Correlation between urinary 2-methoxy acetic acid and exposure of 2-methoxy ethanol

Oxidative stress-mediated induction of pulmonary oncogenes, inflammatory, and apoptotic markers following time-course exposure to ethylene glycol monomethyl ether in rats

Ethylene glycol monomethyl ether (EGME) has been used in many products usually handled by humans including inks, paints, polishes, brake fluids and so on. This present study therefore, investigated its effect on lung, in a time-course study in male Wistar rats. Animals were orally administered 50 mg/kg body weight of EGME for a period of 7, 14, and 21 days. Following 7 days of oral exposure to EGME, activities of GPx and SOD were significantly increased, as well as levels of K-Ras, c-Myc, p53, caspase-3, TNF-α and, IL-6, while NO level and GST activity were significantly reduced compared with control. At the end of 14 days exposure, GSH level was significantly decreased, while levels of K-Ras, c-Myc, p53, caspase-3, TNF-α, IL-6, NO and the activities of SOD and GPx were significantly elevated with respect to control. After 21 days of EGME administration, levels of Bcl-2, IL-10, GSH and NO as well as GST activity were significantly decreased, while levels of K-Ras, c-Myc, p53, Bax, caspase-3, IL-6, IL-1β, TNF-α, as well as GPx, CAT, and SOD activities were significantly elevated compared with control. Lung histopathology revealed chronic disseminated alveolar inflammation, bronchiolitis, severe alveolar and bronchi hyperplasia, severe disseminated inflammation, thrombosis, and thickened vessels as a result of EGME exposures. Exposures to EGME could trigger lung damage via the disorganization of the antioxidant system, eliciting the up-regulation of inflammatory, apoptotic, and oncogenic markers in rats.

Suitability of the Limit Dose in Evaluating Reproductive Toxicity of Substances and Preparations

An oral dose of 1000 mg/kg body weight/day is mentioned in Organisation for Economic Cooperation and Development (OECD) and European Union (EU) guidelines as a default maximum dose in limit tests for studies on reproductive toxicity. This paper investigated whether upper range human exposure data from the workplace are supportive of this limit dose as an upper limit of possible human exposure. To this end, published exposure data as well as data from the database MEGA of the German “Berufsgenossenschaften” were evaluated. These data indicate that exposure concentrations in the range of 500 to 2000 mg/m3 (time-weighted averages) can be considered high human exposures to volatile compounds. Inhalation exposure to aerosols and dermal exposure result in lower dose levels. By applying suitable extrapolation factors, it was concluded that occupational exposures up to 325 mg/m3 can reliably be assessed with limit tests using a dose level of 1000 mg/kg/day. The limit dose has been proposed for use in the EU as a starting point to derive specific concentration limits for hazard classification of preparations containing reproductive toxicants, with the objective to consider the potency of the substances. This analysis shows that for some groups of chemicals, instead of the limit dose, the putative maximum levels of human exposure should be taken into account when deriving concentration limits for the classification of preparations. Furthermore, possible deviations from a linear correlation between concentration in the preparation and exposure should be considered.

Exposure of German residents to ethylene and propylene glycol ethers in general and after cleaning scenarios

Glycol ethers are a class of semi-volatile substances used as solvents in a variety of consumer products like cleaning agents, paints, cosmetics as well as chemical intermediates. We determined 11 metabolites of ethylene and propylene glycol ethers in 44 urine samples of German residents (background level study) and in urine samples of individuals after exposure to glycol ethers during cleaning activities (exposure study). In the study on the background exposure, methoxyacetic acid and phenoxyacetic acid (PhAA) could be detected in each urine sample with median (95th percentile) values of 0.11 mgL(-1) (0.30 mgL(-1)) and 0.80 mgL(-1) (23.6 mgL(-1)), respectively. The other metabolites were found in a limited number of samples or in none. In the exposure study, 5-8 rooms were cleaned with a cleaner containing ethylene glycol monobutyl ether (EGBE), propylene glycol monobutyl ether (PGBE), or ethylene glycol monopropyl ether (EGPE). During cleaning the mean levels in the indoor air were 7.5 mgm(-3) (EGBE), 3.0 mgm(-3) (PGBE), and 3.3 mgm(-3) (EGPE), respectively. The related metabolite levels analysed in the urine of the residents of the rooms at the day of cleaning were 2.4 mgL(-1) for butoxyacetic acid, 0.06 mgL(-1) for 2-butoxypropionic acid, and 2.3 mgL(-1) for n-propoxyacetic acid. Overall, our study indicates that the exposure of the population to glycol ethers is generally low, with the exception of PhAA. Moreover, the results of the cleaning scenarios demonstrate that the use of indoor cleaning agents containing glycol ethers can lead to a detectable internal exposure of residents.

