Pharmacokinetics and pharmacodynamics of antiulcer agents in llama

Plasma concentration time curves following intravenous (i.v.) administration of 1.5 mg/kg of ranitidine, 0.2 mg/kg, 0.4 mg/kg and 0.8 mg/kg of omeprazole, respectively, were analysed in six llamas. Plasma profiles after i.v. administration of both drugs showed plasma concentrations declining in a biexponential manner with a rapid distribution phase. Pharmacokinetics parameters after ranitidine administration to six llamas showed a mean elimination half-life of 1.53 +/- 0.26 h. The mean volume of distribution (Vdss) in llamas was 1.77 +/- 0.31 L/kg, and mean body clearance in llamas was 0.778 +/- 0.109 L/kg/h. Ranitidine produced only a small transitory (<1 h) decline in acid production when administered i.v. at a dose of 1.5 mg/kg. Omeprazole showed dose-dependent nonlinear pharmacokinetics. The mean half-life of 0.2 mg/kg i.v. omeprazole was shorter than that of 0.4 and 0.8 mg/kg i.v. omeprazole, i.e. 0.61, 0.72 and 1.07 h, respectively. The area under the curve (AUC) and mean residence time (MRT) increased with increasing dose, while clearance decreased as dose increased. The decline in acid production following 0.2 mg/kg i.v. omeprazole was highly variable and did not produce a clinically useful suppression of third compartment acid production. In contrast, both 0.4 mg/kg and 0.8 mg/kg omeprazole i.v. administration significantly reduced third compartment acid production. The reduction in acid production following 0.8 mg/kg omeprazole was not significantly greater than the reduction observed following 0.4 mg/kg dosage. Misoprostol (10 microg/kg) was administered i.v. in an absolute alcohol solution. Two animals collapsed following drug administration. While the side-effects could have been produced by either misoprostol or the alcohol vehicle, the clinical changes were more consistent with an adverse drug reaction. Unfortunately, the limitation of UV detection did not provide the sensitivity needed to quantify the amount of misoprostol in llama plasma, and the pharmacokinetics could not be evaluated.

Repeated exposures to cobalt or chromate on the hands of patients with hand eczema and contact allergy to that metal

The present study aimed at evaluating the effects of daily repeated exposures to low cobalt or chromate concentrations on the hands of patients with hand eczema and cobalt or chromate allergy. For 2 weeks, the patients immersed a finger for 10 min daily into the appropriate metal salt solution in water. During the 1st week, this was a 10 or 50 mg/l cobalt concentration or a 10 mg/l chromate concentration, and, during the 2nd week, a 100 or 200 mg/l cobalt concentration or a 100 mg/l chromate concentration. This regimen elicited a flare of hand eczema only in the chromate-exposed chromate-sensitive patients. During the exposure period, accumulation of cobalt or chromate in the nail was demonstrated. Standardization of chemical methods of quantification of skin exposure to allergens, combined with experimental exposure studies in patients with specific contact allergy, will increase the possibility of providing evidence-based medicine in the area of allergic contact dermatitis in the future.

Nickel-induced cytokine production from mononuclear cells in nickel-sensitive individuals and controls. Cytokine profiles in nickel-sensitive individuals with nickel allergy-related hand eczema before and after nickel challenge

Exposure to nickel is a major cause of allergic contact dermatitis which is considered to be an inflammatory response induced by antigen-specific T cells. Here we describe the in vitro analysis of the nickel-specific T-cell-derived cytokine response of peripheral blood mononuclear cells from 35 nickel-allergic and 30 non-nickel-allergic individuals. Peripheral blood mononuclear cells were stimulated with 10(-4) and 10(-5) mol/l NiSO4 for 6 days and then additionally with ionomycin and phorbol myristate acetate for 24 h. Culture supernatants were analysed for interleukin-4 (IL-4), IL-5, interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha (TNF-alpha) by quantitative ELISA. The analysis showed that the synthesis of IL-4 and IL-5 but not of IFN-gamma or TNF-alpha was significantly higher in the nickel-allergic individuals. The finding of preferential synthesis of Th2 cytokines was somewhat of a surprise, since previous studies have suggested a Th1 response in nickel-mediated allergic contact dermatitis. Subsequently, the nickel-allergic individuals were randomized to experimental exposure to nickel or vehicle in a double-blind design. A daily 10-min exposure of one finger to 10 ppm nickel solution for 1 week followed by 100 ppm for an additional week evoked a clinical response of hand eczema in the nickel-exposed group. Blood samples were drawn on days 7 and 14 after the start of this exposure to occupationally relevant concentrations of nickel. No statistically significant differences were observed in the nickel-induced in vitro cytokine response during the exposure period. Our results indicate the possibility that IL-4 and IL-5 are involved in the pathogenesis of nickel-mediated contact dermatitis.

