigate the mutagenic and carcinogenic potential of a volatile organic compound (VOC) mixture with references to the response of D.melanogaster using selected antioxidant gene expressions, RAPD assay and base-pair change of ribosomal 18S, and the internal transcribed spacer, ITS2 rDNA gene sequences. For this purpose, Drosophila melanogaster Oregon R, reared under controlled conditions on artificial diets, were treated with the mixture of thirteen VOCs, which are commonly found in water in concentrations of 10, 20, 50, and 75 ppb for 1 and 5 days. In the random amplified polymorphic DNA (RAPD) assay, band changes were clearly detected, especially at the 50 and 75 ppb exposure levels, for both treatment periods, and the band profiles exhibited clear differences between the treated and untreated flies with changes in band intensity and the loss/appearance of bands. Quantitative real-time PCR (qRT-PCR) analysis of Mn-superoxide dismutase (Mn-SOD), catalase (CAT) and glutathione-synthetase (GS) expressions demonstrated that these markers responded significantly to VOC-induced oxidative stress. Whilst CAT gene expressions increased linearly with increasing concentrations of VOCs and treatment times, the 50- and 75-ppb treatments caused decreases in GS expressions compared to the control at 5 days. Treatment with VOCs at both exposure times, especially in high doses, caused gene mutation of the 18S and the ITS2 ribosomal DNA. According to this research, we thought that the permissible maximum-contamination level of VOCs can cause genotoxic effect especially when mixed.

Neuropsychological Symptoms among Workers Exposed to Toluene and Xylene in Two Paint Manufacturing Factories in Eastern Thailand

The study analyzed the exposure factors that may lead to neuropsychological symptoms among 92 workers who were exposed to xylene and toluene and 100 workers who were not exposed to the solvents. The airborne concentration of xylene and toluene was evaluated with personal passive badges. The levels of methyl hippuric acid and hippuric acid in urine were assessed, and interviews were performed to observe the neuropsychological symptoms that may result from exposure to the solvents. The result showed that the average concentration for the exposed group of xylene in the paint company working environment was 2.7 (SD = 2.4) ppm and the average concentration of toluene was 9.5 (SD = 10.4) ppm. The average level of methyl hippuric acid in urine was 78 (SD = 74.7) mg/g creatinine. Factors that affected the neuropsychological symptoms included the following. (1) The impact of age: the risk (adjusted odds ratio) for getting psychosomatic symptoms in persons over 40 and exposed to xylene was 9.5 and the aOR of those exposed to toluene was 8.3. (2) The impact of not providing personal protective equipment was found to be sleep disturbance; it was found that the aOR of those exposed to xylene was 3.9, and the aOR of those exposed to toluene was 4.4. In summary, periodic examination of workers by occupational physician is needed for detection of early neuropsychological effects, especially psychosomatic symptoms, and sleep disturbances.

A study on neurobehavioral performance of workers occupationally exposed to solvent in synthetic resin manufacturing

Background:

One major effect of occupational solvent exposure is central nervous system (CNS) impairment, ranging from depression to encephalopathy with cognitive, behavioral changes. Exposures in industries being varied, classification of health outcomes for different exposures is important.

Objectives:

This study assessed neurobehavioral performance of synthetic resin manufacturing workers exposed to organic solvent, mainly formalin.

Materials and Methods:

This cross-sectional study selected subjects by random selection from all such workers of an Indian city. Questionnaire survey and assessment by a neurobehavioral test battery (NBT) was undertaken.

Results:

Comparison between actual and allied workers observed significant difference in tweezer dexterity, card sorting and backward memory scores. Significant effect of exposure was observed on tweezer dexterity, card sorting, and hand dynamometer scores.

Conclusion:

Changes of neurobehavioral performance might occur following solvent exposure and these changes might have a relationship with the quantum of exposure. Periodic examination of workers with NBT is needed for detection of early neurotoxic effects.

Effects of co-exposure of benzene, toluene and xylene to Drosophila melanogaster: alteration in hsp70, hsp60, hsp83, hsp26, ROS generation and oxidative stress markers

Benzene, toluene and xylene are monocyclic aromatic hydrocarbon compounds, used both as individual compound and as mixtures, in industry as well as household. Previous studies involving exposures to these compounds, individually, have shown that benzene was more toxic compared to toluene or xylene. Here, we tested a working hypothesis that toluene and/or xylene in a mixture containing benzene affect benzene induced toxicity in a non-target organism, Drosophila melanogaster. We exposed D. melanogaster larvae transgenic for hsp70, hsp83 or hsp26 and wild type (Oregon R strain) larvae to 25.0-100.0mM benzene, 25.0-100.0mM toluene and 25.0-100mM xylene, individually or in mixtures. Subsequently, we examined the expression of stress genes (encoding heat shock proteins, hsps), generation of reactive oxygen species (ROS), induction of anti-oxidant stress markers and emergence of flies under treatment as well as control conditions. We observed that all these endpoints were significantly altered in all the treatment groups compared to their respective controls. However, the magnitude of toxicity of a benzene-toluene (BT) or benzene-xylene (BX) or benzene-toluene-xylene (BTX) mixture was significantly lower in the organism than that of individual chemical. Our results also show the modulation of toluene toxicity by xylene. Present study suggests antagonistic effect of xylene and toluene on benzene toxicity and additive/synergistic effect of xylene on toluene induced toxicity. Thus, expression of stress genes may be used as an assay for detection of early cellular toxicity. Further, our study supports the use of Drosophila as an alternative animal model for first tier screening of adverse effects of chemical mixtures.

