Biological monitoring of welders exposed to aluminium

Toxicity and biokinetics following pulmonary exposure to aluminium (aluminum): A review

During the manufacture and use of aluminium (aluminum), inhalation exposure may occur. We reviewed the pulmonary toxicity of this metal including its toxicokinetics. The normal serum/plasma level based on 17 studies was 5.7 ± 7.7 µg Al/L (mean ± SD). The normal urine level based on 15 studies was 7.7 ± 5.3 µg/L. Bodily fluid and tissue levels during occupational exposure are also provided, and the urine level was increased in aluminium welders (43 ± 33 µg/L) based on 7 studies. Some studies demonstrated that aluminium from occupational exposure can remain in the body for years. Excretion pathways include urine and faeces. Toxicity studies were mostly on aluminium flakes, aluminium oxide and aluminium chlorohydrate as well as on mixed exposure, e.g. in aluminium smelters. Endpoints affected by pulmonary aluminium exposure include body weight, lung function, lung fibrosis, pulmonary inflammation and neurotoxicity. In men exposed to aluminium oxide particles (3.2 µm) for two hours, lowest observed adverse effect concentration (LOAEC) was 4 mg Al2O3/m3 (= 2.1 mg Al/m3), based on increased neutrophils in sputum. With the note that a similar but not statistically significant increase was seen during control exposure. In animal studies LOAECs start at 0.3 mg Al/m3. In intratracheal instillation studies, all done with aluminium oxide and mainly nanomaterials, lowest observed adverse effect levels (LOAELs) started at 1.3 mg Al/kg body weight (bw) (except one study with a LOAEL of ∼0.1 mg Al/kg bw). The collected data provide information regarding hazard identification and characterisation of pulmonary exposure to aluminium.

Biomonitoring of exposure to multiple metal components in urine, hair and nails of apprentice welders performing shielded metal arc welding (SMAW)

Welding fumes are associated with various diseases. Increased air levels of metals were reported during welding. However, few multielement biomonitoring studies were conducted to assess the actual dose of metal components absorbed in apprentice welders in a learning environment. This research aimed to establish the nature and level of exposure to welding fumes and their metallic components in apprentice welders performing 'Shielded Metal Arc Welding' (SMAW), based on multi-element and multi-matrix analyses. A total of 86 apprentice welders were recruited in three different schools in Montreal, Québec, Canada. Twenty-one elements were measured in urine, hair, fingernail, and toenail samples collected at the beginning of the program and at the end of SMAW practical training. Concentrations of welding fumes and 12 metals were also determined in personal respirable air samples collected over a typical workday in a subgroup of 19 apprentices. Levels of manganese (Mn), iron (Fe) and nickel (Ni) in urine and Mn in hair were higher in samples taken at the end of the SMAW module compared to the beginning of training, while there was no significant difference for the other elements or for nail concentrations. Geometric mean concentrations [5th-95th percentiles] reached 0.31 [0.032-2.84], 9.4 [3.1-51] and 0.87 [0.35-3.1] μg/g creat. in post-shift urine, respectively, for Mn, Fe and Ni, and 0.37 [0.46-6.4] μg Mn/g hair at the end of SWAW. Median concentrations [5th-95th percentiles] were 29 [4.6-1200], 120 [27-3100] and 0.31 [ Collapse

Key Words

• Biomonitoring
• Metalloids
• Metals
• Occupational exposure
• Shielded metal arc welding
• Welding fume exposure

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MESH Headings

• Humans
• Nails/chemistry
• Air Pollutants, Occupational/analysis
• Biological Monitoring
• Welding
• Metal Workers
• Metals/analysis
• Occupational Exposure/analysis
• Manganese/analysis
• Nickel
• Gases

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Affiliation(s)

