No acute effects of an exposure to 50 ppm methyl methacrylate on the upper airways.

PURPOSE: The German MAK value of methyl methacrylate has been fixed at 50 ppm. The aim of this study was to evaluate possible acute effects of an exposure to 50 ppm methyl methacrylate on the upper airways of human subjects. METHODS: Twenty healthy subjects were exposed to 50 ppm methyl methacrylate and to air (sham) in an exposure chamber for 4 h according to a crossover design. Symptoms were assessed by the SPES questionnaire. Olfactory thresholds for n-butanol and mucociliary transport time were measured before and after exposure. Concentrations of interleukin 1ß and interleukin 8 were determined in nasal secretions taken after exposure. mRNA levels of interleukins 1ß, 6 and 8, tumor necrosis factor α, granulocyte-macrophage colony-stimulating factor, monocyte chemotactic protein 1, and cyclooxygenases 1 and 2 were measured in nasal epithelial cells, obtained after exposure. Possible effects were investigated by semiparametric and parametric crossover analyses. RESULTS: The score of the item "irritation to the nose" was slightly elevated following exposure to methyl methacrylate (p ≤ 0.01). Olfactory functioning was not impaired. Mucociliary transport time did not change. Neither concentrations of interleukins in nasal secretions nor mRNA levels were elevated. CONCLUSION: Only minor irritating effects on the nose were observed. The acute exposure to 50 ppm methyl methacrylate did not cause any adverse effects. However, the results cannot be extrapolated to chronic exposure.

Acute effects of an exposure to 100 ppm 1-methoxypropanol-2 on the upper airways of human subjects.

The German MAK value of 1-methoxypropanol-2 has been fixed at 100 ppm. The aim of this study was to evaluate possible acute effects of an exposure to 100 ppm 1-methoxypropanol-2 on the upper airways of human subjects. Twenty subjects were exposed in a crossover design to 100 ppm 1-methoxypropanol-2 and to air in an exposure chamber for 4h. Subjective symptoms were assessed by questionnaire. Olfactory thresholds for n-butanol and mucociliary transport time were measured before and after exposure. Concentrations of interleukin 1ß and interleukin 8 were determined in nasal secretions taken after exposure. mRNA levels of interleukins 1ß, 6 and 8, tumor necrosis factor α, granulocyte-macrophage colony-stimulating factor, monocyte chemotactic protein 1, and cyclooxygenases 1 and 2 were measured in nasal epithelial cells, obtained after exposure. Possible effects were investigated by semiparametric and parametric cross-over analyses. Subjects did not have any subjective irritating symptoms. The olfactory threshold was slightly elevated following exposure to 1-methoxypropanol-2. Mucociliary transport time did not change. Neither concentrations of interleukins in nasal secretions nor mRNA levels except for interleukin 1ß were higher after exposure to 1-methoxypropanol-2. In conclusion, the acute exposure to 100 ppm 1-methoxypropanol-2 did not cause clear-cut adverse effects in test subjects.

Effects of an acute exposure to toluene on the DNA repair activity of the human 8-oxoguanine DNA glycosylase 1 (hOGG1) in healthy subjects.

The structure and previous studies on the biotransformation of toluene lead to the suspicion that metabolites may be formed which preferentially react with strongly nucleophilic partners such as sulfhydryl groups of cysteines in proteins. Human 8-oxoguanine DNA glycosylase 1 removes the major oxidative DNA damage and possesses eight cysteines. Its potential inactivation may lead to accumulation of DNA damage by reactive oxygen species formed by exogenous agents or by ubiquitous endogenous processes. The goal of the present investigation was to study the in vivo effect in humans of an acute toluene exposure on hOGG1 activity. Twenty healthy, non-smoking males were exposed to 50 ppm toluene and to filtered air in an exposure chamber for 270 min, using a cross-over design. Before and 30 min after the end of exposure, blood samples were taken and toluene concentrations and the hOGG1 activity were measured. hOGG1 activity was determined in peripheral mononuclear blood cells. Thirty minutes after exposure to toluene, we found a median blood concentration of 0.25 mg toluene/l. Compared with the activity before exposure, upon exposure to toluene a statistically insignificant median increase of hOGG1 activity by +0.4% and upon exposure to air by +2.3% was determined. Thus, no reduction of the hOGG1 repair activity after acute exposure to 50 ppm toluene was observed.