Seasonal and biological variation of blood concentrations of total cholesterol, dehydroepiandrosterone sulfate, hemoglobin A(1c), IgA, prolactin, and free testosterone in healthy women

BACKGROUND

Concentrations of physiological response variables fluctuate over time. The present study describes within-day and seasonal fluctuations for total cholesterol, dehydroepiandrosterone sulfate (DHEA-S), hemoglobin A(1c) (HbA(1c)), IgA, prolactin, and free testosterone in blood, and estimates within- (CV(i)) and between-subject (CV(g)) CVs for healthy women. In addition, the index of individuality, prediction intervals, and power calculations were derived.

METHODS

A total of 21 healthy female subjects participated in the study. Using a random effects analysis of variance, we estimated CV(g) and total within-subject variation (CV(ti)), i.e., the combined within-subject and analytical variation, from logarithmically transformed data. Analytical variation was subtracted from CV(ti) to give CV(i). CV(i) was estimated from samples taken monthly during 1 year (CV(iy)), weekly during 1 month (CV(im)), and six times within 1 day (CV(id)).

RESULTS

A cyclic seasonal variation was demonstrated for total cholesterol, DHEA-S, HbA(1c), prolactin, and free testosterone. Within-day variation was shown for prolactin and free testosterone. The overall mean values for the group and the variability (CV(iy) and CV(g)) were: 5.1 mmol/L, 13% [corrected], and 12% [corrected] for total cholesterol; 6.6 micromol/L, 20% [corrected], and 49% [corrected] for DHEA-S; 30% [corrected], 7.0% [corrected], and 7.5% [corrected] for HbA(1c)/hemoglobin(total); 2.1 g/L, 5.9%, and 13% for IgA; 136 mIU/L, 58% [corrected], and 63% [corrected] for prolactin; and 5.4 pmol/L, 55% [corrected], and 68% [corrected] for free testosterone.

CONCLUSIONS

Collecting samples at specific hours of the day or times of the year may reduce high biological variation. Alternatively, the number of individuals may be increased and a paired study design chosen to obtain adequate statistical power.

Effects of repeated skin exposure to low nickel concentrations: a model for allergic contact dermatitis to nickel on the hands

We studied the effects of repeated daily exposure to low nickel concentrations on the hands of patients with hand eczema and nickel allergy. The concentrations used were chosen to represent the range of trace to moderate occupational nickel exposure. The study was double-blinded and placebo controlled. Patients immersed a finger for 10 min daily into a 10-p.p.m. nickel concentration in water for the first week, and during the second week into a 100-p.p.m. nickel concentration. This regimen significantly increased (P = 0.05) local vesicle formation and blood flow (P = 0.03) as compared with a group of patients who immersed a finger into water. The nickel concentrations used also provoked significant inflammatory skin changes on sodium lauryl sulphate (SLS)-treated forearm skin of the patients, whereas inflammatory skin changes were not observed in healthy volunteers without hand eczema and nickel allergy, either on normal or on SLS-treated forearm skin. The present study strongly suggests that the changes observed were specific to nickel exposure. Standardized methods to assess trace to moderate nickel exposure on the hands, and the associated effects in nickel-sensitized subjects, are needed.

Nickel concentrations in serum and urine of patients with nickel eczema

This study is a part of the Biological Risk Assessment of Human Metal Sensitisation (BRAHMS) project with the aim of elucidating clinical and physiological effects of repeated exposures to low concentrations of metal allergens. Nickel allergic individuals (n = 35) with hand eczema and healthy controls (n = 30) were included in the study. Both groups had similar levels of nickel in urine, while the level of nickel in serum was significantly lower in nickel allergic individuals compared to controls. Nickel allergic individuals had a significantly lower intake of nickel-rich food items (chocolate, nuts, beans, porridge oats). Serum nickel levels correlated with intake of these foods, suggesting that the difference in serum nickel levels was caused by differences in dietary nickel intake.