Hematological Follow‐up of an Intervention Program Adding Rubber Glove‐Wearing to Local Ventilation for 2‐Ethoxyethanol Acetate‐Exposed Workers

The objective of this study was to evaluate an intervention program, implemented in year 1999, of wearing rubber gloves in addition to engineering control, and to follow-up the hematological effects of 2-ethoxyethanol acetate (2-EEA) exposure among workers in a silk-screening factory. All workers from the printing department with direct exposure to 2-EEA were recruited as the exposed group. Workers from the other departments were recruited as the comparison group. Hematological parameters were measured during health surveys conducted 3 times every two years. Information on personal characteristics and working habits was obtained through a structured questionnaire. More female workers were involved in manual printing resulting in higher exposure to 2-EEA. Hemoglobin and haematocrit levels in female exposed workers were significantly lower than those of female comparison workers in the 1st (1998) health survey, but not in the 2nd (2000) and 3rd (2002) health surveys. No difference was found between male exposed and comparison workers for all three surveys. Longitudinal analysis after adjusting for confounders using the general estimating equation model showed the hemoglobin, haematocrit, and RBC count were significantly higher for 2-EEA exposed workers than comparison workers across the 3 surveys (n=42). The results show that wearing rubber gloves in addition to local ventilation was effective at preventing direct dermal exposure to 2-EEA and ameliorated the hematological effects of 2-EEA exposure.

Correlation between urinary methoxyacetic acid and exposure of ethylene glycol dimethyl ether in a lithium battery plant

OBJECTIVE

To examine the correlation between airborne ethylene glycol dimethyl ether (EGdiME) exposures and the urinary methoxyacetic acid (MAA) and to approach the issue of a permissible exposure limit for EGdiME.

METHODS

The survey was conducted on Thursday. Workers occupationally exposed to EGdiME, as well as nonexposed controls, were studied in combination with one of the authors, who was coincidentally exposed to EGdiME while carrying out the study. Air levels of EGdiME were determined by personal sampling on passive gas tubes. Urine was collected from nine control subjects and ten workers immediately before and after the shift, and from one of the authors at intervals during 12 h. The analyses of EGdiME in air and MAA in urine were performed by gas chromatography with flame ionization detection.

RESULTS

The time-weighted average (TWA) air levels of EGdiME ranged from 0.7 to 10.5 ppm during 8 h work shifts. The urinary levels of MAA in one of the authors increased continuously during exposure and after the end of exposure. The levels of urinary MAA in the exposed workers were significantly higher than those in the control subjects. On the other hand, the postshift values were higher than the preshift values in the exposed workers, but the difference was not significant. A linear correlation was found between the TWA air levels of EGdiME and creatinine-adjusted MAA levels in urine collected at the end of the shift (r = 0.933; P < 0.0001). According to our equation, a linear extrapolation to the biological limit value recommended by Shih et al. (1999) of 40 mg MAA/g crea indicated an average inhalation exposure to EGdiME over the workweek of 12 ppm.

CONCLUSIONS

These results indicate that the determination of MAA in urine is suitable for use in the biological monitoring of EGdiME exposure.

