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PubMedDate not supplied

Environmental exposure and occupational asthma.

Environmental exposure in relation to occupational asthma (OA) concerns the exposure of subjects in the work-place. There are qualitative and quantitative differences in occupational exposures which may influence the development and/or the course of OA. Although more than 300 different agents have been described causing OA, 5-6 groups of substances are sufficient to explain more than 80% of all cases of OA. In addition, a variant of occupational asthma without latency period may occur after an acute inhalation of massive concentrations of irritants, and exacerbations of a pre-existent asthma may be due to products or conditions in the work-place. Despite our increased knowledge of the etiology and pathophysiology of OA, its prevalence in the industrialised world has been relatively steady over the last decade. Therefore, the transfer of knowledge has not been sufficiently effective in the prevention of the disease. The results of studies on the exposure-response relationship for several high molecular weight chemicals (and fewer low molecular weight) indicate that sensitisation may be prevented in large part by reducing work-place concentrations of these agents. These data give support to the attempt to develop Threshold Limit Values (TLV) for sensitisers.

Asthma↗
PubMed2001

Acute effects on the human EEG after an external exposure to 200 ppm methanol.

OBJECTIVES: Even low concentrations of organic solvents may cause acute effects on the human central nervous system. The German MAK (threshold limit value) of methanol is 200 ppm. The aim of this study was to investigate whether acute exposure to 200 ppm methanol causes adverse effects, measured by EEG, and moreover, whether it is possible to differentiate between sedative and excitatory effects with this method. METHODS: Twelve healthy subjects were exposed for 4 h to 200 ppm and to 20 ppm (control) in an exposure chamber in a cross-over design. The EEG was recorded before (reference) and at the end of each exposure with, the subject's eyes closed and opened and during a choice reaction test (color word stress test). Spectral power was calculated by fast Fourier transformation. Subjective symptoms and effects of blinding with 20 ppm methanol were assessed by questionnaires. RESULTS: The study was a single-blind one. During subjects' exposure to 200 ppm, their scores for prenarcotic and irritating symptoms were not different from controls. In the closed-eye condition of subjects, the spectral power of the theta-band and of some electrodes of the delta-band was significantly less at the end of exposure to 200 ppm, than that of controls. In the open-eye condition and during the color word stress test no significant changes were found. CONCLUSION: The changes in the theta-band suggest a slight excitatory effect of 200 ppm methanol. The effect was weak, as scores of acute symptoms did not change. With respect to our results, it is not necessary for the MAK value to be decreased.

Adult↗
PubMed1998

[Quantification of inhaled exposure to alpha-amylase in 2 bakeries].

BACKGROUND: Baker's asthma and baker's rhinitis are among the most frequent occupational diseases. A major cause is the high exposure to flour dust in the workplace and to allergenic enzymes like alpha-amylase from Aspergillus oryzae (allergen name: Asp o 2). METHODS: To quantify allergen exposure in the workplace, 31 personal dust samples in a conventional small bakery (six workers) and in a biobakery (seven workers) were collected. Using a recently developed two-site enzyme-linked immunosorbent assay based on monoclonal antibodies to alpha-amylase from Aspergillus oryzae, the allergen content of these dust samples was determined. RESULTS: Dust exposure in the biobakery was in the range between 3.5 and 12 mg/m3 (median: 5.2 mg/m3) and in the conventional bakery between 0.9 and 118 mg/m3 (median 8.5 mg/m3). 23 out of 31 exposure measurements showed values higher than 4 mg/m3 (threshold limit value for inhalable dust). In the biobakery, no fungal alpha-amylase could be detected. 15 out of 17 samples taken in the conventional bakery contained fungal alpha-amylase in the range between 0.2 and 88 ng per mg dust. The geometric mean of alpha-amylase exposure in this bakery was 13 ng Asp o 2/m3, and the maximum exposure was 4.8 micrograms/m3. In four cases, fungal alpha-amylase was detected although exposure to dust was below the threshold limit of 4 mg/m3. CONCLUSIONS: This study in two German bakeries shows that preventive measures to reduce contact to allergens have not been sufficiently realised. Relevant alpha-amylase exposure occurred at low dust levels illustrating that dust measurements are not adequate to control alpha-amylase exposure. For fungal alpha-amylase an additional threshold limit should be established.

