Biomedical subjects

A Vyskocil

Publications and source records attributed to A Vyskocil.

At least 19 recordsLinked to original sources

PubMed2003

Effects of peak concentrations on the neurotoxicity of styrene in volunteers.

The manufacture of fibreglass reinforced plastic products may give rise to substantial peak exposures to styrene. Such exposure patterns need further consideration in terms of styrene neurotoxicity. The aim of this study was to evaluate the neurotoxic effects of short-term peak exposures in volunteers, at levels respecting the Quebec occupational exposure limits (8 hours time weighed average of 213 mg/m3 and 15 min average of 426 mg/ m3). The volunteers had not been previously exposed to styrene and they had no documented exposure to known neurotoxicants during the study. Twenty-four volunteers were exposed to five exposure scenarios during 6 hours: a, stable exposure to 106 mg/m3; b, variable exposure with a mean concentration of 106 mg/m3 with four 15 min peaks mounting up to 213 mg/m3; c, stable exposure to 213 mg/m3; d, variable exposure with a mean concentration of 213 mg/m3 and four peaks of 426 mg/m3 and e, two stable exposures to 5 mg/m3 (control). Before and after each exposure scenario, volunteers were submitted to a battery of sensory tests (visual and olfactory), neuropsychological tests (reaction time, attention, memory, psychomotor function), and self-evaluation questionnaires (mood and symptoms) in a test-retest design. The results show that the different exposure scenarios involving peak exposures did not influence either the performance to any test or subjective signs and symptoms. However, due caution must be exercised in extrapolation of the current results to occupational exposure since only acute exposures were tested and volunteers were at rest during exposure, which resulted in lower doses than those experienced by physically active workers.

Administration, Inhalation↗

PubMed2001

Environmental exposure of small children to polycyclic aromatic hydrocarbons.

OBJECTIVES: The aim of the study was to assess the intake (by various routes of exposure) of polycyclic aromatic hydrocarbons (PAH) by children living in a Czech city, and its effect on excretion of 1-hydroxypyrene (1-OHP) in summer and winter periods. METHODS: Four groups of children (3-6 years old) were chosen: (1) two groups from a kindergarten situated in the city center with a higher traffic density ("polluted" area); (2) two groups from a kindergarten situated in a green zone of the same city ("non-polluted" area). Food consumption was recorded in all children and PAH intake from foodstuffs was estimated. Ambient air samples were collected from the playground and inside the kindergartens. Soil samples were collected too. Morning and evening urine samples were collected during sampling days. RESULTS: In both seasons, the mean outdoor total PAH concentration (sum of 12 individual PAH) in the -polluted" area was approximately three-times higher than that in the "non-polluted" area. Indoor concentration in the "polluted" area was more than six-times higher than that in the "non-polluted" area in summer, and almost three-times higher in winter. The same trend was observed for pyrene and for the sum of carcinogenic PAH. The contribution to the total pyrene absorbed dose from food consumption was much more important than that from inhalation and from ingestion of soil dust. Significantly higher urinary concentrations of 1-OHP (evening samples) were found in children from the "polluted" kindergarten in both seasons. The number of significant relationships between 1-OHP and pyrene absorbed dose was weak. CONCLUSIONS: Food seems to be the main source of total pyrene and total PAH intake in small children, even under relatively higher air PAH exposure in the city. Estimated pyrene ingestion from soil had a negligible contribution to the total pyrene absorbed dose. Urinary 1-OHP seems to be an uncertain (non-sensitive) marker of the environmental inhalation exposure to pyrene (PAH) if the pollution of air by pyrene (PAH) is not excessive and the pyrene (PAH) dose by this route is much less than by ingestion. Usefulness of the urinary 1-OHP as an indicator of overall environmental exposure to PAH needs further investigation.

Child↗

PubMed2000

Assessment of multipathway exposure of small children to PAH.

