Summary
A semiautomated head-space gas chromatographic (GC) method was developed for measuring formic acid in urine. The method consists of heating 1 ml urine sample in a 20-ml air-tight vial in the presence of 1 ml sulfuric acid and 2 ml ethanol at 60°C for 30 min for ethyl esterification and air-liquid equilibrium, followed by automatic injection of 1 ml head-space air into a flame ionization detector GC. The detection limit was 1 mg/l for formic acid. The method was applied to measure formic acid in the shift-end urine samples from 88 workers exposed to methanol at 66.6 ppm (as geometric mean) and in urine samples from 149 nonexposed controls. Methanol concentrations were also determined. Regression analysis showed that urinary formic acid concentrations, as observed or corrected for either creatinine concentration or specific gravity of urine (1.016), correlated significantly with time-weighted average intensities of exposure to methanol vapor. Men excreted significantly more formic acid than women. Comparison with methanol excretion suggested, however, that urinary formic acid is less sensitive than urinary methanol as an indicator of methanol vapor exposure, primarily because the background level for formic acid (26 mg/l as arithmetic mean, or 23 mg/l as geometric mean) is more than ten times higher than the level for methanol (1.9 mg/l as arithmetic mean, or 1.7mg/l as geometric mean). After theoretical methanol exposure at infinite concentration, the urinary formic acid/methanol ratio should be about 0.4.
Similar content being viewed by others
References
American Conference of Governmental Industrial Hygienists (1991) Threshold limit values for chemical substances and physical agents and biological exposure indices. ACGIH, Cincinnati
Angerer J (1976) Gaschromatographische Bestimmung von Ameisensäure im Harn in Form von Kohlenmonoxid. J Clin Chem Clin Biochem 14:73–77 (in German with English summary)
Baumann K, Angerer J (1979) Occupational chronic exposure to organic solvents. VI. Formic acid concentration in blood and urine as an indicator of methanol exposure. Int Arch Occup Environ Health 42:241–249
Bricknell KS, Finegold SM (1978) Improved method for assay of formic acid by gas-liquid chromatography. J Chromatogr 151:374–378
Deutsche Forschungsgemeinschaft (1991) Maximum concentrations at the workplace and biological tolerance values for working materials 1991. VCM, Weinheim
Dutkiewicz B, Kończalik J, Karwacki W (1980) Skin absorption and per os administration of methanol in men. Int Arch Occup Environ Health 47:81–88
Ferry DG, Temple WA, McQueen EG (1980) Methanol poisoning. Comparison of urinary methanol concentration with formic acid excretion rate as a measure of occupational exposure. Int Arch Occup Environ Health 47:155–163
Heinrich R, Angerer J (1982) Occupational chronic exposure to organic solvents. X. Biological monitoring parameters for methanol exposure. Int Arch Occup Environ Health 50:341–349
Heinzow B, Ellrott T (1992) Ameisensäure in Urin — ein sinnvoller Parameter der umweltmedizinischen Diagnosik? Zentralbl Hyg Umweltmed 192:455–461 (in German with English summary)
Inoue T, Takeuchi Y, Hisanaga N, Ono Y, Iwata M, Ogata M, Saito K, Sakurai H, Hara I, Matsushita T, Ikeda M (1983) A nationwide survey on organic solvent components in various solvent products. I. Homogeneous products such as thinners, degreasers and reagents. Ind Health 21:175–183
Jackson S (1966) Creatinine in urine as an index of urinary excretion rate. Health Phys 12:843–850
Japan Industrial Health Association (1991) Recommended occupational exposure limit. Jpn J Ind Health 33:277–298
Kawai T, Yasugi T, Mizunuma K, Horiguchi S, Hirase Y, Uchida Y, Ikeda M (1991a) Methanol in urine as a biological indicator of occupational exposure to methanol vapor. Int Arch Occup Environ Health 63:311–318
Kawai T, Yasugi T, Mizunuma K, Horiguchi S, Hirase Y, Uchida Y, Ikeda M (1991b) Simple method for determination of methanol in blood and its application in occupational health. Bull Environ Contam Toxicol 47:797–803
Kawai T, Yasugi T, Mizunuma K, Horiguchi S, Morioka I, Miyashita K, Uchida Y, Ikeda M (1992a) Monitoring of workers exposed to a mixture of toluene, styrene and methanol vapours by means of diffusive sampling, blood analysis and urinalysis. Int Arch Occup Environ Health 63:429–435
Kawai T, Yasugi T, Mizunuma K, Horiguchi S, Iguchi H, Uchida Y, Iwami O, Ikeda M (1992b) Comparative evaluation of urinalysis and blood analysis as a tool to detect exposure to organic solvents at low concentrations. Int Arch Occup Environ Health (in press)
Kumai M, Koizumi A, Saito K, Sakurai H, Inoue T, Takeuchi Y, Hara I, Ogata M, Matsushita T, Ikeda M (1983) A nationwide survey on organic solvent components in various solvent products. II. Heterogenous products such as paints, inks and adhesives. Ind Health 21:185–197
Lee EW, Terzo TS, D'Arcy JB, Gross KB, Schreck RM (1992) Lack of blood formate accumulation in humans following exposure to methanol vapor at the current permissible exposure limit of 200 ppm. Am Ind Hyg Assoc J 53:99–104
Liesivuori J, Savolainen H (1987) Urinary formic acid as an indicator of occupational exposure to formic acid and methanol. Am Ind Hyg Assoc J 48:32–34
Mráz M, Flek J, Sedivec V (1978) Is the urinary level of formic acid indicative of man's exposure to methanol vapour? Pracov lék 30:333–337 (in Czech with English summary)
Ogata M, Iwamoto T (1990) Enzymic assay of formic acid and gas chromatography of methanol for urinary biological monitoring of exposure to methanol. Int Arch Occup Environ Health 62:227–232
Rainsford SG, Lloyd Davies TA (1965) Urinary excretion of phenol by men exposed to vapour of benzene; a screening test. Br J Ind Med 26:162–164
Saito J, Ikeda M (1988) Solvent constituents in paint, glue and thinner for plastic miniature hobby. Tohoku J Exp Med 155:275–283
Sedivec V, Mráz M, Flek J (1981) Biological monitoring of persons exposed to methanol vapours. Int Arch Occup Environ Health 48:257–271
Smallwood AW (1978) Analysis of formic acid in air samples. Am Ind Hyg Assoc J 39:151–153
Tada O, Nakaaki K, Fukabori S (1974) On the method of evaluating the exposure to methanol and methyl acetate. J Sci Labour 50:239–248 (in Japanese with English summary)
Tada O, Nakaaki K, Fukabori S, Yonemoto J (1975) An experimental study on the cutaneous absorption of methanol in man. J Sci Labour 51:143–153 (in Japanese with English summary)
Triebig G, Schaller K-H (1980) A simple and reliable enzymatic assay for the determination of formic acid in urine. Clin Chem Acta 108:355–360
Uchida Y, Kawai T, Yasugi T, Ikeda M (1990) Personal monitoring sampler for acetone vapor exposure. Bull Environ Contam Toxicol 44:900–904
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Yasugi, T., Kawai, T., Mizunuma, K. et al. Formic acid excretion in comparison with methanol excretion in urine of workers occupationally exposed to methanol. Int. Arch Occup Environ Heath 64, 329–337 (1992). https://doi.org/10.1007/BF00379542
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00379542