Jairo Buitrago Cortes Department of Environmental and Occupational Health, Chair in Toxicological Risk Assessment and Management, and Public Health Research Center (CReSP), University of Montreal, Roger-Gaudry Building, U436, P.O. Box 6128, Main Station, Montreal, Quebec, H3C 3J7, Canada
Philippe Sarazin Chemical and Biological Hazards Prevention, Institut de recherche Robert-Sauvé en santé et en sécurité du travail, 505 Boulevard de Maisonneuve O, Montréal, Québec, H3A 3C2, Canada
Denis Dieme Department of Environmental and Occupational Health, Chair in Toxicological Risk Assessment and Management, and Public Health Research Center (CReSP), University of Montreal, Roger-Gaudry Building, U436, P.O. Box 6128, Main Station, Montreal, Quebec, H3C 3J7, Canada
Jonathan Côté Department of Environmental and Occupational Health, Chair in Toxicological Risk Assessment and Management, and Public Health Research Center (CReSP), University of Montreal, Roger-Gaudry Building, U436, P.O. Box 6128, Main Station, Montreal, Quebec, H3C 3J7, Canada
Capucine Ouellet Chemical and Biological Hazards Prevention, Institut de recherche Robert-Sauvé en santé et en sécurité du travail, 505 Boulevard de Maisonneuve O, Montréal, Québec, H3A 3C2, Canada
Naïma El Majidi Department of Environmental and Occupational Health, Chair in Toxicological Risk Assessment and Management, and Public Health Research Center (CReSP), University of Montreal, Roger-Gaudry Building, U436, P.O. Box 6128, Main Station, Montreal, Quebec, H3C 3J7, Canada
Michèle Bouchard Department of Environmental and Occupational Health, Chair in Toxicological Risk Assessment and Management, and Public Health Research Center (CReSP), University of Montreal, Roger-Gaudry Building, U436, P.O. Box 6128, Main Station, Montreal, Quebec, H3C 3J7, Canada.

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Al3+-Responsive Ratiometric Fluorescent Sensor for Creatinine Detection: Thioflavin-T and Sulfated-β-Cyclodextrin Synergy

Kidney disorders are a rising global health issue, necessitating early diagnosis for effective treatment. Creatinine, a metabolic waste product from muscles, serves as an ideal biomarker for kidney damage. The existing optical methods for creatinine detection often involve labor-intensive synthesis processes and present challenges with the aqueous solubility and sensitivity to experimental variations. In this study, we introduce a straightforward fluorescence "turn-on" ratiometric sensor system for creatinine detection in aqueous media with a limit of detection of 0.5 μM. The sensor is based on sulfated-β-cyclodextrin (SCD)-templated H-aggregate of a commercially available, ultrafast rotor dye thioflavin-T (ThT). The Al3+ ion-induced dissociation of ThT-SCD aggregates, followed by reassociation upon creatinine addition, generates a detectable signal. The modulation of monomer/aggregate equilibrium due to the disassembly/reassembly of the ThT-SCD system under Al3+/creatinine influence serves as the optimal strategy for ratiometric creatinine detection in aqueous media. Our sensor framework offers several advantages: utilization of the readily available dye ThT, which eliminates the need for a laborious synthesis of custom fluorescent probes; ratiometric sensing, which improves quantitative analysis accuracy; and compatibility with complex aqueous media. The sensor's practical utility has been successfully demonstrated in artificial urine samples. In summary, our sensor system represents a significant advancement in the rapid, selective, and sensitive detection of the clinically crucial bioanalyte creatinine, offering potential benefits for the early diagnosis and management of kidney disorders.

Occupational exposure during metal additive manufacturing: A case study of laser powder bed fusion of aluminum alloy

Occupational exposure during metal additive manufacturing (Laser Powder Bed Fusion) using an aluminum alloy (AlSi10Mg) was assessed. Background aerosols before manufacturing, powder sieving, machine loading, manufacturing, machine unloading, powder unpacking, and machine cleaning were analyzed. Measurements were taken simultaneously at the source, in the near field, and on the operator during five manufacturing cycles. Aerosol measurement devices and physico-chemical techniques were used to determine the particle number or mass concentration (DiSCmini, core particle counter and sampling cassette), particle size distribution (NanoScan, optical particle detector and impactor), and the shape/size and chemical compositions of the inhalable particles (laser diffraction, inductively coupled plasma spectroscopy, scanning electron microscopy, energy dispersive X-ray microanalysis, and Brunauer-Emmett-Teller Method). The laser powder-bed fusion machine emitted in the additive manufacturing room an inhalable fraction of 2.37 ± 0.35 mg/m3, with an aerosol number concentration ranging from 2 × 104 to 105 #/cm3 and a mass mean aerodynamic diameter of 318 nm. A relatively low concentration level was observed in the near field of the machine with an aerosol number concentration of ∼104 #/cm3. A higher concentration level on the operator was attained during the unpacking and cleaning steps, showing an inhalable fraction of 1.73 ± 0.30 mg/m3. Al and Mg nanoparticles were aerosolized at the source (inside the laser powder-bed fusion machine) with a particle size distribution of 153 nm for Al and 117 nm for Mg and an aerosol number concentration reaching ten times that of the background aerosol level. The number or mass concentration of particles in the room atmosphere was increased to double that of the background aerosol level at specific workstations during manufacturing. Metal additive manufacturing is a source of potential occupational exposure to airborne metal nanoparticles. Particle-counting instruments showed high numbers of nanoparticles and some important peaks of particles ranging from 10 nm to 10 µm or larger at specific work tasks in the Additive Manufacturing (AM) environment. A multimetric approach was used to characterize the particle emissions resulting from this type of additive manufacturing.