The aim of study was to assess the uptake of polycyclic aromatic hydrocarbons (PAH) by children living in a city and its effect on 1-hydroxypyrene (1-OHP) excretion. Two groups of children (n=11 and 13; 3-6 years old) were chosen: (1) a group from a kindergarten situated near a road with a high traffic density ('polluted' area); (2) a group from a kindergarten situated in a green zone ('non polluted' area). Food consumption was recorded in all children and PAH uptake from foodstuffs was estimated. Ambient air samples were collected on the playground and indoor of kindergartens during 3 days in summer 1997. Soil samples were collected on the playground. Urine samples were collected in the morning and in the evening. Mean outdoor total PAH concentration (sum of 12 individual PAH) in 'polluted' area was 12 times higher than that in 'non polluted' area (22.9 vs. 1.9 ng/m(3)). However, indoor concentrations were similar (3.0 vs. 2.1 ng/m(3)). The same trend was observed for pyrene concentrations. The contribution to the total pyrene absorbed dose from food consumption (estimated daily absorbed dose of 167 and 186 ng, respectively, in 'polluted' and 'non polluted' area) was much more important than that from inhalation (8.4 and 5.4 ng, respectively) in both areas. The estimated daily absorbed doses of pyrene from the soil were 0.061 and 0.104 ng in 'polluted' and 'non polluted' kindergarten, respectively, which correspond to 0.032 and 0.059% of the total absorbed dose. Higher urinary concentrations of 1-OHP were found in children from 'polluted' kindergarten. In conclusion, the food seems to be a main source of the total pyrene and total PAH uptake in small children, even under a relative high PAH air exposure in the city. Pyrene concentration in soil had a negligible contribution to the total pyrene absorbed dose. Usefulness of the urinary 1-OHP as an indicator of the environmental exposure to PAH needs further research.

Journal Article↗

PubMed2000

Proposal for reference concentrations (RfC) for inhalation exposure to methanol.

A tentative reference concentration (RfC) for methanol in ambient air, i.e. an exposure concentration below which adverse effects are not expected to occur, was derived from the analysis of the toxicological data available in the literature. Well-documented studies that correlate environmental levels of methanol with observed toxic effects have not been found in the literature, nor have any long-term epidemiological studies of chronic low-level occupational exposure been found. Assessment of RfC for acute inhalation exposure is based on a human study (n=26 subjects) with a 'tentative' NOAEL of 262 mg/m(3). The calculated RfC for 1 h exposure is 104.8 mg/m(3). The RfC is given a low confidence rating as there was only one methanol concentration used. A well designed study on monkeys served as the basis for the assessment of RfC for chronic inhalation exposure. In this study, 13.1 and 131 mg/m(3) were considered as NOAEL and LOAEL, respectively. The calculated RfC is 0.38 mg/m(3). The overall database is weak, lacking data on reproductive and developmental endpoints in human or non-human primates. Nevertheless, the RfC is given a medium confidence rating because of the strength of the principal study.

Journal Article↗

PubMed2000

[Polycyclic aromatic hydrocarbons. II. Toxic effects].

Polycyclic aromatic hydrocarbons (PAH) represent dangerous environmental pollutants. Many of them have toxic and carcinogenic potential. Presented work summarizes most of available data on the absorption, metabolism and elimination of PAH. The second part of article contains descriptions and evaluations of toxicological studies and epidemiological investigations and provides conclusions, where possible, on the relevance of toxicity and toxicokinetic data to public health. In the third part of article, the populations with higher susceptibility to exposure to PAH are described and the influences of chemical interaction of PAH to biological effects are mentioned.

Animals↗

PubMed2000

[Polycyclic aromatic hydrocarbons. Biological indicators of exposure and possibilities of prevention].

Polycyclic aromatic hydrocarbons (PAH) represent an extensive group of ubiquitous environmental pollutants disposing of a considerable toxic and carcinogenic potential. According to the IARC data (International Agency for Research on Cancer), PAH represent the largest group of chemical carcinogens produced during combustion, pyrolysis and pyrosynthesis of organic matter. PAH can be identified in atmosphere, water, soil, food and other materials which are in daily contact which the general population. Presented work summarizes most of available data on the biological markers used to identify or quantify the exposure to PAH and on the biological markers used to characterize the effects caused by PAH. The digest of possibilities of reduction toxic effects of PAH concludes the work.