Aspergillus oryzae↗
PubMed2001

[Occupational exposure to chemicals in the manufacture of rubber tires].

The work environment of the rubber industry company, producing various types of tires, was assessed and the workers of the plant were included in a cohort study of mortality. Concentrations of twenty chemical substances at 137 workposts were measured by employees of the plant laboratory and the sanitary and epidemiological station in 1981-1996. The mean values and concentration ranges were determined by departments and workposts. The excess of threshold limit values was analyzed. The workposts with exposure to agents possibly carcinogenic to humans were identified. The analysis performed will render it possible to calculate doses of cumulative exposure to given compounds among workers covered by the epidemiological study.

Carcinogens↗
PubMedDate not supplied

Nasal function in self-reported chemically intolerant individuals.

Nasal function has not yet been investigated under controlled exposures in individuals with self-reported Multiple Chemical Sensitivity (sMCS). Therefore, anterior rhinomanometry and acoustic rhinometry were applied in 12 individuals with sMCS, and 12 age-matched controls. The sMCS individuals and controls were selected on the basis of a standardized questionnaire. Controlled 4-hr exposures to ethylbenzene and 2-butanone were performed during 4 sessions. Exposures were close to the current German threshold limit values, and they approximated odor thresholds. Subjects with sMCS had a significant decrease in the flow value in anterior rhinomanometry, independent of substance and doses, compared with controls. This result suggests somatic reactions to the exposure. The result must be confirmed in additional studies, and pathophysiological examinations must be performed. For these investigations, anterior rhinomanometry was usable, but acoustic rhinometry can be recommended only after sufficient standardization has occurred. Furthermore, biochemical parameters of nasal mucosa must be considered.

Administration, Intranasal↗
PubMed1989

Ordering of metal-ion toxicities in different species--extrapolation to man.

Our previous attempts to predict the toxicities of 24 metal ions for a given species, using physicochemical parameters associated with the ions, are summarized. In our current attempt we have chosen indicators of toxicity for biological systems of increasing levels of complexity--starting with individual biological molecules and ascending to mice as representative of higher-order animals. The numerical values for these indicators have been normalized to a scale of 100 for Mg2+ (essentially nontoxic) and 0 for Cd2+ (very toxic). To give predicted toxicities to humans, extrapolations across biological species have been made for each of the metal ions considered. The predicted values are then compared with threshold limit values (TLV) from the literature. Both methods for predicting toxicities have their advantages and disadvantages, and both have limited success for metal ions. However, the second approach suggests that the TLV for Cu2+ should be lower than that currently recommended.

Animals↗
PubMedDate not supplied

Evaluation of odor and sensory irritation thresholds for methyl isobutyl ketone in humans.

