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Browning, 1965, Toxicity and Metabolism of Industrial Solvents

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Browning, 1965, Toxicity and Metabolism of Industrial Solvents TOXICITY AND METABOLISM OF INDUSTRIALINDUS SOLVENTS) BY ETHEL BROWNING, M.D. Fornrerly H.M. Medical Inspector of factories Ministry of Labour and National Service London h^ p d Yh 1 'y M tilt;ylc ,^cleros;s ELSE VIER PUBLISHING COMPANY AMSTERDAM • LONDON • NEW YORK 1965 ,a. C 37. Methanol severe Synonyms: methyl alcohol, wood spirit, wood alcohol, carbinol some H •f i. The tissues Structural formula: H H owing I rbons; Molecular formula: CH3OH ,eight. i their Molecular weight: 32.042 body a clear colourless, highly volatile liquid with an odour similar to that while Properties: ie for- of ethyl alcohol, and a burning taste. ons of boiling point: 65 °C melting point: —97.8 °C vapour pressure: 95 mm Hg at 20 °C vapour density (air = z): i. i i specific gravity (liquid density) : 0.7915 flash point: 54 °F conversion factors: i p.p.m. = 1.31 mg/m3 i mg/l = 764 p.p.m. solubility: completely miscible with water, ether and most organic solvents. Only a mild solvent for fats and oils. maximum allowable concentration: 200 p.p.m. ECONOMY, SOURCES AND USES R'? Production (i) Natural methanol is produced by neutralisation of the products of distillation of hardwood with lime. The commercial variety contains impurities – i to 2% of propyl and allyl alcohol, aldehyde, methyl acetate, acetone and other organic compounds (Koelsch, 1921). (2) Synthetic methanol is obtained by passing a mixture of CO2 and H2 at high pressure and temperature over a catalyst. This method now produces considerably more methanol than the natural process. The product, though practically pure, can cause poisoning as severe as that of natural wood alcohol, whose toxic action was at one time thous to be due to the impurities contained in it (Lehmann and Flury, 1949) BWj.&,aMs,n p. 40! [911] wY, •L..-,.:euFltii. 312 ALCOHOLS 7 Industrial uses a mixture of as in tl (t) In the celluloid industry (cellophane laminating). (2) In the boot and shoe industry (wood heel covering). (3) In paper coating. (4) In the manufacture of paint removers and varnishes. Paint strippers may. The mete contain methyl chloride and benzol as well as methyl alcohol, as in the fatal case nadoi a reported in the Annual Report of H.M. Chief Inspector of Factories (1957), where animal sl a man engaged in removing old paint from inside a small lift was trapped inside it. The cause of death was notified as 'narcotic poisoning by inhalation'. ^^j.Aasa In the production of formaldehyde and as a general solvent in organic synthesis. (5) Sox (6) In the production of synthetic indigo and other dyes (Fairhall, 1957). methyl a (7) In the straw hat industry, as a solvent for dyes (Wood and Buller, 1904; whether: Baskerville, 1913). have` be • (8) As a rubber accelerator. /kg ? (g) In the denaturing of ethyl alcohol. (Yant'et (io) As an anti-freeze agent. • several h effects.-] blind BIOCHEMISTRY Estimation cases'wa (r) In the atmosphere :.;=Ia t The method of estimation of methanol vapour described by Leaf and Zatman being (1952) and Elkins (1959) is based on its reaction with potassium permanganate, cretedia oxalic acid and Schiff's Reagent (basic fuchsin, sodium bisulphite and concen- In- trated HCI). The curve of transmission on a photometer is compared with that of a known amount of methanol; the sensitivity, 11101 of air are sampled, with the doses_ an midget impinger, is about 40 p.p.m. Rogers (1945) states that the midget im- In] pinger has a collecting efficiency of approximately 92% at atmospheric concen- mate-ar trations of 200 p.p.m. of methanol. maximu a p (2) In blood and tissues 5959): A similar method for blood and tissues was introduced by Hine et al. (1947), intoxicw using steam distillation. When only small amounts of blood are available (0.5 ml) level, w] the vapour may be aerated directly into the oxidising reagent. fatal nE A micro-method, using the reaction of formaldehyde with chrotnotropic acid, metaTol with permanganate as the oxidising agent for the methanol, was devised by • Agner and Belfrage (1947). formakh [ obsrvc (3) In urine The method used by Leaf and Zatman (1952) was based on distillation of 8 a ^ rwawk^^ _ .a! t'aUr''f1FaR L• y ^i 5 ,4:.