Evaluation of a whole cell, p57- vaccine against Renibacterium salmoninarum

A whole cell Renibacterium salmoninarum vaccine was developed using 37 degrees C heat treated cells that were subsequently formalin fixed; this treatment reduced bacterial hydrophobicity and cell associated p57. Coho salmon Oncorhynchus kisutch were immunized with the p57- vaccine by either a combination of intraperitoneal (i.p.) and intramuscular (i.m.) injections or per os. In the first experiment, i.p./i.m. vaccination of coho salmon with p57- cells in Freund's Incomplete Adjuvant (FIA) conferred a statistically significant increase in mean time to death after the salmon were i.p. challenged with 4.1 x 10(6) colony forming units (cfu) of R. salmoninarum. There was no significant difference in response between fish immunized with R. salmoninarum cell surface extract in FIA and those immunized with extracellular protein (ECP) concentrated from culture supernatant in FIA. The i.p. challenge dose resulted in complete mortality of all fish by Day 43. In a second experiment, fish were orally vaccinated with p57- R. salmoninarum cells encased in a pH protected, enteric-coated antigen microsphere (ECAM). Fish were bath challenged with 4.2 x 10(6) cfu ml-1 on Day 0 and sampled at time points of 0 (pre-challenge), 50, 90, or 150 d immersion challenge. Vaccine efficacy was determined by monitoring the elaboration of p57 in the kidneys of vaccinated and control fish. Fish vaccinated orally demonstrated a significantly lower concentration of p57 (p < 0.01) at Day 150 post challenge compared to fish receiving ECAMs alone. Fish receiving p57 cells without ECAM coating also showed a significantly lower p57 level (p < 0.03) versus control. In contrast, fish injected intraperitoneally with the p57- cells or fish fed p57+ R. salmoninarum cells in ECAMs demonstrated no significant difference (p > 0.05) versus controls. In summary, these studies suggest the preliminary efficacy of 37 degrees C treatment of R. salmoninarum cells as an oral bacterial kidney disease vaccine.

Speciation measurements by HPLC-HGAAS of dimethylarsinic acid and arsenobetaine in three candidate lyophilized urine reference materials

Speciation measurements of dimethylarsinic acid (DMA) and arsenobetaine (AsB) in three candidate lyophilized urine reference materials are described. The measurements were based on cation-exchange liquid chromatography coupled to hydride generation atomic absorption spectrometry with on-line digestion of the organic. As species by alkaline persulfate solution aided by ultraviolet radiation. Arsenic concentrations as DMA were significantly different in the three samples. The mean values for the three samples were 4.1 +/- 0.3, 55.3 +/- 1.2 and 134.1 +/- 1.5 micrograms l-1, respectively. No significant differences in AsB concentrations were observed among the three samples. The mean As concentrations as AsB in the three samples were 17.4 +/- 0.4, 17.7 +/- 0.2 and 17.5 +/- 0.3 micrograms l-1, respectively. By off-line digestion of the urine samples, total As concentrations in the three materials were also obtained. The mean values were 23.4 +/- 0.3, 76.6 +/- 1.6 and 151.3 +/- 1.8 micrograms l-1, respectively. These results correlated well with the results obtained by neutron activation analysis in our laboratory (r = 0.999; p < 0.0001).

Inductively coupled plasma mass spectrometric determination of molybdenum in urine from a Danish population

Molybdenum creatinine levels in urine were measured in 128 Danish inhabitants by ICP-MS in order to establish reference intervals of molybdenum in urine for the Danish population as a part of the EURO-TERVIHT project (Trace Element Reference Values in Human Tissues). The Mo concentration was determined using the isotopes 95Mo and 98Mo. The values measured based on 98Mo were about 2% lower than those calculated using 95Mo, a negligible difference in the context of reference values. The limit of detection was 0.2 microgram l-1, the precision was 8.6% and the recovery of added NIST 1643c certified reference material was 94%. The distribution of the data, with and without correction for creatinine concentration, was long-normal. The mean concentration measured was 42.5 micrograms l-1, (3.89 micrograms Mo mmol-1 creatinine) using 95Mo and 41.5 micrograms l-1 (3.81 micrograms Mo mmol-1 creatinine) using 98Mo, with the 95% parametric reference intervals 10.0-124.0 micrograms l-1 (0.89-11.50 micrograms Mo mmol-1 creatinine) and 9.6-122.6 micrograms l-1 (0.84-11.47 micrograms Mo mmol-1 creatinine), respectively. The difference between men and women reached the level of significance only after the values were corrected for the creatinine concentration. There was no influence of age on the Mo concentration. Specific effects of different food and beverage intakes could not be demonstrated, with the exception of a positive correlation between butter consumption and Mo concentration.

