A short-term cross-over study on oral administration of soluble and insoluble cobalt compounds: sex differences in biological levels

Exploring the potential function of trace elements in human health: a therapeutic perspective

A trace element, known as a minor element, is a chemical element whose concentration is very low. They are divided into essential and non-essential classes. Numerous physiological and metabolic processes in both plants and animals require essential trace elements. These essential trace elements are so directly related to the metabolic and physiologic processes of the organism that either their excess or deficiency can result in severe bodily malfunction or, in the worst situations, death. Elements can be found in nature in various forms and are essential for the body to carry out its varied functions. Trace elements are crucial for biological, chemical, and molecular cell activity. Nutritional deficits can lead to weakened immunity, increased susceptibility to oral and systemic infections, delayed physical and mental development, and lower productivity. Trace element enzymes are involved in many biological and chemical processes. These compounds act as co-factors for a number of enzymes and serve as centers for stabilizing the structures of proteins and enzymes, allowing them to mediate crucial biological processes. Some trace elements control vital biological processes by attaching to molecules on the cell membrane's receptor site or altering the structure of the membrane to prevent specific molecules from entering the cell. Some trace elements are engaged in redox reactions. Trace elements have two purposes. They are required for the regular stability of cellular structures, but when lacking, they might activate alternate routes and induce disorders. Therefore, thoroughly understanding these trace elements is essential for maintaining optimal health and preventing disease.

Considerations for Applying Route-to-Route Extrapolation to Assess the Safety of Oral Exposure to Substances

The safety evaluation of oral exposure to substances, such as food ingredients, additives, and their constituents, relies primarily on a careful evaluation and analysis of data from oral toxicity studies. When relevant oral toxicity studies are unavailable or may have significant data gaps that make them inadequate for use in safety evaluations, data from non-oral toxicity studies in animals, such as studies on inhalation, dermal exposure, etc., might be used in support of or in place of oral toxicity studies through route-to-route (R-t-R) extrapolation. R-t-R extrapolation is applied on a case-by-case basis as it requires attention to and comparison of substance-specific toxicokinetic (TK) and toxicodynamic (TD) data for oral and non-oral exposure routes. This article provides a commentary on the utility of R-t-R extrapolation to assess the safety of oral exposure to substances, with an emphasis on the relevance of TK and systemic toxicity data.

Dermal and inhalable cobalt exposure-Uptake of cobalt for workers at Swedish hard metal plants

Purpose

Cobalt exposure is known to cause adverse effects on health. A major use of cobalt is in the manufacture of hard metal. Exposure can lead to asthma, hard metal lung disease, contact allergy and increased risk of cancer. Cobalt is mainly absorbed from the pulmonary tract, however penetration through skin may occur. The relationships between exposure to inhalable cobalt in air and on skin and the uptake in blood and urine will be investigated, as well as the association between dermal symptoms and dermal exposure.

Methods

Cobalt exposure in 71 workers in hard metal production facilities was measured as inhalable cobalt in the breathing zone and cobalt found on skin with acid wash. Uptake of cobalt was determined with concentrations in blood and urine. Correlations between exposure and uptake were analysed.

Results

Inhalable cobalt in air and cobalt in blood and urine showed rank correlations with coefficients 0.40 and 0.25. Cobalt on skin and uptake in blood and urine presented correlation coefficients of 0.36 and 0.17. Multiple linear regression of cobalt in air and on skin with cobalt in blood showed regression coefficients with cobalt in blood (β = 203 p < 0.0010, and β = 0.010, p = 0.0040) and with cobalt in urine (β = 5779, p = 0.0010, and β = 0.10, p = 0.60).

Conclusions

Our data presents statistically significant correlations between exposure to cobalt in air with uptake of cobalt in blood and urine. Cobalt on skin was statistically significant with cobalt in blood but not with urine.