Odor and irritation sensitivity for methyl isobutyl ketone (MIBK) was evaluated by obtaining olfactory detection thresholds and irritation (lateralization) thresholds, as well as perceived odor intensity and irritation ratings for three predetermined concentrations of MIBK, acetone, and phenylethyl alcohol. Subsequently, perceived annoyance ratings for the three concentrations were measured for 25 of the 40 volunteers. The mean odor detection threshold for MIBK was 10 ppm, and mean lateralization threshold was 8874 ppm. Calculating the fifth percentile for lateralization thresholds revealed that 95% of the sample population did not experience sensory irritation at or below 1802 ppm. Thus, while odor thresholds were well below the current recommended exposure limits (50 ppm, threshold limit value; 75 ppm short-term exposure limit, American Conference of Governmental Industrial Hygienists), irritation thresholds were significantly higher. Odor and irritation intensity ratings for the chemicals increased with increasing concentrations and were higher for MIBK than for acetone. However, when the affective component of the irritation response (annoyance) was rated separately from the sensory component (perceived irritation), no significant differences were found between the irritancy of MIBK and acetone, suggesting that negative hedonic evaluations of MIBK (perhaps based on odor unfamiliarity) contributed to ratings of perceived irritation. These results validate coupling affective and sensory ratings to more effectively examine the human response to volatile stimuli. Results indicate that intranasal sensory irritation from MIBK will not be experienced at or near current exposure levels. Notably, the best predictors of perceived irritation to high concentrations of MIBK were those measures related to its odor, not to the threshold for sensory irritation, suggesting that negative responses to MIBK involve reactions to olfactory properties.

Adaptation, Physiological↗
PubMed2002

[Occupational exposure of whole-body vibration in Poland].

Occupational exposure to whole-body vibration may cause health risk. Thus it is important to know the sources of vibration and the number of exposed workers. The aim of the study was to evaluate the number of men and women exposed to whole-body vibration in Poland. The results of the study indicate that almost 50,000 workers are exposed to vibration exceeding the threshold limit values.

Adult↗
PubMedDate not supplied

Modeling aggregate exposures to glycol ethers from use of commercial floor products.

Computer modeling of aggregate exposure provides the capability to estimate the range of doses that can occur from product use and to understand the relative importance of different routes of exposure. This paper presents an assessment of aggregate occupational exposure to two glycol ethers used as solvents in floor maintenance products for industrial and institutional facilities, using a simulation tool named PROMISE. Three commercial floor-care products were assumed to be applied in sequence--a floor stripper, then a floor cleaner, and lastly a protective coating. The glycol ethers modeled were ethylene glycol butyl ether (EGBE) in the floor stripper and in the floor cleaner, and dipropylene glycol methyl ether (DPGME) in the coating. Modeling uncertainty was assessed through a comparison of the PROMISE inhalation exposure estimates with those from an independent model (MCCEM), and parameter uncertainty was investigated using PROMISE software's Monte Carlo simulation capabilities. Modeling results indicated that inhalation is the dominant exposure route. The predicted average air concentration and inhalation dose from PROMISE agreed with the second model (MCCEM) within 10%. Monte Carlo simulation indicated that the upper end of the aggregate-dose distribution for the scenario was more than 50% higher than the value of the point estimate. The modeled 8-h TWA concentrations for EGBE and DPGME were lower than the corresponding permissible exposure limits American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values (TLV) by at least a factor of 20, indicating that under the assumed conditions workplace exposures to glycol ethers are below levels of concern.

Adult↗
PubMed2001

Assessing interaction thresholds for trichloroethylene in combination with tetrachloroethylene and 1,1,1-trichloroethane using gas uptake studies and PBPK modeling.

The volatile organic solvents trichloroethylene (TCE), tetrachloroethylene (perchloroethylene, PERC), and 1,1,1-trichloroethane (methylchloroform, MC) are widely distributed environmental pollutants and common contaminants of many chemical waste sites. To investigate the mode of pharmacokinetic interactions among TCE, PERC, and MC and to calculate defined "interaction thresholds", gas-uptake experiments were performed using a closed-chamber exposure system. In each experiment, two rats (Fischer 344, male, 8-9 weeks old) were exposed to different initial concentrations of TCE, PERC, and MC, applied singly or as a mixture, and their concentration in the gas phase of the chamber was monitored over a period of 6 h. A physiologically based pharmacokinetic (PBPK) model was developed to test multiple mechanisms of inhibitory interactions, i.e., competitive, non-competitive, or uncompetitive. All mixture exposure data were accurately described by a system of equations in which a PBPK model was provided for each chemical and each was regarded as an inhibitor of the others' metabolism. Sensitivity-analysis techniques were used to investigate the impact of key parameters on model output and optimize experimental design. Model simulations indicated that, among these three chemicals, the inhibition was competitive. The PBPK model was extended to assess occupationally relevant exposures at or below the current threshold-limit values (TLVs). Based on 10% elevation in TCE blood levels as a criterion for significant interaction and assuming TCE exposure is set at TLV of 50 ppm, the calculated interaction thresholds for PERC and MC were 25 and 135 ppm, respectively. TLV exposures to binary TCE/PERC mixture were below the 10% significance level. The interaction threshold for TCE and MC co-exposure would be reached at 50 and 175 ppm, respectively. Such interactive PBPK models should be of value in risk assessment of occupational and environmental exposure to solvent mixtures.