Trends in quality assurance of metal determination in clinical chemistry

A summary is given of the main strategies that can be used to obtain high quality results in the determination of metals in clinical chemistry. The trends in quality assurance of metal analyses are discussed.

A DANREF certified reference material for chromate in cement

Two candidate reference materials for chromate in cement were produced in the DANREF network and certified in an interlaboratory study. Fifteen laboratories participated in the interlaboratory study and six different analytical methods were used. The certified values were estimated as the consensus mean of laboratory mean values (outliers excluded). Only results from laboratories using methods relying on chromate speciation were accepted. The certified values (+/- 95% confidence limits) were 0.678 (+/- 0.075) mg CrVI kg-1 dry cement for the low level and 6.04 (+/- 0.28) mg CrVI kg-1 dry cement for the high level. Methods based on total chromium determination gave on average results that were 6.5% higher (both levels). However, the difference between speciation and non-speciation results was significant at the high concentration level only.

Toxic trace element reference levels in blood and urine: influence of gender and lifestyle factors

This study is part of the EURO-TERVIHT project (Trace Element Reference Values in Human Tissues) which aims at establishing reference intervals for trace elements in blood, urine and other human tissues. In this study reference intervals (0.05-0.95 fractiles) were estimated for lead in blood (105-529 nmol/l for men, 80-340 nmol/l for women), manganese in blood (100-271 nmol/l) and arsenic in urine (36-541 nmol/l for men, 21-475 nmol/l for women). Upper reference limits (0.95 fractile) were established for chromium in urine (13 nmol/l), nickel in urine (52 nmol/l) and cobalt in urine (23 nmol/l for men, 31 nmol/l for women). The reference group was a Danish subpopulation (n = 189), age 40-70 years. The influence of gender, age, health status parameters, nutrition and various lifestyle factors was investigated. Urinary arsenic and blood lead levels were found to be higher for men than for women. Arsenic levels also increased with age up to 60 years, and then decreased. Alcohol intake lead to increased arsenic levels in urine as well as blood lead levels. Urinary nickel levels were higher in persons frequently eating porridge and porridge oats.

Identifying denial in stroke patients

The purpose of this study was to test the reliability of an experimental assessment tool for identifying and differentiating between psychodynamic and neurogenic denial in stroke patients. A one-page criterion referenced denial assessment tool was used by interdisciplinary rater teams to evaluate patients with either right or left hemisphere insults. High interrater reliability was obtained. Assessment data indicated that right-CVA patients had higher psychodynamic and neurogenic denial scores than left-CVA patients. Higher psychodynamic denial scores were also observed in the second month post-stroke. The experimental denial assessment tool proved to be a practical way for identifying and differentiating psychodynamic and neurogenic forms of denial. This tool can provide a means for ongoing assessment to support precise nursing diagnoses and promote effective patient-focused care planning throughout the rehabilitation process.

Cryopreservation of channel catfish spermatozoa: Effect of cryoprotectant, straw size, and formulation of extender

Various aspects of the cryopreservation of spermatozoa of channel catfish (Ictalurus punctatus ) were studied in relation to spermatozoa motility. The objectives were to evaluate 1) the efficacy of 5, 10 and 15% of methanol or n,n-dimethyl acetamide (DMA) as cryoprotectants; 2) the acute toxicity of 5, 10 and 15% methanol or DMA; 3) the use of 0.5-ml vs. 0.25-ml straws; 4) the efficacy of 5, 10 and 15% of methanol in Hanks' balanced salt solution (HBSS) or HBSS without glucose, and 5) the use of HBSS with or without 5% methanol. We found that use of 5% methanol as a cryoprotectant resulted in significantly higher post-thaw motility (P = 0.0001) than did 5, 10 or 15% DMA. The use of 5% of either cryoprotectant resulted in significantly higher post-thaw motility (P = 0.0001) than did 10 or 15% of the cryoprotectants. Samples containing 10 or 15% DMA had significantly lower motility (P = 0.0001) after 30 min exposure than did samples containing 5, 10 or 15% methanol. The use of 0.25-ml straws resulted in significantly higher post-thaw motility (P = 0.0001) than that of 0.5-ml straws. No difference was found in post-thaw motility between HBSS with and without glucose as the extenders. Cryopreservation in HBSS without addition of cryoprotectant resulted in post-thaw motility values of about 1%.