The development and regulation of occupational exposure limits in Taiwan

The occupational exposure limits (OELs) in Taiwan was promulgated in 1974 and has been revised five times since then. Many of the OELs were adopted from the most recent ACGIH TLVs and US OSHA PELs. A total of 483 chemicals were listed in the current Taiwan OELs Standard. The procedures of OELs development in Taiwan include the IOSH organized a recommended exposure limits (RELs) Committee to select the target chemicals and to recommend the RELs through literature review based on the health effects in the first stage, then, the CLA put policy needs, economical and technical feasibility into consideration and set up the final OELs at the second stage. A standard operation manual of RELs Committee has been developed. Based on our experience, several issues including the participation of representatives from a comprehensive spectrum, communication/education and training/enforcement, continuous collection of the local exposure data and health hazard information, use of health risk assessment, consideration of economic, and technical feasibility, as well as the globalization and information and experience sharing are critical in developing the appropriate OELs. Three examples including benzene, crystalline silica, and 2-methoxy ethanol are given to demonstrate the operation of system.

Printed circuit board industry

The printed circuit board is the platform upon which microelectronic components such as semiconductor chips and capacitors are mounted. It provides the electrical interconnections between components and is found in virtually all electronics products. Once considered low technology, the printed circuit board is evolving into a high-technology product. Printed circuit board manufacturing is highly complicated, requiring large equipment investments and over 50 process steps. Many of the high-speed, miniaturized printed circuit boards are now manufactured in cleanrooms with the same health and safety problems posed by other microelectronics manufacturing. Asia produces three-fourths of the world's printed circuit boards. In Asian countries, glycol ethers are the major solvents used in the printed circuit board industry. Large quantities of hazardous chemicals such as formaldehyde, dimethylformamide, and lead are used by the printed circuit board industry. For decades, chemically intensive and often sloppy manufacturing processes exposed tens of thousands of workers to a large number of chemicals that are now known to be reproductive toxicants and carcinogens. The printed circuit board industry has exposed workers to high doses of toxic metals, solvents, acids, and photolithographic chemicals. Only recently has there been any serious effort to diminish the quantity of lead distributed worldwide by the printed circuit board industry. Billions of electronics products have been discarded in every region of the world. This paper summarizes recent regulatory and enforcement efforts.

Urinary methoxyacetic acid as an indicator of occupational exposure to ethylene glycol dimethyl ether

OBJECTIVE

To investigate whether methoxyacetic acid (MAA) is the metabolite of ethylene glycol dimethyl ether (EGdiME) in humans and whether its metabolite in urine can be used as a biomarker for exposure to EGdiME.

METHODS

Workers occupationally exposed to EGdiME, as well as nonexposed controls, were studied. Urine samples were collected from 20 control subjects and, on Friday postshift, from 14 workers. The identification and quantification of the metabolite were performed by gas chromatography/mass spectrometry (GC/MS) and GC/FID, respectively. Air samples were collected on activated charcoal tubes by area sampling with battery-operated pumps. The glycol ether was analyzed by GC/FID.

RESULTS

GC/MS clearly showed the metabolite of EGdiME to be MAA. Urinary MAA levels in the control subjects (background levels) were 0.0-0.3 mg/g crea. The levels of urinary MAA in the solvent-exposed workers were significantly (P<0.0001) higher than those in the control subjects. In the eight workers exposed to an average of 0.3 ppm of EGdiME and the six workers exposed to an average of 2.9 ppm, the mean urinary MAA level was 1.08 (range 0.6-1.5) mg/g crea and 9.33 (range 5.7-18.1) mg/g crea, respectively. These results can be explained by differences in the exposure intensity.

CONCLUSIONS

Our results suggest that MAA is the metabolite of EGdiME, and that MAA in urine may be used for biological monitoring of EGdiME exposures.

Evaluation of the protective effectiveness of gloves from occupational exposure to 2-methoxyethanol using the biomarkers of 2-methoxyacetic acid levels in the urine and plasma

AIMS

To evaluate the protective effectiveness of gloves from occupational exposure to 2-methoxyethanol (2-ME); and to examine the association of 2-methoxyacetic acid (MAA) in urine and plasma collected simultaneously from low 2-ME exposure and high 2-ME exposure workers in a semiconductor copper laminate circuit board manufacturing plant.