Animals↗

PubMed1999

Environmental contamination and human exposure to manganese--contribution of methylcyclopentadienyl manganese tricarbonyl in unleaded gasoline.

The organomanganese compound MMT (methylcyclopentadienyl manganese tricarbonyl), an antiknock additive in unleaded gasoline, has been used in Canada since 1976. Indeed, Canada is the only country where MMT is almost exclusively used. In October 1995, by court decision the Environmental protection Agency (EPA) granted Ethyl's waiver for the use of MMT in the United States. Paradoxically, in 1997 the federal government of Canada adopted a law (C-29) that banned both the interprovincial trade and the importation for commercial purposes of manganese-based substances, including MMT. However, MMT is currently widely used in Canada because of substantial stockpiling, and six Canadian provinces are challenging the law in the courts. Moreover, MMT has been approved for use in Argentina, Australia, Bulgaria, Russia, and conditionally, in New Zealand. It has been suggested by some scientists that combustion of MMT may be a significant source of exposure to inorganic Mn in urban areas. The crucial question is whether Mn contamination from industrial sources combined with the additional contamination that would result from the widespread use of MMT would lead to toxic effects. Our research efforts have attempted to assess the environmental/ecosystem Mn contamination arising from the combustion of MMT in abiotic and biotic systems as well as human exposure. The experimental evidence acquired so far provides useful information on certain environmental consequences of the use of MMT as well as raising a number of questions. Our results gave evidence indicating that roadside air, soils, plants, and animals may be contaminated by Mn. As well, some specific groups of the population could have a higher level of exposure to Mn. Nevertheless, the levels of exposure remain below international guide values. Further studies and further characterization of dose-response relationships are thus needed to provide successful implementation of evidence-based risk-assessment approaches.

Canada↗

PubMed1999

[Polycyclic aromatic hydrocarbons. I. Environmental contamination and environmental exposure].

Polycyclic aromatic hydrocarbons (PAHs) represent danger ubiquitous environmental pollutants. A lot of them have toxic and carcinogenic potential. Presented work summarises most of available data describing properties, origin and occupational and non-occupational sources of PAHs. Contamination of environment is described separately for air, water, soil, sediments and food. Possibilities of occupational and non-occupational exposure of persons are discussed and populations with potentially high exposures to PAHs are defined. The work is concluded by digest of regulations and guidelines regarding environmental contamination of PAHs.

Environmental Pollutants↗

PubMed1998

Peroxyacetyl nitrate: review of toxicity.

PAN is one of a class of common air pollutants formed by the action of sunlight on volatile organic compounds and nitrogen oxides. No toxicokinetic studies have been found in the available literature. The acute toxicity of PAN is less than that of ozone, similar to NO2 and higher than SO2. The LC30, in mice and rats were 718-743 mg/m3 (for 2 h) and 470 mg/m3 (for 4 h), respectively. Following acute exposure, severe lung lesions and, at the higher levels, damage to the epithelium of upper parts of the respiratory tract were found in animals. It seems that concentrations of 1.19-1.49 mg/m3 lie not far from the threshold required for pulmonary function effects in sensitive individuals. However, these PAN concentrations are well above the maximum ambient concentrations usually experienced within the USA and Canada (0.003-0.078 mg/m3). It appears unlikely that present ambient PAN concentrations would affect pulmonary functions responses to ambient ozone. In human, the lowest level causing eye irritations was 0.64 mg/m3 for 2 h. Concentrations of 0.99 and 4.95 mg/m3 were identified as no-observed-effect level (NOEL) and no-observed-adverse-effect level (NOAEL) for pathological and histological changes in the respiratory system (nasal passages) of rats during subchronic exposures to PAN, but were not considered to be relevant to derivation of a RfC for chronic inhalation exposure. PAN is a weak point mutagen or clastogen. The data are not sufficient to evaluate its carcinogenicity. No study was found which could be used for the derivation of a RfC for acute or chronic inhalation exposure to PAN.