Critical evaluation and review of cadmium concentrations in blood for use in occupational health according to the TRACY protocol

Cadmium in blood (B-Cd) may be used to assess recent exposure to cadmium in the working or general environment. In a paper published elsewhere pooled reference values using meta-analysis of B-Cd values in general-population studies were calculated. In the present study tentative references intervals were described which can be used for comparison with data from occupationally exposed groups or individuals. The selection of studies was done according to criteria as published by the international project TRACY. For this purpose, 800 publications covering the period 1983-1992 were reviewed on their suitability for establishing tentative reference intervals. From these 800 publications, four finally met the selection criteria. Most important criteria for selection were the check for contamination during sampling of the blood, the storage and pretreatment procedures, and the existence of internal and external quality control programs. Also, stratifications into sex, smoking habits and occupation were important selection criteria. It turned out that for non-smoking white-collar workers in the age range of 19-65 years, B-Cd values were below 0.8 micrograms/l for most areas. All other groups within this age group, e.g., white collar workers in Japan, blue-collar workers, and smokers tend to have higher B-Cd values in these sequences. Blue-collar workers not clearly exposed to Cd have higher values than white-collar workers, indicating still some minor exposure. It is not clear if this small exposure has an occupational or lifestyle (e.g., diet) origin. Geographical regions also show an influence on B-Cd levels, e.g., values in Japan are higher than elsewhere. This influence may be due to differences in diet. The conclusion will be that reference values for B-Cd in fact are area-dependent.

The disposition of five therapeutically important antimicrobial agents in llamas

The disposition of five therapeutic antimicrobial agents was studied in llamas (Lama glama) following intravenous bolus administration. Six llamas were each given ampicillin, tobramycin, trimethoprim, sulfamethoxazole, enrofloxacin and ceftiofur at a dose of 12 mg/kg, 1 mg/kg, 3 mg/kg, 15 mg/kg, 5 mg/kg, and 2.2 mg/kg of body weight, respectively, with a wash out period of at least 3 days between treatments. Plasma concentrations of these antimicrobial agents over 12 h following i.v. bolus dosing were determined by reverse phase HPLC. Disposition of the five antimicrobial agents was described by a two compartment open model with elimination from the central compartment, and also by non-compartmental methods. From compartmental analysis, the elimination rate constant, half-life, and apparent volume of distribution in the central compartment were determined. Statistical moment theory was used to determine noncompartmental pharmacokinetic parameters of mean residence time, clearance, and volume of distribution at steady state. Based on the disposition parameters determined, and stated assumptions of likely effective minimum inhibitory concentrations (MIC) a dose and dosing interval for each of five antimicrobial agents were suggested as 6 mg/kg every 12 h for ampicillin; 4 mg/kg once a day or 0.75 mg/kg every 8 h for tobramycin; 3.0 mg/kg/15 mg/kg every 12 h for trimethoprim/sulfamethoxazole; 5 mg/kg every 12 h for enrofloxacin; and 2.2 mg/kg every 12 h for ceftiofur sodium for llamas. Steady-state peak and trough plasma concentrations were also predicted for the drugs in this study for llamas.

Sample collection guidelines for trace elements in blood and urine. IUPAC Commission of Toxicology

This paper presents an organized system for element-specific sample collection and handling of human blood (whole blood, serum or plasma, packed cells or erythrocytes) and urine also indicating a proper definition of the subject and sample. Harmonized procedures for collection, preparation, analysis and quality control are suggested. The aim is to assist scientists worldwide to produce comparable data which will be useful on a regional, national and international scale. The guidelines are directed to the elements aluminium, arsenic, cadmium, chromium, cobalt, copper, lead, lithium, manganese, mercury, nickel, selenium and zinc. These include the most important elements measured for their occupational or clinical significance, and serve as examples of principles that will guide development of methods for other elements in the future.

