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.

Urinary elimination of nickel and cobalt in relation to airborne nickel and cobalt exposures in a battery plant.

OBJECTIVE: To estimate the relationship between Ni concentrations in the ambient air and in the urine, at a battery plant using nickel hydroxide. METHODS: Workers occupationally exposed to a mixture of nickel hydroxide, metallic cobalt and cobalt oxyhydroxide dust were studied during two consecutive workdays. Air levels of Ni and Co in total dust were determined by personal sampling in the breathing zone. Both metals in air were sampled by Teflon binder filters and analyzed by inductively coupled plasma absorption emission spectrophotometry. Urine was collected from 16 workers immediately before and after the work shift. Urinary Ni and Co concentrations were measured by electrothermal atomic absorption spectrometry. RESULTS: A poor correlation was seen between Co in the air and in post-shift urine (r = 0.491; P < 0.01), and no correlation was found between Ni in the air and in post-shift urine (r = 0.272; P = 0.15), probably due to the use of respiratory protection. The subjects were exposed to higher levels of Ni than Co (Ni (mg/m(3)) = -0.02 + 7.41 Co (mg/m(3)), r = 0.979, P < 0.0001). Thus, exposure to Co at 0.1 mg/m(3) should produce a Ni level of 0.7 mg/m(3). According to section XIII of the German list of MAK and BAT Values, a relationship between exposure to Co and urinary Co excretion, Co (microg/l) = 600 Co (mg/m(3)), has been established and the relationship between soluble or insoluble Ni salts in the air and Ni in urine was as follows: Ni (microg/l) = 10 + 600 Ni (mg/m(3)) or Ni (microg/l) = 7.5 + 75 Ni (mg/m(3)). Assuming nickel hydroxide to be soluble and to be insoluble, the Ni concentrations corresponding to Ni exposure at 0.7 mg/m(3) were calculated as 430 and 60 microg Ni/l, respectively. Similarly, exposure to Co at 0.1 mg/m(3) should result in Co urinary concentrations of 60 microg Co/l. On the other hand, a good correlation was found between Co and Ni in post-shift urine (Ni (microg/l) = 9.9 + 0.343 Co (microg/l), r = 0.833, P < 0.0001). On the basis of this relationship, the corresponding value found in our study was 0.343 x 60 microg Co/l + 9.9 = 30.5 microg Ni/l. This value was close to that calculated by the equation for a group of insoluble compounds, but about 14 times lower than that calculated by the equation for a group of soluble compounds. CONCLUSIONS: Our results suggest that exposure to nickel hydroxide yields lower urine nickel concentrations than the very soluble nickel salts, and that the grouping of nickel hydroxide might be reevaluated. Therefore, to evaluate conclusively the relationship between nickel hydroxide dust in the air and Ni in post-shift urine, further studies are necessary.

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.

Methyltetrahydrophthalic acid in urine as an indicator of occupational exposure to methyltetrahydrophthalic anhydride.

OBJECTIVE: To investigate whether methyltetrahydrophthalic acid (MTHP acid) in urine can be used as a biomarker for exposure to methyltetrahydrophthalic anhydride (MTHPA). METHODS: Workers occupationally exposed to MTHPA were studied in combination with one of the authors, who was experimentally exposed to MTHPA. Air levels of MTHPA were determined by personal sampling in the breathing zone. The MTHPA in air was sampled by silica gel and analyzed by gas chromatography (GC) with electron-capture detection. Urinary levels of MTHP acid, a metabolite of MTHPA, were determined in 15 subjects in total. Urine was collected from 14 workers immediately before the start of the work shift and then after 4 and 8 h, and from one of the authors at intervals during 24 h. MTHP acid in urine was analyzed by GC with mass spectrometric detection. RESULTS: The time-weighted average (TWA) air levels ranged from 1.0 microg to 200 microg MTHPA/m3 during 8 h work shifts. The urinary levels of MTHP acid increased during exposure and decayed after the end of exposure, with an estimated half-time of about 3 h. A close correlation was found between the TWA air levels of MTHPA and creatinine-adjusted MTHP acid levels in urine collected at the end of the shift (r = 0.955; P < 0.0001). The current occupational exposure limit of 50 microg MTHPA/m3 (Japan Society for Occupational Health) corresponded to about 1300 microg MTHP acid/g creatinine, which was equivalent to about 900 nmol/mmol creatinine in the International System of Units (SI). CONCLUSIONS: These results indicate that the determination of MTHP acid in urine is suitable for use in the biological monitoring of MTHPA exposure.

Occupational dermatitis from soldering flux.

The aim of this study was to determine the specific agent responsible for eczema on the forearms of 2 electronic assemblers who cleaned out a flux-spraying unit once a week. Soldering flux can be a source of skin irritation as well as allergy. Patch test with dried flux residue (as is) and rosin in dilution series of 20%, 10%, and 1% in olive oil was performed. Readings were taken on day 2 and day 3. The rosin in dilution series was negative; however, the flux residue gave a + reaction on day 2, and by day 3 the reaction had weakened (+?). Similar results were obtained in 2 unexposed controls. Patch tests results in our cases indicate that the flux used in the soldering process caused irritant contact dermatitis.

[The working environment control of anhydride hardeners from an epoxy resin system].

