Document QJYOK7NVbyqBOa1OGjx4qymnL

172 PRANK A. PATTY contaminants that have been set by this body in the ensuing time is an indication of the magnitude of the task and suggests the necessity for a change in polioyl This committee includes several recognized, competent authorities in the field'?Jf industrial toxicology, and also represents a good cross section of government>and industry. There is much to be said in favor of such a body, but there are also pitfalls to be avoided. As long as the committee remains large, although it m&y'Jji cumbersome, there is safety in numbers, and the large cross section of opinion maf be relied upon to prevent the group from going too far astray. The most important precaution is that standards set by estimation, as nearly all of them necessarily must be, should not be considered, or portrayed, as ultimate levels of safety fifl, only as tentative levels, representing the present consensus subject to reconside?p tion upon presentation of any properly weighted evidence. Another point that mu' be rigorously guarded against is the overbalancing of the committee in favor.ijtf persons whose training and qualifications are in the field of oratory instead of tit field of industrial hygiene and toxicology. Neither the alarmists nor the purists fah* want to approach zero concentration of all harmful materials are sufficient^ numerous, now, to seriously threaten to upset the proper balance. The opinions^; all qualified and experienced people in the field should be sought. It should be re membered that the most thorough and complete toxicological data are useless un less accompanied by competent chemical analysis of the air, and the air sample must have been properly chosen to represent exposures existing during the petit in which symptoms or manifestations of harmful effects developed, or were demo" sjtrated.jtoj3e_abAent.__________ __... _ ____ ________ _____________,,__,______ CHAPTER VII nmpling and Analysis of Atmospheric Contaminants FRANK A. PATTY tthjjijspi^apter the problems involved in sampling and analyzing air contain* pfdikcussed from a general viewpoint with little regard for individual iaiits.,It is not within the scope of this volume, to give detailed methods of ||ljrather complete compilation of such methods1 has been published preijjiime II of this book outlines of, or reference to, methods of proved ipany the discussions of most contaminants. The methods so presented is6 jto be interpreted as the only good methods, but rather methods that ^. suitable and reliable in practice. Volume III of this book covers sampling and analysis in a more comprehensive manner, lany ^analytical methods available to the industrial hygienist have been simplified until they require little thought or training. On the many seemingly simplfTtests require a fundament5l''understa`nding of `TgSs laws, partial pressures, and chemical reactions. In any industrial rilnent many questions arise that can be answered only by'a qualified iffiiethod of analysis to be used will depend upon the nature of the Ipthd rather than merely upon a "standard method." The trend is award'methods that give prompt results with a1 degree of accuracy suited fitlfafices. eWslpme'the industrial hygienist should adopt regarding analytical methgllfftf^rely upon a method until he has personally tried it out underi Jilions, such as: (1) by sampling a synthetic atmosphere"from a ^apparatus or from a gastight, impervious chamber of sufficient size `"sampling' mixtures without introducing; significant errbrs; flifg' a measured amount of contaminant into a'device'attached to Arrangement in such a manner as to utilize the entire; amount; or (3) gputh a device of proved worth by sampling from ^lipmin'bn miani- rdvet^he^same period of time. - concentrations of atmospheric contaminants of interest to the qs, Analytical Chemistry oj Industrial Poisons, Hazards, aid Solvents. 2nd York-London, 1949. i s r m. )/*' jRfcS&K't, 1: ` 1 ;lp?