Blood lead in the general population in Poland

Lead concentration in venous blood (Pb-B) was investigated in 1122 inhabitants (including 555 children under 10 years of age) of five Polish towns with no large industrial lead emitters (group I) and in 1246 persons (707 children under 10 years of age) living in the vicinity of zinc and copper mills (group II). The samples were analysed using electrothermal atomic absorption spectrometry (ETAAS) and the performing laboratory participated in the external quality control scheme during the study period (1992-1994). In group I the mean geometric Pb-B concentrations ranged from 23.8 to 48.3 micrograms/l in females, from 42.5 to 76.8 micrograms/l in males and from 29.9 to 62.5 micrograms/l in children. In group II, the mean geometric Pb-B concentrations were significantly higher and ranged from 49.4 to 105 micrograms/l in females, from 98.5 to 149 micrograms/l in males and from 73.7 to 114 micrograms/l in children, the values decreasing as the distance from the source of emission increased. Cigarette smoking was found to bring about a significant increase in Pb-B levels for both males and females. A significant correlation was noted between Pb-B concentrations in mothers and children. The ratio between child and maternal Pb-B concentrations amounted to approximately 1.0 for group I and to about 0.5 for group II. These findings indicate the necessity of undertaking preventive activities over the lead-contaminated areas. However, the lead hazard in Poland seems to be associated with point sources of emission and hence does not concern the whole population.

Geltape method for measurement of work related surface contamination with cobalt containing dust: correlation between surface contamination and airborne exposure

OBJECTIVES

The geltape method is a new method for optical measurement of total amount of dust on surfaces. The objectives were to study the potential applicability of this method to measurements of work related cobalt exposure during painting of plates with cobalt dye.

METHODS

Consecutive series of work related geltape prints were taken from surfaces inside and outside the ventilation cabins of two plate painters during two full working days. The amount of dust picked up by the geltapes was measured optically with a field monitor. Also, personal air samples were collected on filters at the different work processes. In the laboratory the contents of cobalt on the geltape prints and the filters were measured with inductive coupled plasma atomic emission spectroscopy.

RESULTS

The key results were: (a) when the geltape prints were taken from surfaces inside the cabins the optically measured area of the geltapes covered with total dust (area (%)) correlated well with the chemically measured amount of cobalt present on the geltapes. Linear correlation coefficient (R2) was 0.91 for geltape prints taken on the floor and 0.94 for prints taken on the ceiling; (b) the cumulative airborne cobalt exposure, calculated from data on work related exposure by personal sampling, correlated with the area (%) of geltape prints taken from the ceiling of the cabin (R2 = 0.98); (c) the geltape method could be used to distinguish both between work processes with different levels of cobalt exposure, and between plate painters subjected to significant differences in airborne cobalt exposure.

CONCLUSION

The geltape method could produce measures of the work related exposures as well as whole day exposure for cobalt. The geltape results correlated with measurements of personal airborne cobalt exposure. In this industry the profile of exposure is well-defined in time, and it seems reasonable to apply this fast and low cost method in routine exposure surveillance to obtain a more detailed description of the exposure than can be obtained by the use of airborne measurements only.

Human exposure to toxic metals: factors influencing interpretation of biomonitoring results

An important approach to assessment of risk from environmental and occupational exposures is biomonitoring which provides an estimate of the total dose absorbed and gives indirect access to determination of target site concentrations. It is also a tool for assessing residual exposure, when respiratory protection is used. The interest in biological effects from toxic metals has increased during the last decades, as large amounts of metals have been released into industrial areas, and it is estimated that approximately 150,000 Danish workers are exposed to various metals. Since biomonitoring results play an important role in decision-making regarding great health and economic impact, understanding the factors influencing validity of such data is essential. In the present survey, the toxic elements arsenic, cadmium, chromium, cobalt, lead and nickel are used as examples to illustrate the disturbing factors in the interpretation of biomonitoring results. The aim of collecting samples is to obtain a small and representative sample of subjects or of a subpopulation being investigated for specific purposes, e.g. the pollution at Mundelstrup, where arsenic exposure of inhabitants and workers engaged in removing contaminated soil was monitored. As exposures vary over time and between subjects, it should be recognized that sampling as well as analytical variations contribute both to bias and random errors. Also biomonitoring data are a function of demographic, lifestyle and geographic factors. Therefore, stratified sampling designs are of the utmost importance. Half-lives play an important role. For short half-lives below 10 h, no decision can be made on long-term exposure if only one urine sample has been taken. For arsenic, cobalt, chromium and nickel in urine measured at the end of a workweek (t1/2: 20-100 h), 2-3 samples should be taken to monitor a single worker, and the results should be interpreted from the average of the results. For groups of workers, it is recommended that results from at least 5-10 workers be used to obtain a useful group mean value. In general, pharmacokinetics modelling contributes to information on sampling time and sampling size. Intake of cobalt in mineral tablets containing soluble cobalt compounds was a factor with a large influence on blood and urinary levels. Age and gender influence the blood and urine concentrations of arsenic, cadmium, cobalt and lead, e.g. B-Pb in females is 20-30% lower than B-Pb in males.(ABSTRACT TRUNCATED AT 400 WORDS)