• +8 Y - J^+r r+r.u n `M t ^ •^' .^ r. MC.s.. Lar aaa.M+^1P^V _ we w.Y- - n.yayT-:^•V„ _ -^ WV.r—. .I•.v.r.ea...I .-...'.•1JO+ q u e^Ip 4- C ,p .^ ` b : U h:FO ^ m ipr .^ u - p o. u o ° Y '3 u o o ° 'ti u y x 6° -: It VJ /^ y - 0 • r• ^^ .^^' N }I a^ 1 " yX'j V u . y U ya l^ '.7 ^^ 6 lQ .N .-+ .- N^+ CY ^ • v' 3 O M te O ate.+ •aU7 v R V O O u G O w a-. 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O ed O e3 4" ^i ^' ^. • • O y y ^b ^` N V U L •^ Y ^"^ CA •n r :^^r • O C CC: alr — ° G'i •2 a w QJ .^+ ^+ p' •1 . v/ z o .a m o r C^ o 3 ed ce '° u "" u u r ti P `" = c °' b c :: w o "' ^' i u w m o i o _ J .^ w (j ,; F °° o .^ v o o ) . ^ ^o v :^ +^ `p u b 8 +w u c°) O k+ ° o p ^, 3 " ? c v ;,G .. 3 !^ a L y^ o^ El iv w au `^ 3 i ;, `.• e^ 3 C u 'c •°- E C C ^, n ' "OO " ' C C >^ a eo ►A. ^, w I, u 3 u 6 3 s E r X n. J w o H e a H ____ 4 C • t 11 f^ • ALCOHOLS 7 37 rT^^? 314 • dory The slowness of combustion of methanol compared with that of ethanol has been In a lal demonstrated by Bartlett (i95o) using "C labelled methanol. In the rat the rate product of proved to be 25 mg/kg/h as compared with 175 mg/kg for ethanol. when the, ai According to Kendal and Ramanathan (1953) there is some excretion of for- methanol CO mate in animals after small doses of methanol which can be suppressed by giving • estinnatedai simultaneous doses of ethanol. It has been suggested by some obse rvers (Roe, brief expose the samenal4 1946; Bartlett, 1950) that ethanol exerts a favourable effect on the toxicity of a . methanol. The rationale of this favourable action is that ethanol depresses the daily to 45d oxidation of methanol and causes an increase in its unchanged elimination in expired air and urine (Leaf and Zatman, 1952). This inhibition of methano l oxidation by alcohol hydrogenase in vitro, even when the ratio of ethanol/metha- nol was as low as i /z6 had been observed by Zatman in 1946; he suggested there- The manife are similar i fore that it would be expected that ethanol would diminish the toxicity of methanol, permitting the excretion in an unchanged condition of a larger fraction with the ea of an ingested dose. (It should be mentioned that this favourable effect of ethanol has been strongly denied by Gilger et a!. (1952) who state that in mice, ethanol increases the toxic effect of methanol and formaldehyde.) metnyi . au ated.: Seve (2) Distribution in tissues case The enzyme mechanism of decomposition of methanol is not completely were dui explainable, but on the basis of evidence that it can be oxidised in vit ro by means has exustea of catalase and hydrogen peroxide, it has been suggested that a similar mechanism acute pois may be effective in vivo (Agner and Belfrage, 1947; Jacobson, 1952). The view include di held by Kendal and Ramanathan (1952) is that formaldehyde itself in the pres- ance .and ence of methanol is converted by alcohol dehydrogenase present in the liver to a vol- ingested'v atile ester of formic acid, methyl formate, which subsequently undergoes slow hy- is usually; drolysis. It was found by Yant and Schrenk (1937) that regardless of the method of administration (oral, subcutaneous or inhalation) methanol is distributed very rapidly to all tissues, and that the amount found in any particular tissue is closely its most 4 related to the amount of water which it contains.
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