Cobalt-containing dust exposures: Prediction of whole blood and tissue concentrations using a biokinetic model

Biokinetic models estimating cobalt (Co) tissue burden can help assess the potential for systemic effects. Such models, however, have not been used to estimate remote tissue concentrations associated with inhalation exposure to Co-containing dust in general environments, work spaces, or animal toxicity tests. We have therefore updated a Co biokinetic model previously developed for oral dosing to include the inhalation pathway by incorporating the International Commission on Radiological Protection (ICRP) Human Respiratory Tract Model. Further, data from animal studies allowed for characterization of testes Co tissue concentration supplementing previous predictions for the liver, heart and blood. Reasonable agreement (within a factor of two) was found between modeled and measured blood, liver, testes and tissue concentrations when animal doses were modeled using human equivalent concentrations to account for species differences in regional lung deposition. We applied the updated model to occupational inhalation exposure scenarios, and found that upper-bound plausible human systemic body burden associated with Co ingestion is much higher than the burden associated with Co inhalation. Chronic ingestion of Co at a previously proposed oral reference dose (RfD) of 0.03 mg/kg-day resulted in predicted tissue levels of 22-54 μg/L (blood), 0.05-0.1 μg/g (heart), 0.01-0.02 μg/g (testes), and 0.2-0.5 μg/g (liver), which were at least 5-fold more than the systemic burden associated with various Co inhalation occupational exposure limits (OELs) of 0.1 mg/m³ or less (for 8 h/d and 5 d/w). Overall, our analysis indicated that Co-metal or dust induced systemic health effects, including myocardial damage, are unlikely for the inhalation pathway when personal exposures levels are below concentrations associated with local respiratory effects such as pulmonary fibrosis.

Relationship between Selected Trace Elements and Hematological Parameters among Japanese Community Dwellers

This study aimed (1) to assess serum trace elements concentrations and hematological parameters, (2) to evaluate the sex differences in the associations between serum trace elements levels and hematological parameters, and (3) to identify the associations between serum trace elements concentrations and risk of anemia among Japanese community dwellers. This is a community-based cross-sectional study that utilized the data of the 2014 Iwaki Health Promotion Project. Participants were 1176 community dwellers (>18 years) residing in the Iwaki District, Aomori Prefecture, Japan. We assessed the data of serum trace elements concentrations of cadmium (Cd), cobalt (Co), copper (Cu), selenium (Se), zinc (Zn), and iron (Fe) as well as the hematological parameters of red blood cells (RBC) counts, hemoglobin, packed cells volume (PCV), mean corpuscular volume (MCV), and mean corpuscular hemoglobin (MCH). Serum concentrations of Zn (871.5 μg/L vs. 900.1 μg/L) and Fe (946.8 μg/L vs. 1096.1 μg/L) were significantly lower in females than in males, while serum concentrations of Co (0.4 μg/L vs. 0.3 μg/L) and Cu (1062.4 μg/L vs. 965.3 μg/L) were significantly higher in females. By multivariate linear regression, serum Se concentration was significantly, positively associated with PCV (β = 1.04; 95% confidence interval (CI): 0.17, 1.92; p = 0.016) among the study participants. Serum Zn also had positive associations with hemoglobin (β = 0.42; 95% CI: 0.07, 0.77; p = 0.020), PCV (β = 1.79; 95% CI: 0.78, 2.81; p < 0.001), and RBCs count (β = 15.56; 95% CI: 7.31, 31.69; p = 0.002). On the other hand, serum Co concentration was negatively associated with the hematological parameters, particularly in females. Moreover, serum Zn concentration had a decreased risk of anemia (lowest vs. highest quartiles: odds ratio (OR) = 0.42; 95% CI: 0.23, 0.76; p = 0.005) while higher Co concentrations had an increased risk of anemia (lowest vs. highest quartiles: OR = 1.95; 95% CI: 1.04, 3.67; p = 0.037). However, no significant association was found between serum Cu level and hematological parameters. There were substantial sex differences in serum trace elements, implying that trace elements metabolism differed between males and females. Zn can play a protective role in the development of anemia. Surprisingly, increased Co concentration increased the risk of anemia among our study population, which called for further studies to confirm and to consider for speciation analysis.