Estimation of reference values for urinary 1-hydroxypyrene and alpha-naphthol in Danish workers

In order to assess environmentally and occupationally related exposures to PAH compounds it is essential to have reference or normal values in human body fluids. The establishment of reliable reference intervals is an absolute pre-requisite in determining relationships between internal PAH exposure in humans and health effects in occupationally exposed workers. In this context the estimation of the biological level of PAH metabolites in urine from reference populations has become increasingly important in the field of environmental and occupational toxicology. The present study describes the calculation of tentative reference values for urinary 1-hydroxypyrene on the basis of two reference populations and for urinary alpha-naphthol on the basis of one reference population in accordance with IFCC recommendations. The study subjects were 115 healthy male workers occupationally exposed to PAH at low levels and 121 reference subjects non-occupationally exposed to PAH. Tentative reference values for urinary 1-hydroxypyrene were estimated. In addition, 236 healthy male workers were used to estimate tentative reference values for urinary alpha-naphthol. The reference populations were described by distribution free one-sided tolerance intervals. The 95% one-sided tolerance limit calculated for 1-hydroxypyrene in urine was 0.053 mumol/mol creatinine for non-occupationally exposed individuals and 0.169 mumol/mol creatinine for low level PAH exposed workers, with the coverage interval (95 +/- 4.5) percent at a probability of 0.95. Thus, the probability was 0.975 that the tolerance interval included at least 90.5% of the distribution. In addition, the probability was 0.025 that the tolerance interval included > 99.5% of the population. The tolerance interval for alpha-naphthol in urine was 5.665 mumol/mol creatinine with the coverage interval (95 +/- 4.5) percent at a probability of 0.95.

Assessment of long-term styrene exposure: a comparative study of a logbook method and biological monitoring

In a recent joint European research project "Biomonitoring of human populations exposed to genotoxic environmental chemicals: biomonitoring of styrene exposed individuals", a logbook method for assessment of long-term styrene exposure was applied in two Danish factories manufacturing glass fibre-reinforced polyester. The method was based on work process identification, assignment of work process concentrations and logbook keeping. Measures of exposure calculated by this method were compared with results from simultaneous measurements of styrene in blood and the metabolites mandelic acid and phenylglyoxylic acid in urine. Correlations were comparable with those obtained by use of personal samplers as published in the literature. Styrene in blood, however, only correlated with logbook concentrations at the time of sampling. Exposures were moderate to low. Mean personal 8-h time-weighted average concentration (8hTWAC) was 76 mg/m3 styrene (SD 54 mg/m3, range 2-230 mg/m3). The Danish 8hTWAC threshold limit value for styrene in air, 105 mg/m3 (25 ppm), was exceeded on 17% of personal days. The summed urinary metabolites, mandelic acid and phenylglyoxylic acid, had a mean personal value of 138 mg/g creatinine (SD 84 mg/g creatinine) on the day of sampling. Blood styrene mean value was 129 micrograms/l (SD 74 micrograms/l, range 66-358 micrograms/l). It is concluded that the logbook method offers a technique for testing whether measurements are performed on representative days and may be recommended as a tool supplementary to biological monitoring in the assessment of long-term exposure.