METHODS

Eight hour time weighted breathing zone monitoring was performed to verify the 2-ME exposure classification between workers in regular and special operations. Urine and plasma samples were simultaneously collected from 74 exposed and 80 non-exposed workers. MAA concentrations in the urine (UMAA) and plasma (PMAA) were measured using previously published methods. Three types of gloves worn by workers (cotton, rubber, and no gloves) were recorded by direct observations in the workplace and validated by person-to-person interview. Protective effectiveness indices (PEI) were used to evaluate the glove effectiveness.

RESULTS

There was no detectable 2-ME/MAA in the air, or in urine and plasma samples in non-exposed workers. The average UMAA and PMAA in special operations were 72.63 mg/g Cr. and 29.72 mg/l, significantly higher than values in regular operations (5.44 mg/g Cr. and 2.58 mg/l, respectively). PMAA showed satisfactory correlation to UMAA in all participants from both regular and special operations. The rubber gloves provided significant reduction in 2-ME uptake, whereas cotton gloves provided little protection with fluctuating effectiveness, based on PEI estimates.

CONCLUSIONS

PMAA, similar to UMAA, could serve as a specific biomarker for 2-ME exposure. Wearing impermeable rubber gloves during high risk tasks can reduce major 2-ME exposure. Other improvements, including engineering control, should be provided to diminish worker exposure to 2-ME in occupational environments.

Hepatic Effects in Workers Exposed to 2-Methoxy Ethanol

The objective of this study was to investigate the effects of 2-ME on hepatic function in exposed workers. Fifty-three impregnation workers from two copper-clad laminate-manufacturing factories using 2-ME as a solvent were recruited as the exposed group. Another group of 121 lamination workers with indirect exposure to 2-ME was recruited as the comparison group. Environmental monitoring of air 2-ME concentrations and biological monitoring of urine 2-methoxy acetic acid concentrations were performed. Venous blood was collected for blood biochemistry analyses. Liver function examination results showed that the aspartate amino transferase, alanine amino transferase, and gamma-glutamyl transferase in the 2-ME-exposed workers were not significantly different from those in the comparison workers. After adjustment for hepatitis carrier status, gender, body mass index, and duration of employment, no difference were found between exposed and comparison groups. We conclude that 2-ME was not a hepatotoxin.

Haematological effects among silk screening workers exposed to 2-ethoxy ethyl acetate

BACKGROUND

2-Ethoxy ethyl acetate (2-EEA) is a solvent with broad industrial and commercial applications. It has been reported to cause hematological toxicity, infertility, and teratogenesis.

AIMS

To investigate the haematological effects in 2-EEA exposed workers.

METHODS

Workers from one silk screening shop (n = 29), using 2-EEA as the major cleaning and printing solvent, were recruited as a high exposure group. Workers with indirect and non-exposure to 2-EEA (n = 56) were recruited as the comparison group. Venous blood was collected for blood routine examination. Air concentration of 2-EEA in this plant was measured by eight hour personal sampling.

RESULTS

The geometric mean (GM) of air concentration of 2-EEA in the high exposure group was 7.41 ppm (range 1.35-16.5 pppm). The mean exposure of female workers (GM = 9.34 ppm) was significantly higher than that of male workers (GM = 4.87 ppm). The GM of air 2-EEA concentration in the comparison group was 0.07 ppm (range: non-detectable to 3.62 ppm, n = 26). The haemoglobin and haematocrit in the female high 2-EEA exposure workers were significantly lower than those of female workers in the comparison group. No difference was found between male 2-EEA high exposure and comparison group workers. The haemoglobin, haematocrit, and RBC count in the study population had a significant dose-response relation with air 2-EEA levels.

CONCLUSION

Results suggest that 2-EEA is a haematological toxicant, which leads to anaemic status in high exposure female workers.