Administration, Inhalation↗

PubMed1998

[Chemical load in the population and its evaluation].

Human health is determined by the interplay between heredity and the environment. Air, water, food and soil contain chemical, physical and biological agents some of which are known to be harmful to health. Chemical substances that pose the risk to human health and safety and to the environment are subject to governmental regulation. The regulatory decision-making process and regulatory actions are based on two distinct elements: risk assessment and risk management. Air pollution (outdoor, indoor) is a world problem afflicting densely populated urban centers and heavily industrialised areas. Industrialization and the widespread use of chemicals coupled with modern intensive agricultural practices have raised a global concern about the contamination of soil and water. Three categories of environmental chemical contaminants generally occur in food--natural and synthetic organic compounds and traces of toxic metals. Human health protection against chemical exposure can be realised in three ways. Environmental monitoring assesses exposure to a chemical agent by measuring its concentration in the environment (i.e., air, soil, food, water). Biological monitoring assesses internal exposure to a chemical agent by measuring the chemical, its metabolites or nonadverse biological response in body fluids, tissues, expired air or excreta. Health surveillance entails the periodic medical examinations of exposed humans with the purpose of protecting health and preventing disease.

Environmental Health↗

PubMed1998

[Biological monitoring of chemical exposure].

In this paper we described the biological monitoring as a capable exposure assessment tool that has provided important information used in public health decisions. Biological monitoring is based on determination of biological markers of exposure which are presented as the quantity of a chemical substance or its metabolites or as the deviation of biological parameters (enzyme activity etc.) induced by this substance in exposed humans. The greatest advantage of biological monitoring is the fact that the biological marker of exposure is more directly related to the adverse effects than any environment measurement. Another advantage of biological monitoring is based on the reality that the nonoccupational background exposure (leisure activity, residency, dietary habits, smoking, etc.) may also be expressed in the biological level. Biological parameters can be unfortunately affected by various factors that influence the fate of xenobiotic in vivo. The "BEL" (BTV-biological tolerance value for occupational exposures) is defined as the maximum permissible quantity of a chemical substance or its metabolites or the maximum permissible deviation from the norm of biological parameters during or after exposure. It should be subject to regular revision in the light of new scientific data.

Environmental Exposure↗

PubMed1997

A study of ethylene glycol exposure and kidney function of aircraft de-icing workers.

Ethylene glycol levels were measured in 154 breathing zone air samples and in 117 urine samples of 33 aviation workers exposed to de-icing fluid (basket operators, de-icing truck drivers, leads and coordinators) studied during 42 worker-days over a winter period of 2 months at a Montreal airport. Ethylene glycol as vapour did not exceed 22 mg/m3 (mean duration of samples 50 min). Mist was quantified at higher levels in 3 samples concerning 1 coordinator and 2 basket operators (76-190 mg/m3, 45-118 min). In 16 cases workers' post-shift or next-morning urine contained quantities of ethylene glycol exceeding 5 mmol/mol creatinine (up to 129 mmol/mol creatinine), with most of these instances occurring in basket operators and coordinators, some of whom did not wear paper masks and/or were accidentally sprayed with de-icing fluid. Diethylene glycol was also found in a few air and urinary samples at levels around one tenth those of ethylene glycol. Urinary concentrations of albumin, beta-N-acetyl-glucosaminidase, beta-2-microglobulin and retinol-binding protein were measured and compared over various periods, according to subgroups based on exposure level and according to the frequency of extreme values. These analyses did not demonstrate acute or chronic kidney damage that could be attributed to working in the presence of ethylene glycol. In conclusion, this study does not suggest important health effects of exposure to de-icing fluid in this group of workers. Potential for overexposure exists, however, in certain work situations, and recommendations on preventive measures are given. In addition, these results suggest that other routes of absorption than inhalation, such as the percutaneous route, may be important and that urinary ethylene glycol may be a useful indicator of exposure to ethylene glycol.