Administration, Inhalation↗
PubMed1996

Closed-circuit apparatus for specific inhalation challenges with an occupational agent, formaldehyde, in vapor form.

Specific inhalation challenges are an important tool for confirming occupational asthma. In recent years, we have described two closed-circuit apparatuses that allow exposure to stable and controlled concentrations of particles and isocyanate gases. More recently, we developed a similar apparatus that generates chemicals in vapor form. The aim of this work is to describe its performance in the specific case of formaldehyde. This instrument is made of four parts: a generator as such, an exposure chamber, a monitor, and an automated regulatory system. This apparatus was assessed in four subjects suspected of having formaldehyde-induced asthma or alveolitis. The concentrations of formaldehyde were increased from 0.5 to 1 mg/m3 to 3 mg/m3 keeping the concentration at a value of 3 mg/m3 or less (threshold limit value). The dispersion of obtained values by comparison with the median data (6 values) was as follows: maximum value, 12 to 84%; minimum value, 20 to 58%; interquartile range, 0.13 to 0.9 mg/m3. We observed that target concentrations took a few minutes to be reached, but, once they were obtained, delivered concentrations were stable. The new vapor-delivery apparatus allows us to obtain concentrations of formaldehyde that are close to target concentrations with an acceptable dispersion of values around target concentration. Its use should be extended to other chemicals besides formaldehyde.

Administration, Inhalation↗
PubMed2001

Lognormal model for determining dose-response curves from epidemiological data and for health risk assessment.

A practical method is proposed for determining human dose-response curves based on reasonable assumptions and simplifications. The epidemiological data needed are the fractions of the population suffering an adverse response from exposures to two or more patterns of fluctuating concentrations of a pollutant, and the statistical parameters of each pattern. The method calculates the two parameters of the threshold type dose-response curve of the pollutant, represented by a cumulative lognormal distribution. This distribution was derived from a reasonable statistical model. The calculation does not require any arbitrary safety factors and yields central values. The dose-response parameters then may be used to calculate the health risk rate of exposure to any other fluctuating concentration pattern. Another method is proposed to select appropriate threshold limit values (TLVs) using calculations involving these parameters. Examples are given to illustrate the calculations. Results with hypothetical data gave apparently reasonable results. They showed the importance not only of the geometric mean concentration but also of the geometric standard deviations of both the concentrations and of the dose-response curve, that greatly influence the results. It is believed that results of useful accuracy should be obtained. Health risk rates are readily understood. They are useful for cost-benefit calculations. Relative rates can be used to compare the hazards of different operations and different plants. The method may make possible the development of standards specifying maximum allowable risk rates.

Cost-Benefit Analysis↗
PubMed2001

[Formaldehyde emissions from wooden products and office furniture].

The formaldehyde emission from wood-products (particleboards, particleboards veneered with artificial veneer, laminated particleboard, hard fibreboards, plywood) and office furniture was measured with the use of environmental chamber (0.2 m3, 0.6 m3, 1.0 m3 capacity) in the following conditions: temperature 23 degrees C, relative humidity 45%, 1 air exchange/hour and factor loading 1 m2/m3. Formaldehyde was determined by using colorimetric methods. Among the tested products, hard fibreboards, plywood and almost all of the enriched particleboards should not contaminate indoor air with formaldehyde over its threshold limit values. The tested office furniture fulfill of the hygienic requirements.