The REACH registration process: A case study of metallic aluminium, aluminium oxide and aluminium hydroxide

The European Union's REACH Regulation requires determination of potential health and environmental effects of chemicals in commerce. The present case study examines the application of REACH guidance for health hazard assessments of three high production volume (HPV) aluminium (Al) substances: metallic aluminium, aluminium oxide, and aluminium hydroxide. Among the potential adverse health consequences of aluminium exposure, neurotoxicity is one of the most sensitive targets of Al toxicity and the most critical endpoint. This case study illustrates integration of data from multiple lines of evidence into REACH weight of evidence evaluations. This case study then explains how those results support regulatory decisions on classification and labelling. Challenges in the REACH appraisal of Al compounds include speciation, solubility and bioavailability, application of assessment factors, read-across rationale and differences with existing regulatory standards. Lessons learned from the present case study relate to identification and evaluation of toxicologic and epidemiologic data; assessing data relevance and reliability; development of derived no-effect levels (DNELs); addressing data gaps and preparation of chemical safety reports.

Nanoparticle Exposure and Workplace Measurements During Processes Related to 3D Printing of a Metal Object

Metal 3D printing has many potential uses within prototyping and manufacturing. Selective laser melting (SLM) is a process that uses metal powders in the micrometer range as printing material. The particle release from the entire SLM printing process is not well-studied. While the 3D printing itself often occurs in a sealed chamber, activities related to the process can potentially release harmful metal particles to the indoor working environment through resuspension of the printing powder or via incident nanoparticles generated during printing. The objective of this study was to improve the understanding of particle exposure in work processes associated with 3D printing and potential needs for interventions by a case study conducted in a 3D printing facility. In this setting, direct release and dispersion of particles throughout the workspace from processes related to metal 3D printing was investigated. The release from five activities were studied in detail. The activities included post-printing cleaning, object annealing, and preparation of new base substrate for the next printing was. Three of the five measured activities caused particles number concentrations in the working environment to increase above background levels which were found to be 8·10² cm^-3. Concentrations during chamber emptying and the open powder removal system (PRS) cleaning processes increased to 10⁴ and 5·10³ cm^-3, respectively, whereas grinding activity increased number concentrations to 2.5·10⁵ cm^-3. Size distributions showed that particles were mainly smaller than 200 nm. Respirable mass concentrations were 50.4 μg m^-3, collected on filters. This was corroborated by respirable mass measured with a DustTrak of 58.4 μg m^-3. Respirable mass concentrations were below the occupational exposure limits in Denmark for an 8 h time-weighted average.

Overview of the Relationship Between Aluminum Exposure and Health of Human Being

Aluminum is a type of ubiquitously existing naturally and widely used metal in our world. It is combined with other elements and forms different compounds. In different pH and due to other conditions, it can be released into ions of different valence states. Our century is an "aluminum age"; aluminum is used in many fields of our daily life, such as vaccine adjuvant, antacids, food additives, skin care products, cosmetics, and cooking wares, and may be as elements or contaminants appeared in a lot of foods, including infant formulae, milk products, juice, wine, sea foods, and tea. It also appears in drinking water due to the water treatment process, or naturally coming from weathering rocks and soils, or released from rocks and soils caused by pollution-induced acid rain. Due to good physical and chemical property, aluminum is being tremendously utilized in many industries. In a lot of production and process procedures, aluminum particulates are seriously exposed by workers. Many factors, such as silicon, citrate, iron, calcium, fluoride, etc., can affect absorption of aluminum in human body. Human being ingests aluminum through the respiratory and digestive system and skin. Aluminum can affect our health, especially impair central nervous system. The important damage is cognitive impairment in Al-exposed peoples, Alzheimer's disease and other neurodegenerative disorders have been related with aluminum exposure, and aluminum has been proposed as etiology.