The Cytotoxicity and Genotoxicity of Particulate and Soluble Cobalt in Human Urothelial Cells

Cobalt use is increasing particularly due to its use as one of the primary metals in cobalt-chromium-molybdenum (CoCrMo) metal-on-metal prosthetics. CoCrMo is a high-strength, wear-resistant alloy with reduced risk for prosthetic loosening and device fracture. More than 500,000 people receive hip implants each year in the USA which puts them at potential risk for exposure to metal ions and particles released by the prosthetic implants. Data show cobalt ions released from prosthetics reach the bloodstream and accumulate in the bladder. As patients with failed hip implants show increased urinary and blood cobalt levels, no studies have considered the effects of cobalt on human urothelial cells. Accordingly, we investigated the cytotoxic and genotoxic effects of particulate and soluble cobalt in urothelial cells. Exposure to both particulate and soluble cobalt resulted in a concentration-dependent increase in cytotoxicity, genotoxicity, and intracellular cobalt ions. Based on intracellular cobalt ion levels, we found, when compared to particulate cobalt, soluble cobalt was more cytotoxic, but induced similar levels of genotoxicity. Interestingly, at similar intracellular cobalt ion concentrations, soluble cobalt induced cell cycle arrest indicated by a lack of metaphases not observed after particulate cobalt treatment. These data indicate that cobalt compounds are cytotoxic and genotoxic to human urothelial cells and solubility may play a key role in cobalt-induced toxicity.

Cobalt toxicity in humans-A review of the potential sources and systemic health effects

Cobalt (Co) and its compounds are widely distributed in nature and are part of numerous anthropogenic activities. Although cobalt has a biologically necessary role as metal constituent of vitamin B₁₂, excessive exposure has been shown to induce various adverse health effects. This review provides an extended overview of the possible Co sources and related intake routes, the detection and quantification methods for Co intake and the interpretation thereof, and the reported health effects. The Co sources were allocated to four exposure settings: occupational, environmental, dietary and medical exposure. Oral intake of Co supplements and internal exposure through metal-on-metal (MoM) hip implants deliver the highest systemic Co concentrations. The systemic health effects are characterized by a complex clinical syndrome, mainly including neurological (e.g. hearing and visual impairment), cardiovascular and endocrine deficits. Recently, a biokinetic model has been proposed to characterize the dose-response relationship and effects of chronic exposure. According to the model, health effects are unlikely to occur at blood Co concentrations under 300μg/l (100μg/l respecting a safety factor of 3) in healthy individuals, hematological and endocrine dysfunctions are the primary health endpoints, and chronic exposure to acceptable doses is not expected to pose considerable health hazards. However, toxic reactions at lower doses have been described in several cases of malfunctioning MoM hip implants, which may be explained by certain underlying pathologies that increase the individual susceptibility for Co-induced systemic toxicity. This may be associated with a decrease in Co bound to serum proteins and an increase in free ionic Co²⁺. As the latter is believed to be the primary toxic form, monitoring of the free fraction of Co²⁺ might be advisable for future risk assessment. Furthermore, future research should focus on longitudinal studies in the clinical setting of MoM hip implant patients to further elucidate the dose-response discrepancies.

Body burdens, sources and interrelations of selected toxic and essential elements among the nine Cree First Nations of Eeyou Istchee, James Bay region of northern Quebec, Canada

BACKGROUND

this article constitutes a report on the comprehensive Nituuchischaayihtitaau Aschii multi-community environment-and-health study conducted among the Cree peoples (Eeyouch) of northern Quebec, Canada.

OBJECTIVES

to interpret observed concentrations of a suite of chemical elements in a multi-media biological monitoring study in terms of sources and predictors.

METHODS

the concentrations of 5 essential and 6 toxic chemical elements were measured in whole blood, and/or in urine or hair by ICP-MS. Concentrations of essential elements are compared to those considered normal (i.e., required for good health) and, when toxic, deemed acceptable at specified concentrations in public health guidelines. Their dependence on age, sex, the specific community lived-in and diet were explored employing multivariate analysis of variance (MANOVA) involving new variables generated by principle component analysis (PCA) and correspondence analysis (CA).

RESULTS

the 5 most prominent PCA axes explained 67.7% of the variation, compared to 93.0% by 6 main CA factors. Concentrations of the essential elements in whole blood (WB) and iodine(i) and arsenic (As) in urine were comparable to those reported in the recent Canadian Health Measures survey and are assigned to dietary sources. By contrast, WB cadmium (Cd) was elevated even when smoking was considered. Mercury (Hg) concentrations in WB and hair were also higher in adults, although comparable to those observed for other indigenous populations living at northern latitudes. Fish consumption was identified as the prominent source. Of the 5 coastal communities, all but one had lower Hg exposures than the four inland communities, presumably reflecting the type of fish consumed. Use of firearms and smoking were correlated with WB-lead (Pb). The concentrations of both Hg and Pb increased with age and were higher in men, while WB-Cd and smoking prevalence were higher in women when considering all communities. Hg and Pb were low in children and women of reproductive age, with few exceedances of health guidelines. Although individuals with T2D had somewhat lower WB-Cd, there is some indication that Cd may potentiate renal dysfunction in this subgroup. Plots of selected CA axes grouped those elements expected to be in a normal diet and distinguished them from those with well-known unique sources (especially Hg and As in hair; and Hg, Pb and Cd in WB).

