III. TOXICITY OF ORGANIC SOLVENTS

CONTINUED exposure to an atmosphere contaminated with the vapour of organic solvents may constitute a serious health hazard, so it is necessary for those using such solvents in conservation to learn to appreciate their relative toxicities, so that simple appropriate precautions can be taken. Good general ventilation is essential, and a local aspirator provided with a flexible trunking system is desirable both for safety and comfort; also cotton-wool swabs used for cleaning should not be left lying about and bottles containing solvents should be kept stoppered.

The following table lists some of the commoner organic solvents I used in conservation, the relative toxicity being suggested by the figures given in parts per million (p.p.m.) that are considered a lethal concentra­tion on prolonged exposure. b-ny.figure below roo suggests conditions t~~t_ ~re bad and below 2S really dangerous when fumes are inhaled for a considerable. time. As the toxic ratings vary with individual susceptibility and the time of exposure they are to be taken as an indication only. It should be borne in mind that prolonged exposure to small concentrations may be as dangerous as shorter exposure to greater concentrations and that not all poisonous fumes are irritating or have a characteristic odour that would serve as a warning. It is wise, therefore, to play safe.

! Adapted from N . Irving Sax, Dangerous Properties of Industrial Materials (Reinhold N .Y. ; Chapman & Hall Ltd., London), and c. Marsden, Solvents G.lide (Cleaver Hurne Ltd., London) .

358

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APPENDIX III 359

Boiling Flash Vapour Solvent point point toxicity!

CC.) (OC.) (p.p.m.)

Acetone 56 -I9 600 Amyl acetate I49 3I 200

• Benzene 80 -II 25 ~. n-Buty1uru.ne 78 -6 5 ~_"C~~on disnlphide 46 -30 20 , Carhon tetrachloride 77 noin£ IO • Chlorofonn 6I noin£ 50

-DUiiethyl'1orffiamide I53 67 20 - Ether (diethyl) 35 -4I 400

Ethyl acetate 77 7 400 Ethyl alcohol (ethanol) 78'5 I6 Iooo Glycerol 290 I7S Methyl alcohol {methanol} 65 I8 200 Methyl cellosolve (ethylene glycol

monomethyl ether) I2S 4I slight Methyl ethyl ketone (butanone) 80 -6 200 Morpholine 129 43 moderate Petroleum solvents 1 155-200 34-8 500

~ Pyridine . lIS 20 5 Toluene IIO'S 4 200

, Trichloroethylene 87 no info 100 - Xyleilc"(coml.} 138-44 75-85 200

I Parts of vapour per million parts of air by volume at 25° C. and 760 mm. pressure.

2 Distillation fractions 'from crude oil going under various names depending on boiling range and source, e.g. Petroleum Ethers, Stoddard Solvent. Ligroin. White Spirit. etc. (See Appendix IV.)

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