Acetylglucosaminidase↗

PubMed1997

Environmental exposure to polycyclic aromatic hydrocarbons in Czech Republic.

1 Objectives of this study were (1) to compare concentrations of individual polycyclic aromatic hydrocarbons (PAH) in air of polluted and nonpolluted area of Czech Republic during winter and summer periods and (2) to verify if urinary 1-hydroxypyrene (1-OHP), as supposed practical biological marker, permits the assessment of spacial and temporal variations in environmental PAH exposure. 2 The study population consisted of three groups: (1) a group of 22 physical exercise students who regularly train outside, from the university situated in a polluted town, spending 14 days in winter and 14 days in summer in 'non-polluted' mountains; (2) a control group of 22 residents from the town and (3) a control group of 18 residents from the mountains. 3 The total PAH concentrations (sum of 13 individual PAH) were 19.3 and 104.6 ng/m3 in town and in mountains, respectively, during summer and 86.6 and 261 ng/m3 during winter. 4 Median 1-OHP levels ranged between 0.03 and 0.13 mumol/mol creatinine for controls and between 0.04 and 0.12 mumol/mol creatinine for students. No relationship was found between pyrene levels in air and group means of urinary 1-OHP. Our results show that other factors (probably PAH in food) contribute in masking air pollution influence on urinary 1-OHP levels in subjects non-occupationally exposed to PAH.

Adult↗

PubMed1995

Urinary excretion kinetics of 1-hydroxypyrene in volunteers exposed to pyrene by the oral and dermal route.

Two well-informed human volunteers were exposed to 500 micrograms pyrene by ingestion and by dermal application, in two separate experiments. Urinary measurements of 1-hydroxypyrene (1-OHP) were performed on all micturitions taken at intervals of 0.5-4 h for a total period of 48 h after dosing. Following the absorption phase, 1-OHP is excreted with a first order apparent half-life of approximately 12 h for both volunteers and both exposure routes. These results compare well with other previously published studies. A more refined analysis of the data was performed using a two-compartment toxicokinetic model for 'pyrene' (its fraction eventually excreted as 1-OHP). As it was found that a classical first-order system did not adequately fit the data, a non-linear term was introduced in the model for the elimination of urinary 1-OHP. Computer iteration performed on the oral absorption data allowed an estimation of various toxicokinetic parameter values. The mean intercompartmental exchange (k12 and k21) and elimination coefficients were 0.010, 0.006 and 0.012 min-1, respectively. The first two values compare well with those previously published for the rat, whereas the latter is smaller in humans. These values were used to satisfactorily simulate the experimental data for both routes of exposure, adjusting only for kabs which was estimated at 0.014 and 0.0029 min-1 for the oral and dermal exposure, respectively. The proposed model generates new hypotheses on the metabolism of pyrene. The information collected will contribute to the validation of the utilisation of 1-OHP as a biological indicator of exposure to pyrene.

Administration, Cutaneous↗

PubMed1995

Patterns of 1-hydroxypyrene excretion in volunteers exposed to pyrene by the dermal route.

The urinary excretion profiles following exposure to pyrene were established in one psoriasic patient under treatment with a coal tar-based shampoo and in two other volunteers exposed to a single dose of 100 microliters creosote and, in a separate experiment, to five consecutive daily dermal applications of 500 micrograms pyrene on 200 cm2 of the inner face of the forearms. Timed micturitions were collected for up to 48 h following exposure. Both in the psoriasic patient and in the volunteers exposed to creosote, the excretion peaks between 10 and 15 h after application and first-order apparent half lives of 11.5-15 h can be calculated for the elimination phase. Compatible with these observations, repeated exposure to pyrene in the volunteers causes an increase in peak and trough urinary 1-hydroxypyrene (1-OHP) values for the first few days following the first exposure. These results suggest that the difference between beginning-of-shift/beginning of work week and beginning-of-shift/end of work week 1-OHP excretions should reflect the average exposure of the week in workers having a constant exposure to pyrene. The difference between the beginning- and end-of-shift excretion values of a given day should reflect the exposure of that day but the maximum excretion would be attained a few hours after termination of exposure.