Sensitive determination of alkoxyethanols by pre-column derivatization with 1-anthroylnitrile and reversed-phase high-performance liquid chromatography

A new method for simultaneous determination of alkoxyethanols (2-methoxyethanol, 2-ethoxyethanol, 2-isopropoxyethanol, and 2-butoxyethanol) by high-performance liquid chromatography (HPLC) with fluorescence detection has been developed. The alkoxyethanols and an internal standard (2-phenoxyethanol) were derivatized by treatment with 1-anthroylnitrile to give the anthroyl esters. The esterification was completed in 30 min in the presence of quinuclidine as base catalyst at room temperature. After stopping the reaction, an aliquot of the final solution was injected into the HPLC. The resulting anthroyl esters of the alkoxyethanols and the internal standard were separated on a C18 reversed-phase column with acetonitrile-water-acetic acid (65:35:0.1, v/v) as the mobile phase and detected fluorimetrically at excitation and emission wavelengths of 360 nm and 460 nm, respectively. The detection limits of the derivatives as alkoxyethanols at a signal-to-noise ratio of 3 were in the range of 1-3 pg per injection. The minimal amounts of alkoxyethanols derivatized in the reaction mixture for derivatization to determine the limits of detection were approximately 0.5 ng. This HPLC method was applied to the determination of some of alkoxyethanols in the air of the workplace where the thinner containing alkoxyethanols was used for painting.

Follow up study of haematological effects in workers exposed to 2-methoxyethanol

AIMS

To examine the association between 2-methoxyethanol (2-ME) exposure and haematological effects, as well as the recovery from these haematological effects with continuous reduction in exposure to 2-ME.

METHODS

Twenty nine exposed and 90 non-exposed workers were recruited. Haematological parameters, eight hour full shift personal exposure to 2-ME, and urinary 2-methoxyacetic acid (MAA) were repeatedly measured in three consecutive surveys within six months.

RESULTS

Results of haematological examination in the first exposure survey showed that haemoglobin, packed cell volume, and red blood cell count in the male exposed workers were significantly lower than those in the comparison workers. The frequency of anaemia in the exposed group (42%) was significantly higher than that in the comparison group (3%). The haematological effects were significantly associated with the urinary MAA of exposed workers. The haematological effects had returned to normal in the first follow up survey 2.5 months later, when a reduction in 2-ME exposure was noted. Haematological results of the second follow up examination six months later remained normal. The mean airborne exposure of 2-ME in the three surveys dropped from 35.7 to 2.65, then to 0.55 ppm. The mean urinary MAA of exposed workers in the three surveys was reduced from 57.7 to 24.6, then to 13.5 mg/g creatinine (n = 29). The reduction in exposure through both inhalation and potential dermal contact with 2-ME might account for the haematological recovery.

CONCLUSION

2-ME is a haematological toxin which leads to anaemia in exposed workers. However, the toxic haematological effects of 2-ME persist for only a short period of time after cessation or reduction of exposure.

Measurement of percutaneous uptake of 2-methoxy ethanol vapor in humans

Absorption of vapors through skin has been largely ignored in occupational health, although for ethylene glycol ethers this route of exposure could be more important than inhalation. We used an automated concentration and humidity controlled system to measure real-time percutaneous absorption of 2-methoxy ethanol (ME) vapor in seven volunteers. The exposure concentration (300 +/- 10 ppm or 25 +/- 0.5 ppm), humidity (80 +/- 2%), and temperature (27.5 +/- 0.5 degrees C) were controlled throughout the experiments. Uptakes during 4-hour single-arm exposure at 25 ppm and 300 ppm were 7.0 mg and 65.3 +/- 25.0 mg, respectively, with corresponding uptake rates of 1.36 micrograms/cm2/hr and 13.2 +/- 5.0 micrograms/cm2/hr. Percutaneous absorption was consistent and unsaturated during exposure. Because the permeability constant of ME vapor (14.0 +/- 5.3 cm/hr) was much higher than that of many widely used organic chemicals, we concluded that vapor absorption through skin is a significant contributor to overall ME exposure.