Air Movements↗
PubMed1999

Liver damage among shoe repairers.

BACKGROUND: The risk of hepatotoxicity in the shoe industry has already been suggested, however, there has been no investigation among the craftsmen who repair shoes. METHODS: A group of 33 shoe repairers who work in supermarkets, and who use the same glues which contain mixtures of potentially hepatotoxic solvents were identified. A control group of 61 workers not exposed to hepatotoxic substances was also examined. All participants completed a questionnaire designed to identify potential risk factors and the main non-occupational confounding factors for hepatotoxicity. Laboratory tests, commonly used in clinical practice, were done to check whether they were useful markers of hepatotoxicity due to exposure to solvent mixtures, and to investigate which tests should be used in the screening campaigns. RESULTS: The exposed workers had a higher prevalence of elevated mean alanine aminotransferase (ALT), aspartate aminotransferase (AST), conjugated bilirubin (P=0.0001), and alkaline phosphatase (AP) (P=0.004) than controls did. The number of workers who had values outside the upper limit of normal for our laboratory was significantly higher (ALT P=0.034, AST P=0. 037, conjugated bilirubin P=0.014). Exposed workers all had a ratio of ALT to AST greater than 1, with a mean of 1.5; it was > 1.6 in more than half the exposed workers. CONCLUSIONS: The findings suggest that there is the possibility of liver involvement among even asymptomatic shoe repairers, and that periodic liver screening may be useful; furthermore, use of these tests (especially the ratio of ALT to AST) for craftsmen who repair shoes, and are exposed to solvent mixtures, is advisable even when environmental monitoring indicates levels below the threshold limit values (TLVs).

Acetates↗
PubMed2005

Exposure to fuel-oil ash and welding emissions during the overhaul of an oil-fired boiler.

The health effects of exposure to vanadium in fuel-oil ash are not well described at levels ranging from 10 to 500 microg/m(3). As part of a larger occupational epidemiologic study that assessed these effects during the overhaul of a large oil-fired boiler, this study was designed to quantify boilermakers' exposures to fuel-oil ash particles, metals, and welding gases, and to identify determinants of these exposures. Personal exposure measurements were conducted on 18 boilermakers and 11 utility workers (referents) before and during a 3-week overhaul. Ash particles < 10 microm in diameter (PM(10), mg/m(3)) were sampled over full work shifts using a one-stage personal size selective sampler containing a polytetrafluoroethylene filter. Filters were digested using the Parr bomb method and analyzed for the metals vanadium (V), nickel (Ni), iron (Fe), chromium (Cr), cadmium (Cd), lead (Pb), manganese (Mn), and arsenic (As) by inductively coupled plasma mass spectrometry. Nitrogen dioxide (NO(2)) was measured with an Ogawa passive badge-type sampler and ozone (O(3)) with a personal active pump sampler.Time-weighted average (TWA) exposures were significantly higher (p < 0.05) for boilermakers than for utility workers for PM(10) (geometric mean: 0.47 vs. 0.13 mg/m(3)), V (8.9 vs. 1.4 microg/m(3)), Ni (7.4 vs. 1.8 microg/m(3)) and Fe (56.2 vs. 11.2 microg/m(3)). Exposures were affected by overhaul time periods, tasks, and work locations. No significant increases were found for O(3) or NO(2) for boilermakers or utility workers regardless of overhaul period or task group. Fuel-oil ash was a major contributor to boilermakers' exposure to PM(10) and metals. Vanadium concentrations sometimes exceeded the 2003 American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value.

Adult↗
PubMed2002

The psychological effects of exposure to mixed organic solvents on car painters.

