Application of mathematical modelling for assessing the biological half-times of chromium and nickel in field studies
A Tossavainen, M Nurminen, P Mutanen, S Tola
1980
Occupational and Environmental Medicine
The biological half-times of urinary chromium and nickel excretion and plasma nickel concentration were calculated for four welders and four electroplaters. A linear one-compartment kinetic model gave estimates of the half-times ranging from 15 to 41 hours for chromium in urine, from 17 to 39 hours for nickel in urine, and from 20 to 34 hours for nickel in plasma. The model allows a precise description to be made of a worker's state of exposure as affected by a varying concentration of the
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... s in the air. Field studies on the kinetics of toxic substances have many practical problems and exposure chamber studies would usually be more appropriate, but they are seldom possible because of the expense of the chamber experiment, and the amount of worktime which the exposed subjects must give up. In connection with exposure to carcinogenic substances, ethical considerations prevent chamber experiments even though such an exposure would be common in industry. Some of the practical problems arising in field studies because of the failure of the workers to comply strictly with the study protocol may be overcome by using suitable theoretical models which can be estimated from and tested even with somewhat scarce and imperfect data. We present a mathematical approach for assessing the biological half-times of urinary chromium and nickel and plasma nickel in connection with occupational exposure to these substances. Materials and methods As this study is based on the data of two previous detailed studies,' 2 the study design and the methods of chemical analyses are described only briefly. CHROMIUM The urinary excretion of chromium was studied in a group of six male welders (mean age 27-5 years, range 21-34). Five of them welded high alloy Cr-Ni steel and one mild steel only (compeer person). In the present study only the four most exposed subjects were included. Air and urine samples were collected during one work-week. The urine samples were collected at 0700, 1100, and 1600 every working day of the week. Air samples were collected with personal samplers each morning and afternoon from Monday to Friday inclusive so that the sampling time covered the whole work period. Urinary chromium analyses were performed with electrothermal atomic absorption spectrophotometry (AAS), and the results were calculated per gram of excreted creatinine. The water-soluble fraction of the welding fume was analysed by both the AAS and s-diphenylcarbazide method which gave identical results within the analytical error of the two procedures indicating that the water-soluble chromium compounds were mostly hexavalent. The precision of the AAS analyses was about 5-10% expressed as a relative standard deviation of duplicate determinations. NICKEL Urinary and plasma nickel concentrations were studied in a group of four electroplaters exposed to water-soluble nickel sulphate and chloride. Three of the subjects were male (aged 29-30) and one female (subject C, aged 43). One store worker served as a compeer. Only the results for the exposed subjects are presented here. Air, urine, and plasma samples 285 on 26 April 2019 by guest. Protected by copyright.
doi:10.1136/oem.37.3.285
fatcat:u2nzw45hm5gj5gqamgnvtxqrku