A study of the association between urinary aluminum concentration and pre-clinical findings among aluminum-handling and non-handling workers

BACKGROUND

Aluminum is considered to be a relatively safe metal for humans. However, there are some reports that aluminum can be toxic to humans and animals. In order to estimate the toxicity of aluminum with respect to humans, we measured the aluminum concentration in urine of aluminum-handling and non-handling workers and investigated the relationships between their urinary aluminum concentrations and pre-clinical findings.

METHODS

Twenty-three healthy aluminum-handling workers and 10 healthy non-aluminum-handling workers participated in this study. Their medical examinations, which were otherwise unremarkable, included the collection of urine and blood. Urinary aluminum levels were analyzed using ICP analysis. As pre-clinical tests, we measured KL-6, SP-D, TRCP-5b, IL-6, and IL-8 in blood and δ-ALA and β2-microglobulin in urine. These were considered to be lung, bone, kidney and inflammation markers. Moreover, we measured 8-OHdG in urine as an oxidative DNA damage marker.

RESULTS

The aluminum concentration in urine ranged from 6.9 to 55.1 μg/g cre (median: 20.1 μg/g cre) in the aluminum-handling workers and from 5.6 to 15.6 μg/g cre (median: 8.8 μg/g cre) in the non-aluminum-handling workers, with a significant difference between them. In the pre-clinical findings, there were no significant differences between these two groups except in the case of δ-ALA. However, there were no significant relationships between aluminum concentration and the pre-clinical findings, work years, age or 8-OHdG in the aluminum-handling workers.

CONCLUSIONS

While the excretion of aluminum in urine was elevated in aluminum-handling workers, our findings suggest that low-dose aluminum is not directly harmful to humans, at least when workers' urinary aluminum concentration is below 55 μg/g cre.

Human biomonitoring of aluminium after a single, controlled manual metal arc inert gas welding process of an aluminium-containing worksheet in nonwelders

PURPOSE

Several existing field studies evaluate aluminium welding works but no thoroughly controlled exposure scenario for welding fume has been described yet. This study provides information about the uptake and elimination of aluminium from welding fumes under controlled conditions.

METHODS

In the Aachen Workplace Simulation Laboratory, we are able to generate welding fumes of a defined particle mass concentration. We exposed 12, until then occupationally unexposed participants with aluminium-containing welding fumes of a metal inert gas (MIG) welding process of a total dust mass concentration of 2.5 mg/m(3) for 6 h. Room air filter samples were collected, and the aluminium concentration in air derived. Urine and plasma samples were collected directly before and after the 6-h lasting exposure, as well as after 1 and 7 days. Human biomonitoring methods were used to determine the aluminium content of the samples with high-resolution continuum source atomic absorption spectrometry.

RESULTS

Urinary aluminium concentrations showed significant changes after exposure compared to preexposure levels (mean t(1) (0 h) 13.5 µg/L; mean t(2) (6 h) 23.5 µg/L). Plasma results showed the same pattern but pre-post comparison did not reach significance.

CONCLUSIONS

We were able to detect a significant increase of the internal aluminium burden of a single MIG aluminium welding process in urine, while plasma failed significance. Biphasic elimination kinetic can be observed. The German BAT of 60 µg/g creatinine was not exceeded, and urinary aluminium returned nearly to baseline concentrations after 7 days.

Systematic review of potential health risks posed by pharmaceutical, occupational and consumer exposures to metallic and nanoscale aluminum, aluminum oxides, aluminum hydroxide and its soluble salts

