Document xzrVdGQMw0w6BxdXE7NrzRKRG

FILE NAME: WR Grace (WRG) DATE: August 1956 DOC#: WRG208 DOCUMENT DESCRIPTION: 1956 Montana State Board of Health report Industrial Hygiene study of Zonolite Company V m m c ih otak-: jxmjid o? iiealth Helam., Hcntana DiVTSIOIT OP DISEASE CONTROL IBi-aii- Kl AW. IiajUSTEI/tL u r o m s . s n M . _ OF TIE e o e o l h 'e c a m m . o:- . . d i l b t * k d c t /jia a ^ t C 9, 1956 Condiictcd by:? Lenjanln F Nalco Industrial !(ygiona Engineor Division of Diooasa Control Distribution;; Thics r-oporb 3 coniMdontiol and is not i'or distribution esccopt to tho raoaiaensnt of tbo Zonolito Company*. ,, V tr V \V> "V ( ( On August Oth and 9th, 1956 an industrial hygiono atudy was made ol` tho Zonolito'Company of Libby, Montana, to dotoraino if.any of tho components of the operation of this company wore detrimental to tho health of tho employe03. Tho study wa3 made nftor a discussion of industrial hygiene principles with Mr, R. A. Blotch, Division Manager, nxl Mr. D. Lovicl:, Assistant manner. Mr. i/ altor Bairsr, Assi-stant Plant Manager, arid Mr. Ted V,'right, Ropairmun, acted aa guides for the study. Tho present study involved 'tho conduction of an engineerin'; investigation to valuato the working environment and by malting a determination of tho environ mental factor's which might have a bearing on health. C0n3 ld0.rati.cn v/as also given to tho ventilation ana other protective) mmvumros already in uso for the control of dust and other toxic material::;. Tho samples collected ware analyzed and counted in accordance with accepted practice generally recommended by tho U. 3* Public Health Service, tho African Conference of Governmental Industrial Hygienists, arid othor official agencies. Samples collected for duat counts woro counted a few hours aftor they woro collected and woro analyzed' for free silica in the U. 3 Public Health Service Laboratory in Cincinnati, Cliio. ' .'icr'iuti m e; On-rations Tho description of tho operations of this company have been adequately discussed in pruviews reports. but, in general, they constituto an bpon cut mlno, a transfer point from tho mint to tho mill, and various milling and Dicing operations done un five floors of tho company's rill, a short distance from the mine. Thu operation, in general, io chut of reducing in oizo tho vormiculit0 ore which is mined in tho open cut mine to various graded sizes which aro boat for tho product which Is ultimately an insulation material. In grading anti siring, various vibrating screens aro employed to obtain tho sices necessary and to reduce tho amount of extraneous material from the ore. In tho mining operations, approximately 17 men aro employed per shift ana, sine tho operation Is almost wholly outdoor work, no sampled for dust concenytrations were collected in this area. At the transfer point from tho mine to the mill, one nan la employed and, although there is soma dustiness, it was not felt to l>a significant and no samples woro collected at this point. In tho mill proper, operations ato divided into wot mill and dry mill production. In tho v/ot mill, dustine30 la quite low; however, in the dry mill the dust from the various sizing and grinding operations is quite high, as noted in the Table 1 V ( Tho approximate populattea in the- plant at tho time of thin study vras 100 workers, aa against 34 worker in 1944, when the last study of tho plant was cade, The-population of tho plant a few dayo before the study was considerably higher but, duo to a reduction in the demand fox* the product, one ehift v&3 laid off. , Sample No. , 1 2 3 4 5 6 TADT.E I DUST CONCENTRATI0N3 IN JHK AIR T.-ccatJon \fct nil! Gar.oral nir aomplo. Ccnoontratlon irt nvppof^ 11 6 Forcent Froa Silica Hot determined Dry mill h'th floor (.moral air Sample 17 9 . 