CONCLUSIONS

the use of multiple biological media in conjunction with the complementary PCA and CA approaches for constructing composite variables allowed a more detailed understanding of both the sources of the essential and toxic elements in body fluids and the dependencies of their observed concentrations on age, sex, community and diet.

Nutritional Aspects of Essential Trace Elements in Oral Health and Disease: An Extensive Review

Human body requires certain essential elements in small quantities and their absence or excess may result in severe malfunctioning of the body and even death in extreme cases because these essential trace elements directly influence the metabolic and physiologic processes of the organism. Rapid urbanization and economic development have resulted in drastic changes in diets with developing preference towards refined diet and nutritionally deprived junk food. Poor nutrition can lead to reduced immunity, augmented vulnerability to various oral and systemic diseases, impaired physical and mental growth, and reduced efficiency. Diet and nutrition affect oral health in a variety of ways with influence on craniofacial development and growth and maintenance of dental and oral soft tissues. Oral potentially malignant disorders (OPMD) are treated with antioxidants containing essential trace elements like selenium but even increased dietary intake of trace elements like copper could lead to oral submucous fibrosis. The deficiency or excess of other trace elements like iodine, iron, zinc, and so forth has a profound effect on the body and such conditions are often diagnosed through their early oral manifestations. This review appraises the biological functions of significant trace elements and their role in preservation of oral health and progression of various oral diseases.

Hair concentration of essential trace elements in adult non-exposed Russian population

Appropriate reference values of hair trace element content are required for correct interpretation of biomonitoring data. The primary objective of the current study was to estimate the reference values of selected essential trace elements in hair of adult Russian population. Involved in current investigation were 7256 occupationally non-exposed adults aged from 20 to 60 years and living in the European part of Russia. Occipital hair essential metal and metalloid (Co, Cr, Cu, Fe, Mn, Se, V, Zn) content was estimated using inductively coupled plasma mass spectrometry. The reference ranges were calculated in accordance with the International Union of Pure and Applied Chemistry (IUPAC) recommendations. Women were characterized by 55, 18, 58, and 7% higher values of hair Co, Cu, Mn, and Zn content as compared to the values observed in men. At the same time, hair Cr, Fe, Se, and V concentration in men significantly exceeded the respective female values by 65, 13, 20, and 56%. Consequently, the reference ranges of essential hair trace elements content should be separately calculated for both men and women. The obtained reference ranges for hair Co, Cr, Cu, Fe, Mn, Se, V, and Zn in men were 0.11-0.67, 0.007-0.045, 10.4-22.6, 11.1-40.5, 0.24-1.05, 0.089-0.480, 0.014-0.083, and 125.7-262.8 μg/g, respectively. The respective values estimated for women were 0.06-0.40, 0.011-0.085, 12.1-44.5, 8.9-25.6, 0.32-2.05, 0.094-0.504, 0.010-0.056, and 140.0-315.1 μg/g. The reference ranges for hair Co (0.07-0.50), Cr (0.009-0.073), Cu (11.8-29.2), Fe (9.6-31.5), Mn (0.29-1.76), Se (0.093-0.482), V (0.011-0.069), and Zn (134.7-301.9) content (μg/g) in the general cohort were also calculated.