Administration, Cutaneous↗

PubMed1995

Background urinary 1-hydroxypyrene levels in non-occupationally exposed individuals in the Province of Québec, Canada, and comparison with its excretion in workers exposed to PAH mixtures.

The urinary excretion of 1-hydroxypyrene (1-OHP) was measured in two reference groups of non-occupationally exposed individuals and in four groups of workers. Two of these groups were exposed to what were considered to be low levels of polycyclic aromatic hydrocarbons (PAH) on the basis that even post-shift 1-OHP excretion values were low (< 2 mumol/mol creatinine). Therefore, urine samples were collected from these workers after a period of > 60 h without occupational exposure which should yield values approaching background levels. Pooling these results with those of the reference groups yielded a total of 140 individuals having a mean (geometric) excretion of 0.08 mumol/mol creatinine and 5th, 50th and 95th percentiles of 0.02, 0.09 and 0.32 mumol/mol creatinine. The mean (geometric) excretion in the 95 nonsmokers and 45 smokers of this pool was 0.07 and 0.12 mumol/mol creatinine, respectively (one-tailed Student t-test, P < 0.001). Both this background excretion and the contribution of smoking appeared small in comparison with the excretion levels observed in some groups of exposed workers. Indeed, creosote workers described in this report had a geometric mean (range) excretion of 1.63 (0.18-10.47) mumol/mol creatinine during their working week. It is concluded that, for the biological monitoring of workers exposed to PAH, urinary 1-OHP appears to be a useful bioindicator for which background environmental contamination or smoking habits can be neglected in most cases.

Air Pollutants↗

PubMed1995

Renal effects in children living in the vicinity of a lead smelter.

A cross-sectional study was carried out to determine whether environmental exposure of children to lead may cause renal effects. The study involved a total of 195 children aged 12 to 15 years. One hundred forty-four children (63 boys and 81 girls) were recruited from two schools in the vicinity of a lead smelter and 51 (25 boys and 26 girls) from a school in a rural area. Compared to their referents, boys and girls from the two schools in the polluted area had significantly higher levels of lead in blood (PbB) but similar levels of cadmium (CdB) and zinc protoporphyrins (ZPP). The functional integrity of the kidney was assessed by measuring the urinary excretion of beta 2-microglobulin, Clara cell protein, retinol-binding protein (RBP), albumin and beta-N-acetyl-D-glucosaminidase. The most significant and consistent finding of the study was that children from the two schools in the polluted area showed a significant elevation of the urinary excretion of RBP that paralleled the level of lead in blood or in the dust collected on the school playgrounds. A similar pattern was observed for the prevalence of elevated values of urinary RBP which increased from 3.9% in the control area up to 17% in the most polluted school. Urinary RBP was found to be associated with PbB (partial r2 = 0.046, P = 0.005) in a stepwise regression analysis testing also the influence of age, sex, CdB, and ZPP. In conclusion, the present study suggests that lead contaminating the environment may cause slight effects on the proximal tubule function in children at exposure levels close to those associated with CNS deficit.

Adolescent↗

PubMed1995

Distribution of nickel in body fluids and organs of rats chronically exposed to nickel sulphate.

1. Male and female rats were given 100 mg Ni L-1 (as nickel sulphate) in drinking water for 6 months. 2. The feeding of nickel was associated with an increased concentration of nickel in body fluids and organs. The highest concentrations of nickel were found in the liver of both male and female rats. In male rats nickel levels decreased in the order: liver > kidney = whole blood = serum > testes > urine. In female rats the decreasing order was similar: liver > kidney = whole blood = serum = plasma > urine > ovaries. 3. No significant differences were found between nickel concentrations in organs (except ovaries), blood and urine of rats exposed for 3 months and those exposed for 6 months indicating the reaching of a steady state of nickel in the rat during long-term exposure. 4. The urinary excretion of the orally administered nickel was only 2% of absorbed dose (supposing 1% Ni absorption).

Administration, Oral↗