Abstract Aluminum (Al) is a ubiquitous substance encountered both naturally (as the third most abundant element) and intentionally (used in water, foods, pharmaceuticals, and vaccines); it is also present in ambient and occupational airborne particulates. Existing data underscore the importance of Al physical and chemical forms in relation to its uptake, accumulation, and systemic bioavailability. The present review represents a systematic examination of the peer-reviewed literature on the adverse health effects of Al materials published since a previous critical evaluation compiled by Krewski et al. (2007) . Challenges encountered in carrying out the present review reflected the experimental use of different physical and chemical Al forms, different routes of administration, and different target organs in relation to the magnitude, frequency, and duration of exposure. Wide variations in diet can result in Al intakes that are often higher than the World Health Organization provisional tolerable weekly intake (PTWI), which is based on studies with Al citrate. Comparing daily dietary Al exposures on the basis of "total Al"assumes that gastrointestinal bioavailability for all dietary Al forms is equivalent to that for Al citrate, an approach that requires validation. Current occupational exposure limits (OELs) for identical Al substances vary as much as 15-fold. The toxicity of different Al forms depends in large measure on their physical behavior and relative solubility in water. The toxicity of soluble Al forms depends upon the delivered dose of Al(+3) to target tissues. Trivalent Al reacts with water to produce bidentate superoxide coordination spheres [Al(O2)(H2O4)(+2) and Al(H2O)6 (+3)] that after complexation with O2(•-), generate Al superoxides [Al(O2(•))](H2O5)](+2). Semireduced AlO2(•) radicals deplete mitochondrial Fe and promote generation of H2O2, O2 (•-) and OH(•). Thus, it is the Al(+3)-induced formation of oxygen radicals that accounts for the oxidative damage that leads to intrinsic apoptosis. In contrast, the toxicity of the insoluble Al oxides depends primarily on their behavior as particulates. Aluminum has been held responsible for human morbidity and mortality, but there is no consistent and convincing evidence to associate the Al found in food and drinking water at the doses and chemical forms presently consumed by people living in North America and Western Europe with increased risk for Alzheimer's disease (AD). Neither is there clear evidence to show use of Al-containing underarm antiperspirants or cosmetics increases the risk of AD or breast cancer. Metallic Al, its oxides, and common Al salts have not been shown to be either genotoxic or carcinogenic. Aluminum exposures during neonatal and pediatric parenteral nutrition (PN) can impair bone mineralization and delay neurological development. Adverse effects to vaccines with Al adjuvants have occurred; however, recent controlled trials found that the immunologic response to certain vaccines with Al adjuvants was no greater, and in some cases less than, that after identical vaccination without Al adjuvants. The scientific literature on the adverse health effects of Al is extensive. Health risk assessments for Al must take into account individual co-factors (e.g., age, renal function, diet, gastric pH). Conclusions from the current review point to the need for refinement of the PTWI, reduction of Al contamination in PN solutions, justification for routine addition of Al to vaccines, and harmonization of OELs for Al substances.

Unreported cardiac arrhythmias in aluminium worker

Aluminium (Al) is the third most prevalent element, representing approximately 8% of total mineral components in the earth's crust (1). Chronic exposure to Al is mainly encountered at particular work places, for example, in foundries or in the Al powder industry, as an occupational exposure. In case of occupational Al exposure, inhalation is the main route of uptake. Chronic exposure to Al is associated with skeletal, neurological, hematological and lung changes. Studies regarding the Al powder industry showed that long-term inhalative exposure to Al can induce pulmonary fibrosis (2). Although there is only one report about ventricular tachycardia as a cardiac manifestation in occupationally exposed persons (3), in this report, we presented a case that had Mobitz type I second-degree atrioventricular block and nonsustained ventricular tachycardia. To our knowledge, this is the first report in chronic poisoning.

Early effects of aluminum chloride on beta-secretase mRNA expression in a neuronal model of beta-amyloid toxicity

Amyloid beta peptide (Abeta), generated by proteolytic cleavage of the amyloid precursor protein (APP), plays a pivotal role in the pathogenesis of Alzheimer's disease (AD). The key step in the generation of Abeta is cleavage of APP by beta-secretases (beta-site APP-cleaving enzyme 1 (BACE1) and BACE2). There has been suggestion of interaction between aluminum and several AD-associated pathways. However, the underlying mechanisms still remain unclear. Here, we report the effects of aluminum chloride (AlCl(3)) in Abeta-induced toxicity using differentiated neuronal SH-SY5Y cells. The metal significantly enhances Abeta-induced cell death at concentrations ranging from 50 to 300 microM after 24 and 48 h. After 72 and 96 h treatment, cell death is increased already at 10 microM. Early coexposure of cells to 10 microM AlCl(3) and 2 microM Abeta differentially affected beta-secretase mRNA levels as compared to single Abeta treatment after 1 and 3 h. BACE1 levels were slightly reduced after 1 h and significantly increased after 3 h exposure, whereas BACE2 levels were increased at both times considered. Both genes' mRNA levels were downregulated at longer times (6, 12, and 24 h). Although these results indicate that aluminum toxicity is correlated to changes in both BACE1 and BACE2 expression levels, the subsequent common downregulation observed suggests that aluminum involvement in the Abeta cascade is subtle, and other underlying mechanisms might be involved.