Epoxy resins are widely used in adhesives, coatings, materials for molds and composites, and encapsulation. Acid anhydrides such as methyltetrahydrophthalic anhydride are being used as curing agents for epoxy resins. The anhydride hardeners are well-known industrial inhalant allergens, inducing predominantly type I allergies. In the electronic components industry, these substances have been consumed in large quantities. Therefore, safe use in the industry demands control of the levels of exposure causing allergic diseases in the workshop. We conducted a prospective survey of two electronics plants to clarify how to control the atmospheric level of the anhydrides in the work environment. Measurements of the levels of the anhydrides in air started according to the Working Environment Measurement Standards (Ministry of Labour Notification No. 46, 1976) in April 2000, along with improvements in the work environment. A value of 40 micrograms/m3 was adopted as the administrative control level to judge the propriety of the working environment control. A total of 2 unit work areas in both plants belonged to Control Class III. The exposure originated from manual loading, casting, uncured hot resins, and leaks in an impregnating-machine or curing ovens. In order to achieve the working environment control, complete enclosure of the source, installation of local exhaust ventilation, and improvement or maintenance of the local exhaust ventilation system were performed on the basis of the results of the working environment measurement, with the result that the work environment was improved (Control Class I). It became evident that these measures were effective just like other noxious substances.

Metalworking fluid hand dermatitis.

In a household appliance plant, several rinse-free lubricating fluids have been used instead of neat mineral oils since 1994: mixtures of isoparaffinic hydrocarbons with 9 to 14 carbons per molecule. As such they denature keratin, irritate and defat the skin, and remove water from it. Work gloves have been worn over plastic gloves and separate, reusable, cotton inner gloves have been added to absorb sweat since skin problems were first recognized in 1994. All 74 males (mean +/- SD, 38.8 +/- 8.0 years) who work with the fluids were interviewed and given cutaneous examinations when indicated. While 4 cases of severe dermatitis and 31 cases of mild dermatitis were identified, 28 individuals gave a history of similar problems since the use of lubricating fluids. Their symptoms were typical of primary skin irritation. The hands were the commonly affected region (63 of 63 cases: 100%), followed by the thighs (15.9%) and trunk (11.1%). The work-related skin symptoms identified were less common in workers who immediately removed the liquid with soap and water, when it is spilled on the hands, than in those who did not, but the difference was not statistically significant (7/23 (30.4%) vs. 28/51 (54.9%), p=0.051 by chi-square test). Since skin contact with metalworking fluids (MWF) is often unavoidable, good personal hygiene is important in minimizing potential adverse health effects. Health education thus remains the most important preventive measure against irritant contact dermatitis among workers handling MWFs.

A cross-sectional survey of 32 workers exposed to hexahydrophthalic and methylhexahydrophthalic anhydrides.

The relation between exposure and sensitization or the appearance of symptoms of the eyes and airways was investigated in a cross-sectional study on 32 workers from a plant using epoxy resin with a mixture of hexahydrophthalic anhydride (HHPA) and methylhexahydrophthalic anhydride (MHHPA) as a hardener. The main component in the hardener was HHPA, and the geometric mean concentrations of HHPA in the workplaces were extremely low (<40 microg/m3) in recent years, compared to the Occupational Exposure Limit-Ceiling for phthalic anhydride (2 mg/m3). However, specific IgE antibody to HHPA was detected in serum from 8 (25%) out of the workers: of those, 5 workers experienced symptoms of the eyes and nose during work (group sensitized symptomatic (SS)) and 3 workers did not (group sensitized nonsymptomatic (SN)). The other 24 workers had no signs of sensitization and did not complain of work-related symptoms. Based on occupational history and anamnestic data, it was concluded that one subject in the SS group and all the subjects in the SN group had been sensitized by higher exposures in the past. The symptoms of 4 subjects in the SS group occurred only when carrying out short-time, particular tasks (15-30 min) a few times a day, such as the resin mixing procedures, manual application of the resin, or opening of ovens. High peak exposures were estimated to have occurred during the particular tasks. Our results suggest that short-time peak exposures may have a great impact on the development of specific IgE or work-related symptoms. Therefore, to minimize the risk of sensitization and work-related symptoms, a reduction of exposure during particular tasks with high peak exposures, along with a decrease in mean 8-h time-weighted average exposure, should be achieved.

Occupational dermatitis from a one-component naphthalene type epoxy adhesive.

In an electronics plant, a new one-component naphthalene type epoxy resin was used as an adhesive for reinforcing a circuit board. The resinous part of the adhesive consisted of diglycidyl ether of bisphenol A (DGEBA) and 1,6-bis(2,3-epoxypropoxy)naphthalene type epoxy resins. The hardener was methylhexahydrophthalic anhydride (MHHPA). Of 54 workers, 15 (27.8%) were diagnosed to have work-related dermatitis but were not patch tested. Therefore, it was impossible to determine the specific agent responsible for the worker's symptoms or to distinguish between allergic and irritant contact dermatitis. They worked without protective gloves until they started to develop skin symptoms. The hands were the commonly affected region (13 out of 15 cases). The latent period of dermatitis was very short (mean 2.2 weeks). Of these, 10 cases (66.7%) received medication for dermatitis, and 9 cases (60%) were transferred to other work. The work-related skin symptoms were closely related to the specific tasks, i.e., filling dispensers with the adhesive and manual application of the adhesive to a portion of a circuit board using a dispenser. For occupational hygiene reasons, contact with epoxy resins should be minimized by taking all possible measures into use, including protective gloves. Further studies are required to clarify the allergenicity of 1,6-bis(2,3-epoxypropoxy)naphthalene, since very little is known about the mechanism through which it leads to the symptoms of dermatitis.