Interdependence between urinary cobalt concentrations and hemoglobin levels in pregnant women

Cobalt is an essential trace element but may cause toxic effects upon occupational or environmental exposure. Women accumulate more cobalt than men at similar exposure levels which may be related to higher metabolic iron loss. During pregnancy these losses are much stronger but their influence on cobalt intake has not been studied. We have studied the associations between changes in hemoglobin and cobalt urinary excretion during pregnancy. 391 pairs of urine and blood samples from pregnant women were collected during the 12th and 32nd weeks of pregnancy and were analyzed for cobalt and hemoglobin. Mean concentrations of urinary cobalt were 0.73 and 1.6 µg/g creatinine during the first and third trimesters, respectively (p<0.001). 84% of pregnant women had higher levels of cobalt in the third than in the first trimester. Cobalt concentrations were negatively associated to hemoglobin levels in the third trimester (p<0.05). Women with higher iron decreases between both trimesters had significant cobalt increases between these two periods. This correspondence involved a statistically significant difference in third trimester mean cobalt concentrations of anemic and non-anemic women, 1.8 and 1.5 µg/g creatinine, respectively (p<0.05). No significant differences between these two groups were found during the first trimester. These results were used to construct generalized additive models both in normal and anemic women. The strong association between the changes of both iron status and cobalt urine levels found in pregnant women may be related to higher intestinal absorption of cobalt at iron depletion such as in the last pregnancy period when iron body demands are high. Possible toxicity effects of these cobalt increases along pregnancy should be considered in cases of populations occupationally or environmentally exposed to this metal.

Intolerability of cobalt salt as erythropoietic agent

Unfair athletes seek ways to stimulate erythropoiesis, because the mass of haemoglobin is a critical factor in aerobic sports. Here, the potential misuse of cobalt deserves special attention. Cobalt ions (Co(2+) ) stabilize the hypoxia-inducible transcription factors (HIFs) that increase the expression of the erythropoietin (Epo) gene. Co(2+) is orally active, easy to obtain, and inexpensive. However, its intake can bear risks to health. To elaborate this issue, a review of the pertinent literature was retrieved by a search with the keywords 'anaemia', 'cobalt', 'cobalt chloride', 'erythropoiesis', 'erythropoietin', 'Epo', 'side-effects' and 'treatment', amongst others. In earlier years, cobalt chloride was administered at daily doses of 25 to 300 mg for use as an anti-anaemic agent. Co(2+) therapy proved effective in stimulating erythropoiesis in both non-renal and renal anaemia, yet there were also serious medical adverse effects. The intake of inorganic cobalt can cause severe organ damage, concerning primarily the gastrointestinal tract, the thyroid, the heart and the sensory systems. These insights should keep athletes off taking Co(2+) to stimulate erythropoiesis.

Evaluation of metal ion release from Ti6Al4V and Co-Cr-Mo casting alloys: in vivo and in vitro study

PURPOSE

The aim of this study was to evaluate the amount of ions released from Ti6Al4V and Co-Cr-Mo alloys both in vivo and in vitro.

MATERIALS AND METHODS

Twenty-one discs of each alloy were constructed and divided into seven groups. Three specimens from each group were immersed in a buffered saline solution over a period of 1, 3, 5, 7, 14, 21, and 28 days. Twenty-eight participants were also included in the study, where the study group consisted of 14 mandibular partially edentulous patients, and the control group consisted of 14 volunteers. The study group was further divided into two equal groups: the first group received removable partial dentures (RPDs) constructed from Co-Cr-Mo alloy, while the second group received RPDs constructed from Ti6Al4V alloy. Saliva samples were collected from each participant over the same study period. The conditioning media and saliva samples were analyzed using a spectrophotometer. One-way ANOVA and Tukey tests were used for statistical analysis (p < 0.05).

RESULTS

The concentrations of metal ions released from the studied alloys were significantly higher in the in vitro than in the in vivo study group during the follow-up periods. A statistically significant increase in ion concentrations of the different elements for both alloys was found with time (p < 0.05).

CONCLUSION

The amounts of released metallic ions from Co-Cr-Mo and Ti6Al4V alloys were higher in the buffered saline solutions than in the studied saliva samples and control groups; however, these amounts were still within the physiological limit of trace elements in the human body.

31-day study of cobalt(II) chloride ingestion in humans: pharmacokinetics and clinical effects