PURPOSE: Interest in diseases of the nervous system resulting from occupational exposure to mixed organic solvents has greatly increased. The aim of our study was to identify preclinical effects of low-level chronic solvent exposure on the central nervous system in car painters by assessing their cognitive performance. METHODS: This psychological study involved 169 clinically healthy male volunteers (84 car painters and 85 controls) and is part of a comprehensive study investigating effects of solvent exposure. The test battery included paper-pencil tests (vocabulary test, block design test, c.i., d2 test), computer-based tests (digit span test, simple-choice reaction time test), and a questionnaire to assess the participants' mental state. RESULTS: Car painters with long-term exposure to solvents showed psychological deviations such as deficits in concentration, memory and reaction time compared to unexposed subjects. The significant differences between the two groups were confirmed by multivariate statistical analysis. CONCLUSIONS: Our study displayed psychological effects associated with long-term solvent exposure in concentrations below German threshold limit values. These findings emphasize the necessity to promote the resolute compliance with occupational safety and health regulations in affected companies.

Adult↗
PubMed2002

[Biologic factors hazardous to health: classification and criteria of exposure assessment].

Occupational biohazards include not only factors that have long been known (viruses, bacteria, fungi, parasites), but also agents exerting allergic and toxic effects, which are directly responsible for the development of various diseases in many occupational groups. Numerous agents of this group (allergens, microbial toxins, pollen allergens and allergens of animal origin) are components of bioacrosols--potential hazards inducing occupational respiratory diseases among farmers and people involved in other occupations. Contrary to the majority of chemical and physical factors, neither commonly approved criteria for assessing exposure to biological factors, nor threshold values and methodological recommendations are as yet available. The lack of these criteria renders it difficult to implement in Poland and in other countries Directive 2000/54/EC on the protection of workers against the risk of occupational exposure to biohazards, issued by the European Community. The Institute of Rural Medicine in Lublin has drafted the proposals for threshold limit values of occupational exposure to bioaerosols associated with plant and animal dusts, including: mesophilic bacteria, Gram-negative bacteria, thermophilic actinomycetes, fungi and bacterial endotoxins. These proposals could be considered as a starting point for developing appropriate facultative standards that would facilitate the practical implementation of the aforesaid Directive. Meantime it is essential to be strict in following the binding concentration limits of the plant and animal dusts in the air.

Aerosols↗
PubMed1995

[Nitrous oxide exposure of operating room personnel in intubation anesthesia].

INTRODUCTION: Epidemiological studies have shown that trace concentrations of inhalation anaesthetics polluting the air of operation theatre could have adverse effects on the personnel's health. Nitrous oxide (N2O) oxidizes vitamin B12 and thus decreases DNA production by inactivation of methionine synthase. Therefore, US and most European health authorities recommend threshold values to protect against potential health risks. These values range from 25 ppm to 100 ppm, expressed as time-weighted averages (TWA). There is a lack of data concerning measurements of trace concentrations under defined conditions. The aim of this study was to quantify levels of N2O in an operating theatre (OT) under modern working environment conditions. METHODS: Trace concentrations of N2O were determined in the OT at three personnel-related and three potential leakage related points and TWA's were calculated. Trace concentrations of N2O were measured directly by means of a highly sensitive photoacoustic infrared spectrometry analyser. The lower detection limit was 0.03 ppm. RESULTS: Values were below 100 ppm TWA at personnel-related locations. NIOSH 25 ppm threshold limit value was exceeded several times. Significant differences between location surgeon and anaesthetist and auxiliary nurse were detected (p < 0.05, Wilcoxon test). CONCLUSION: Exposure to N2O in a climatised OT is determined by several factors: 1. Efficacy of the air-conditioning with 20 changes per hour without recirculation, 2. OT size, 3. low leakage anaesthesia machine, and 4. avoidance of intermittent nitrous oxide supply during induction. Due to these factors, most measured values are below threshold values. In case of other concepts of room design such as ventilation and size, measured values may be higher.

Adult↗