Longitudinal study on potential neurotoxic effects of aluminium: I. Assessment of exposure and neurobehavioural performance of Al welders in the train and truck construction industry over 4 years

OBJECTIVES

Previous cross sectional studies on potential neurotoxic effects of long-term aluminium exposures by aluminium welders lack clear interpretable results for methodological reasons. The present longitudinal study examined on the one hand the reliability and representativity of Al-biomonitoring as indicator of individual long-term exposure and on the other hand the long-term changes of neurobehavioural performance in Al welders in relation to Al exposure and neurobehavioural performance changes of a non-exposed control group.

METHODS

The longitudinal study compared repeatedly measured exposure data and neurobehavioural data of 20, initially 44, male Al welders in the train and truck construction industry with data of a control group of similar age on the basis of three investigations over a period of 4 years. The repeated measurements of exposure included total dust in air as well as Al in pre- and post-shift plasma and urine samples. Neurobehavioural methods comprised symptoms, verbal intelligence, logic thinking, psychomotor behaviour, memory, and attention. Computer-aided tests from the Motor Performance Series (MLS) and the European Neurobehavioural Evaluation System (EURO-NES) were used. The characteristics of the biomonitoring data and the relationship to neurobehavioural data were examined with methods of correlation and regression analysis. The courses of neurobehavioural changes were analysed with multivariate covariance-analytical methods (MANCOVA) considering the covariates age, indicators of 'a priori' intelligence differences (education or 'premorbid' intelligence), and alcohol consumption (carbohydrate-deficient transferrin in plasma, CDT).

RESULTS

The mean total dust load during welding, near to the routinely worn ventilated helmets, was in the range of 5-8 mg/m(3). The biomonitoring data of the welders (pre-shift: 88-140 microg Al/g creatinine in urine; 13-16 microg Al/l plasma) showed a high long-term stability but also sensitivity to acute shift dependent exposure changes. The Al welders who had been working in this profession at an average of 15 years showed no significantly increased symptom levels compared with the control group. Explorative regression and covariance analyses revealed neither a correlation between biomonitoring and performance variables nor a significant difference between Al-exposed and controls in the performance courses during the 4 years period. Explorative modelling indicated that the structure of neurobehavioural outcomes could be determined by possible indicators of intellectual 'a priori' (premorbid) differences between subjects but not by their exposure information.

CONCLUSIONS

Compared to studies in the literature this study is characterized by relatively high and non-confounded Al exposure of the welders, a repeated-measurement design, and multivariate analyses. However, the long-term stable interindividual differences of internal Al exposure were not related to interindividual differences in neurobehavioural performances. Additionally, the lack of processual changes of neurobehavioural performances during the observation phase and the insignificant group differences do not make it very probable that degenerative processes caused by Al had happened before study onset or stopped just at this time point.

Elimination kinetics of metals after an accidental exposure to welding fumes

OBJECTIVE

We had the opportunity to study the kinetics of metals in blood and urine samples of a flame-sprayer exposed to high accident-prone workplace exposure. We measured over 1 year, the nickel, aluminium, and chromium concentrations in blood and urine specimens after exposure. On this basis, we evaluated the corresponding half-lives.

METHODS

Blood and urine sampling were carried out five times after accidental exposure over a period of 1 year. The metals were analysed by graphite furnace atomic absorption spectrometry and Zeeman compensation with reliable methods. Either a mono-exponential or a bi-exponential function was fitted to the concentration-time courses of selected metals using weighted least squares non-linear regression analysis. The amount excreted in urine was calculated integrating the urinary decay curve and multiplying with the daily creatinine excretion.

RESULTS

The first examination was carried out 15 days after exposure. The mean aluminium concentration in plasma was 8.2 microg/l and in urine, 58.4 microg/g creatinine. The mean nickel concentration in blood was 59.6 microg/l and the excretion in urine 700 microg/g creatinine. The mean chromium level in blood was 1.4 microg/l in urine, 7.4 microg/g creatinine. For the three elements, the metal concentrations in blood and urine exceeded the reference values at least in the initial phase. For nickel, the German biological threshold limit values (EKA) were exceeded.

CONCLUSIONS

Aluminium showed a mono-exponential decay, whereas the elimination of chromium and nickel was biphasic in biological fluids of the accidentally exposed welder. The half-lives were as follows: for aluminium 140 days (urine) and 160 days (plasma); for chromium 40 and 730 days (urine); for nickel 25 and 610 days (urine) as well as 30 and 240 days (blood). The renal clearance of aluminium and nickel was about 2 l/h estimated for the last monitoring day.