The United Kingdom Expert Group on Vitamins and Minerals concluded that ingesting cobalt (Co)-containing supplements up to 1400 μg Co/d is unlikely to produce adverse health effects. However, the associated blood Co concentrations and safety of Co-containing dietary supplements have not been fully characterized. Thus, blood Co kinetics and a toxicological assessment of hematological and biochemical parameters were evaluated following Co dietary supplementation in 5 male and 5 female volunteers who ingested approximately 1000 μg Co/d (10-19 μg Co/kg-d) as cobalt(II) chloride for a period of 31 d. Supplement intake was not associated with significant overt adverse events, alterations in clinical chemistries including blood counts and indicators of thyroid, cardiac, liver, or kidney functions, or metal sensitization. A non-clinically significant (<5%) increase in hemoglobin, hematocrit, and red blood cell (RBC) counts were observed in males but not females 1 wk after dose termination. Mean Co concentrations in whole blood/serum after 31 d of dosing were approximately two-fold higher in females (33/53 μg/L) than in males (16/21 μg/L). In general, steady-state concentrations of Co were achieved in whole blood and/or red blood cells (RBC) within 14-24 d. Temporal patterns of whole blood and serum Co concentrations indicated metal sequestration in RBC accompanied by slower whole blood clearance compared to serum. Data also indicated that peak whole blood Co concentrations up to 91.4 μg/L were not associated with clinically significant changes in clinical chemistries. In addition, Co blood concentrations and systemic uptake via ingestion were generally higher in females.

Occupational exposure to cobalt: a population toxicokinetic modeling approach validated by field results challenges the biological exposure index for urinary cobalt

This study modeled the urinary toxicokinetics of cobalt exposure based on 507 urine samples from 16 workers, followed up for 1 week, and 108 related atmospheric cobalt measurements to determine an optimal urinary cobalt sampling strategy at work and a corresponding urinary exposure threshold (UET). These data have been used to calibrate a population toxicokinetic model, taking into account both the measurement uncertainty and intra- and interindividual variability. Using the calibrated model, urinary sampling sensitivity and specificity performance in detecting exposure above the 20 microg/m(3) threshold limit value - time-weighted average (TLV-TWA) has been applied to identify an optimal urine sampling time. The UET value is obtained by minimizing misclassification rates in workplace exposures below or above the TLV. Total atmospheric cobalt concentrations are in the 5-144 microg/m(3) range, and total urinary cobalt concentrations are 0.5-88 microg/g creatinine. A two-compartment toxicokinetic model best described urinary elimination. Terminal elimination half-time from the central compartment is 10.0 hr (95% confidence interval [8.3-12.3]). The optimal urinary sampling time has been identified as 3 hr before the end of shift at the end of workweek. If we assume that misclassification errors are of equal cost, the UET associated with the TLV of 20 microg/m(3) is 5 microg/L, which is lower than the ACGIH-recommended biological exposure index of 15 microg/L.

The biokinetics of inorganic cobalt in the human body

This paper reviews information on the biological behavior of inorganic cobalt in humans and laboratory animals and proposes a model of the systemic biokinetics of inorganic cobalt in adult humans. The model was developed as part of an effort to update the models of the International Commission on Radiological Protection (ICRP) for addressing intakes of radionuclides by workers but is also applicable to environmental or medical exposures to inorganic forms of radiocobalt. The model can be used in conjunction with any respiratory, gastrointestinal, or wound model that provides predictions of the time-dependent feed of cobalt to blood. In contrast to the ICRP's current systemic model for cobalt, which is a simple open catenary system, the proposed model is constructed within a physiologically realistic framework that depicts recycling of cobalt between blood and tissues and transfer from blood to excretion pathways. Compared with the ICRP's current model, the proposed model yields similar predictions of whole-body retention but substantially different predictions of the systemic distribution of cobalt as a function of time after uptake to blood.

Trace elements in blood and serum of Swedish adolescents: relation to gender, age, residential area, and socioeconomic status

The influence of gender, age, residential area, and socioeconomic status on the blood and serum levels of 13 trace elements was studied in boys and girls living in two Swedish cities with different socioeconomic and environmental characters. The same groups of adolescents were sampled twice, at ages 15 (n=372) and 17 (n=294) years. All the investigated factors were shown to be of importance. Age was important for most elements; e.g., copper levels in both blood and serum increased in girls, and selenium increased in serum from both genders. Lead decreased approximately 10% in blood from the first to the second sampling, and cadmium increased in blood, however not in nonsmokers. The age factor may also reflect temporal changes in environmental exposure, especially for nonessential elements. Girls had higher levels of cobalt and copper, while lead in blood was higher in boys. Smoking girls had higher copper levels than nonsmoking girls. Residential area influenced all elements. The teenagers with university-educated mothers had higher levels of cadmium in blood than those with only primary school-educated mothers.

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.

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.

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.