No acute effects of an exposure to 50 ppm acetaldehyde on the upper airways.

OBJECTIVE: German MAK value of acetaldehyde has been fixed at 50 ppm to prevent from irritating effects. The threshold value is mainly based on animal experiments. The aim of this study was to evaluate acute effects of an exposure to 50 ppm acetaldehyde on the upper airways of human subjects. METHODS: Twenty subjects were exposed to 50 ppm acetaldehyde and to air in an exposure chamber for 4 h according to a crossover design. Subjective symptoms were assessed by questionnaire. Olfactory threshold for n-butanol and mucociliary transport time were measured before and after exposure. Concentrations of interleukin 1beta and interleukin 8 were determined in nasal secretions taken after exposure. mRNA levels of interleukins 1beta, 6 and 8, tumour necrosis factor alpha, granulocyte-macrophage colony-stimulating factor, monocyte chemotactic protein 1, and cyclooxygenases 1 and 2 were measured in nasal epithelial cells, gained after exposure. Possible effects were investigated by semiparametric and parametric crossover analyses. RESULTS: Exposure to acetaldehyde did not cause any subjective irritating symptoms. Olfactory threshold did not change. Mucociliary transport time increased insignificantly after exposure to acetaldehyde. Neither concentrations of interleukins in nasal secretions nor mRNA levels of inflammatory factors were higher after exposure to acetaldehyde. CONCLUSION: An acute exposure to 50 ppm acetaldehyde did not cause any adverse effects in test subjects.

Acute effects of an organic solvent mixture on the human central nervous system.

OBJECTIVES: At workplaces, organic solvents are often used as mixtures. Nevertheless, there is limited knowledge of their acute effects on human central nervous system. Here we report the effects of a toluene-acetone mixture. METHODS: In a parallel design, subgroups of 12 healthy men each were exposed to a mixture containing 25 ppm acetone and 250 ppm toluene or to air (control) in an exposure chamber for 4.5 hours. Concentrations corresponded to the German TLV (TRGS 403). Concentrations of toluene and acetone in venous blood were measured by headspace gas chromatography. Subjects were sedentary. The following tests were performed before and at the end of exposure: Questionnaires, simple reaction time, vigilance, quantitative analysis of EEG with open and closed eyes and during the Color Word Stress test, and visual evoked potentials (VEP). RESULTS: Blood levels were 0.14 (+/- 0.04 SD) mg toluene/l and 5.43 (+/- 1.37 SD) mg acetone/l at the end of solvent exposure. Scores of neurotoxic and irritating symptoms were not elevated during solvent exposure. Exposed subjects performed as well as control subjects on the simple reaction time test and on the vigilance test, neither reaction time nor number of hits differed significantly. A general linear model on log transformed spectral power values showed insignificant changes in EEG. In the alpha subset2-band an average reduction to 86 % was observed in exposed as compared to non exposed subjects with closed eyes, a reduction to 88 % in the theta-band with open eyes, and a reduction to 92 % in the theta-band during the Color Word Stress test. VEP P 100 latencies and amplitudes did not change. CONCLUSION: The mixture consisting of toluene and acetone did not cause any adverse acute effect. With respect to EEG data, possible subclinical effects on central nervous system cannot be excluded.

Acute effects of 200 ppm 1,1,1-trichloroethane on the human EEG.