A 1982-1992 surveillance programme on Danish pottery painters. Biological levels and health effects following exposure to soluble or insoluble cobalt compounds in cobalt blue dyes

This paper provides a short overview of cobalt-related diseases with particular reference to the potential carcinogenicity of cobalt compounds, and a review of a 10-year surveillance programme on plate painters exposed to cobalt in two Danish porcelain factories. Clinical experience and epidemiological studies have demonstrated that cobalt exposure may lead to severely impaired lung function, i.e. hard metal lung disease and occupational cobalt-related asthma, contact dermatitis and cardiovascular effects. However, the evidence for the carcinogenicity of cobalt and cobalt compounds is considered inadequate (IARC, 1991). Most frequently, exposure to cobalt occurs simultaneously with exposure to other elements known to pose a health risk, (e.g. nickel, arsenic, chromium, tungsten). The importance of cobalt as sole causal agent in hard metal lung diseases, cardiomyopathy and cancer are still a matter of controversy. In the two Danish porcelain factories, cobalt blue underglaze dyes have been used since 1888. In contrast to the exposure experience of hard metal factories, the exposure of plate painters occurs with only low trace levels of other potentially harmful compounds such as the carcinogenic metals nickel, arsenic and chromium. Consequently, the nearly-pure cobalt exposure makes the plate painters an attractive group for studies on the health effects of cobalt. During the period 1982-1992 the surveillance programme showed a profound reduction in the urine level of cobalt (Co-U) from 100-fold to 10-fold above the median level of the unexposed control subjects. In the same period, the airborne cobalt exposure declined from 1356 nmol/m3 to 454 nmol/m3, the Danish occupational exposure limit being 845 nmol/m3. In 1982, when the cobalt exposure was above the occupational exposure limit, the plate painters showed a chronic impaired lung function. The obstructive effects may be similar to some of the effects observed in hard metal workers. In 1988, a study on the effect of cobalt exposure at low levels revealed no inhibitory effects on thyroid function, but the ratio between T4 and T3 increased, indicating that low cobalt exposure may have an impact on the metabolism of thyroid hormones. Parallel studies were conducted on the metabolism and excretion of cobalt. The gastrointestinal uptake of soluble CoCl was considerably higher than the uptake of insoluble cobalt(II) oxide. In addition, it was demonstrated that ingestion of controlled amounts of the soluble cobalt compound resulted in significantly higher concentrations of cobalt in urine and blood (Co-B) from females compared with males (P < 0.01). Future studies will involve epidemiology and genotoxicity to evaluate the previous and present cancer risk, and detailed process-related exposure assessment studies to select the methods most reliable for surveillance of low-dose cobalt exposure.

Correlation between work process-related exposure to polycyclic aromatic hydrocarbons and urinary levels of alpha-naphthol, beta-naphthylamine and 1-hydroxypyrene in iron foundry workers

In two Danish iron foundries the concentration of polycyclic aromatic hydrocarbons (PAH) in 24 personal air samples of workers employed in selected processes, i.e. melters, melted iron transporters, casters, machine molders, hand molders, shake-out workers and finishing workers, were measured and correlated to levels of 1-hydroxypyrene, alpha-naphthol and beta-naphthylamine in the urine of exposed workers. The highest total airborne PAH concentrations (sum of 15 selected PAH compounds: 9.6-11.2 micrograms/m3) were associated with casting, machine molding, and shake-out. The highest concentrations of the sum of six selected airborne carcinogenic PAH compounds were found for melting, casting and machine and hand molding. As seen in other working environments involving low-level PAH exposure, the content of naphthalene was high, in general exceeding 85% of the total content of PAH compounds. The present study demonstrates that 1-hydroxypyrene is a useful and direct biomarker of low-dose occupational exposure to PAH compounds. Molding and casting had the highest pyrene levels in iron foundries. Furthermore, the data shows that levels of beta-naphthylamine in urine are significantly elevated in iron foundry workers. Hand molders, finishing workers and truck drivers tended to have the highest levels. Concerning alpha-naphthol the highest concentrations were measured in urine from casters and shake-out workers. With regard to epidemiologic studies demonstrating that molders and casters have a higher risk of lung cancer, the present study suggests that the elevated risk may be due to exposure to carcinogenic PAH compounds in iron foundries, particularly in some high-risk work processes, e.g. casting and molding. In addition, the present study suggests that biological monitoring of 1-hydroxypyrene and beta-naphthylamine may be used to estimate the individual exposure, which seems to be correlated with exposure during individual work processes.