Occupational exposure to mixtures of organic solvents increases the risk of neurological symptoms among printing workers in Hong Kong

LEARNING OBJECTIVES

Summarize the nature and extent of exposure to organic solvents to which printing workers in this study were subjected. Compare the numbers of neurological symptoms in exposed and non-exposed workers and how they related to level of exposure, as defined by specific job title or by air sampling. Clarify the relationship between exposure to organic solvents and individual psychoneurological and other symptoms.

ABSTRACT

The health effects of low-dose occupational exposure to organic solvents remains unclear. A cross-sectional survey was conducted among 762 male printing workers to assess the impacts of exposure to mixtures of n-hexane, toluene, isopropyl alcohol, and benzene on neurological and other symptoms. After controlling for age, smoking, alcohol drinking, past exposure history, working hours and shift work, current exposure to solvent mixtures was significantly associated with the total number of neurological symptoms and with the prevalence of specific symptoms of the nervous system and mucous membrane irritation. The adjusted odds ratio of neurovegetative lability (1.7-5.9), abnormal or reduced smell (1.6-4.1), memory loss (1.8), and mucous membrane irritation symptoms (1.5-4.6) significantly increased in the exposed group, especially when the summation index of exposure exceeded one.

Neurobehavioral disturbances arising from occupational toluene exposure

BACKGROUND

Neurotoxicity of long-term exposure to toluene is known at higher levels than 50 ppm and is suspected at lower levels.

METHODS

A cross-sectional study carried out in two printing plants on 129 blue collar workers explored such a low level exposure of toluene. With 231 samples of ambient air, toluene concentration was estimated from 0 to 18 ppm in Plant A (offset) and from 2 to 27 ppm in Plant B (heliogravure). Outside any period of acute exposure, the workers answered a self-administered questionnaire on neurotoxic symptoms, EUROQUEST, and performed six psychometric tests on a computer-assisted version of battery NES.

RESULTS

After adjustment for confounders, we found significant relationships only between present exposure and Digit Span Forwards (DSF) performance (decrement is 1 digit for 40 ppm, P=0.04) and Digit Span Backwards (DSB) performance (decrement is 1 digit for 25 ppm, P=0.01). Neurotoxic symptoms were not significantly correlated with current exposure. No association was found between estimated cumulative exposure and either psychometric performances or neurotoxic symptoms.

CONCLUSION

In this study, low present exposure levels to toluene were associated with decrements of memory test performances.

Subtle increase in leukocyte counts in association with drinking and smoking habits

Peripheral leukocyte counts were examined in venous blood of more than 800 male workers exposed to toluene, xylenes, a combination of the two, or neither. Information on the social habits of smoking and drinking was obtained in an occupational health interview. The analysis showed that smoking (15 cigarettes/day on average) induced a significant increase (by 7%) in leukocyte counts, and that an additional increase was induced when the drinking habit was coupled with smoking. Drinking alone tended to increase the leukocyte counts but the effect was statistically nonsignificant, possibly because the number of nondrinking smokers was limited. The study stresses the importance of paying attention to smoking and drinking habits when evaluating hematological parameters such as peripheral leukocyte counts in solvent-exposed workers.

Urinary Phenylglyoxylic Acid Excretion after Exposure to Ethylbenzene among Solvent-exposed Chinese Workers

Factory surveys were conducted in the second half of work weeks on 360 solvent workers (202 men and 158 women) and 281 controls in China. Monitoring personal exposures showed that ethylbenzene exposure was low (geometric mean 1.8 ppm) and was accompanied by coexposure to toluene (1.5 ppm) and three xylene isomers (6.7 ppm). Urine samples collected at the end of the eight-hour shift were analyzed for phenylglyoxylic and mandelic acids by high-pressure liquid chromatography at 257 nm. Despite the low level of the exposures, a significant correlation was observed between ethylbenzene exposure and urinary phenylglyoxylic acid, with high (0.6-0.7) correlation coefficients, suggesting that urinary phenylglyoxylic acid is a good marker of occupational exposure to ethylbenzene. Mandelic acid also correlated with ethylbenzene exposure, but with much smaller coefficients (0.2), possibly because the method employed was more sensitive to phenylglyoxylic acid than to mandelic acid.

What's new in managing health hazards in pathology departments

Health hazards related to activities performed in pathology departments have represented, in recent years, an increasing concern among pathologists and pathology technicians. The major occupational health problems encountered in pathology departments are reviewed. They include biological hazards (tuberculosis, hepatitis, HIV, other infectious diseases), chemical hazards (formaldehyde, xylene(s), aromatic amines, methacrylates, glutaraldehyde, latex) and physical hazards (cut injuries, accidental fires, radiation). Current data suggest that infections (particularly, tuberculosis and hepatitis) still represent the more relevant risk. Exposure to HIV and Creutzfeldt-Jakob agent may be highly harmful but containment measures have been proven to be effective. The actual adverse effects due to chemicals seem to be less alarming than was previously believed. Attaining a safe work environment is an inherent element of good quality assurance management. This task is largely a matter of information, education, organization and common sense. Well-designed premises, efficient equipment and well-trained personnel are the keys to preventing and minimizing hazardous exposures. In order to provide current information that may be used by pathology staff to implement the functional quality of the workplace, organizational and preventive measures are described.