OBJECTIVES: Even low concentrations of organic solvents used at work may cause acute effects on the human central nervous system. We investigated the acute effects of 200 ppm 1,1,1-trichloroethane on the human EEG. METHODS: 12 healthy subjects were exposed for 4 hours to 200 ppm and to 20 ppm (control) in an exposure chamber in a cross-over design. EEG was recorded before (reference) and at the end of each exposure with eyes closed and open and during the Color Word Stress test. Spectral power was calculated by Fast Fourier transformation and related to reference values (per cent of baseline). Subjective symptoms and effects of blinding with 20 ppm 1, 1,1-trichloroethane were assessed by questionnaire. RESULTS: Blinding was not effective because of the strong smell of 1,1, 1-trichloroethane. The score for tiredness increased slightly during and after exposure to 200 ppm. In the closed eye condition, the median percentage of spectral power increased at all electrodes of the delta -band, significantly at temporo-occipital leads. In the theta-band, the percentage of the median spectral power was elevated at most of the electrodes but the parietal and some temporal ones. As to the alpha subset1-band, the percentage of the median spectral power was lower at the temporo-parieto-occipital electrodes, yielding significance at T subset4. In the alpha subset2-band, the percentage of the median spectral power was lower at all electrodes, significantly at T subset4 and T subset5. The percentage of the median spectral power of the temporo-parieto-occipital electrodes of the beta subset1 -band was lower during exposure to 200 ppm. There were no clear-cut changes in the beta subset2 -band, in the open eye condition and during the Color Word Stress test. CONCLUSION: The changes in EEG and the increased score for tiredness indicate a slight sedative effect of 200 ppm 1,1,1-trichloroethane.

Saliva as an alternate for blood to measure concentrations of acetone under exposure to isopropanol.

OBJECTIVES: In occupational medicine, blood concentrations are often measured to judge the internal burden of workers at work-place during exposure to a potentially hazardous substance. However, blood-withdrawals are invasive and can often not be taken at work-place due to hygienic reasons. Sampling of saliva is non-invasive and easy to perform even at workplace. In order to substitute blood analysis, analysis of saliva has to be as specific and sensitive as blood investigations. Therefore acetone-concentrations in blood and in saliva during exposure to isopropanol were compared. METHODS: 18 healthy non-smokers were exposed to 360 ppm isopropanol in an exposure chamber over 4 h. Once an hour during exposure and 30 min after, blood and saliva were sampled. Saliva was collected by a cotton plug over 10 minutes and stored in an airtight closed headspace tube. Concentrations of the metabolite acetone were measured by gas chromatography. - RESULTS: The concentrations of acetone in blood and saliva rose continually during exposure and dropped after exposure-cessation. High correlations between concentrations of acetone in blood and saliva were found for each individual and the entire group (entire group: r = 0.8568, p <0.0001, y = 0.8374x - 0.4404). CONCLUSIONS: Acetone-measurement in saliva is a non-invasive, easily conductable and reliable method for estimating the internal burden of isopropanol-exposure. Further studies for the standardization and validation are necessary to impose a threshold limit value on work-place isopropanol-exposure.

Acute changes in the EEG of workers exposed to mixtures of organic solvents.

In a pilot study, 11 workers were exposed to mixtures of organic solvents during the cleaning of printing rolls. The exposure was considered as low to moderate. The "electroencephalogram (EEG)" was recorded before and after the cleaning. The spectral power was calculated by Fast Fourier Transformation in six frequency bands. After exposure the spectral power in particular increased in the alpha-1 band and in the temporooccipital leads of the delta band in the closed-eye condition.

Effect of subacute occupational exposure to toluene on color vision.

The subacute effect of toluene on color vision was examined in 59 rotogravure workers exposed to toluene. Toluene and ethanol were determined in blood and color vision testing was performed on Monday before shift and on Friday after shift. The battery included the Ishihara plates, the Velhagen plates, the Standard Pseudoisochromatic Plates part 2, the Farnsworth panel D-15 test, and the Lanthony desaturated panel D-15 test. The concentrations of toluene in blood ranged from < 0.22 to 7.37 mg/l. No effect of toluene on color vision could be observed even in a subgroup of highly exposed workers. So their ability to judge colored products was not impaired.

Lead content of fetal tissues after maternal intoxication.

A female employee was exposed to lead dust for 8 h daily from 4. 5. 1982 to 20. 5. 1982. During this time conception occurred (1st day of last menses 4. 5. 82). Acute symptoms of lead intoxication were not observed in this subject but were in other employees. Measurements of lead content were started after the end of exposure and continued for 6 months until normal values were obtained. Because of the half-life of nearly 20 days for lead elimination from blood the estimated body burden at the end of exposure was about 1200 ppb. The fetal tissue samples contained between 0.4 (brain) and 7.9 (liver) micrograms lead/g dry weight. The fetal lead was mainly stored in bone, blood and liver. From the results given a delayed elimination of fetal lead is suggested.