1.8 (rafter sample) Dry mill 4th floor General air aample 51. tf Not determined Dry taill 3rd floor General nir oample 20 7 ' 1.0 s (rafter sample) Dry mill 2nd floor Gonoral air 48.3 Not determined Dry mill let floor General air sample 83.0 (rafter sarnie) Not! Composite air aample all floors provided free eilica determination of 1*5?' Maximum allowable concentration: . . Silicas High (above 50/ froa SiOo) - 5 mppcf Medium ~ (5 to 50fi free SjOgj - 20 mppcf : Low - (bolow % froo S ^ ) - 50 mppcf / - . Dust (nuloanco, no free silica - 50 mppcf fcmilliena of particles p?r cubic foot of air. Concentrations The concentrations of dust in the air, on determined in tabla I, vary consid erably from a low of 11.6 to a high of 83 mppcf, These concentrations in relation to free silica or not excessive, although tho concentrations on th fourth, second and first floor were at or above the maximum allowable concentration even for a nuisance dust with no free uilica, On the basis of the asbestos content, no state ment can b-made?, since at this tlmo the asbestos content of the dust has not boon determined, Howovor, from visual observation and from information gained at tho (. plant, ft Gmail pei*ocntag@ incxvos in the asbestos content of tho material being processed produce^ several tixr.es creator concentration of duet in tho air The maximum allowable concentration for aabostoo is 5 tnppcf, and when the concentra tion of asbestos in the dust samples collected has bean dotmined, further com menta on tho concentrations will ba made. At this timo, however, and on tho basis of the concentration of asbestos found in the dust, which varies from tho company*0 records from 8 to Z1&, it would appear that tho maximum concentration of dust in th* air should not bo greater than 25 to 30 rappef. Toxicity A review of tho literature indicates that voralculito or tho dust from tfyis uatcriol is not especially toxic and is generally included only eo a nuisance dust. However, tho asbestos dust in tho dust in tho air 5s of considerable toxi city, and 1w a footer in tho consideration of x'eiuolng dustiness ixx this plant. According to Drinker and H a t c h ^ , tho pathologic changes produced by csbostccs are xxot like thoso of silicosis. The asbestos fibor group about the nock of tbs small air sacs In tho lungs, and stimulate tho formation of a diffuse fibrosis. There ia no dofiiiito nigration or transportation of the dust particles to the lymph nodes and no formation of tho fibrlo nodules. As tho fibrosis increases, tho reduction ixx lung nro>n causes a serious dccreaso in lung capacity, or difficulty in breathing, Lau?.'A`-' euggeoted that enlarged hearts noted frequently in tho cases of secondary aobeutoaia rosy bo the result of tho increased work with tho heart resulting from this condition* It takes mono work to pump tho blood through tho esbestotic than through thy normal lung. A-xirr/u All enable Concentrations In the study of art emrix'onnont from the standpoint of exposure to harmful matorlaln, tho uao of maximum allowable concentrations ia helpful, Maximum allowable concentrations ia defined as that concentration of any hamful material in a working atmosphere bolew which a worker*!) health will rxot be affected adversely ikud.mum allowable concentrations havp boon established upon many of the common in dusttrial poisons and they havo been based on tho results of correlated opgineering and medical studies in industries using theso materials. Maximum allowable coneon- trationc now in uso r.o a criteria for the protection for the health of the workers or subject to change os additional information is accumulated. The concentrations usod in this study nro those recommended by the U. 3. Public Health Service, tho American Conference of Governmental Industrial Hygionioto and tho American Industrial Hygiene Association. All maximum allowable concentrations recorded are for pro longed exposures or theso exposures for an eight-hour working day. In tho evaluation of tho worker's exposure to any harmful material, cog .nizonce of the amount of time opont by the worker in tho contaminated atmosphere should bo to!con* For this reason an attempt was' mado to determine tho amount of time a worker spent on all hia jobs whore they wore not continuous. Weighted avorago exposures more nearly represent a workers actual exposure over an eight-hour day than flj Drinker, P., and Hatch, -T.t Industrial Duot, 'McGraw-Hill Book Co, How York, 1954 (2) lansa, A* J., McConnoll, W. J. and Pehnel, J. W. i Effocts of tho Inhalation of asbestos dust on tho lungs of anbojto3 workoxnj, "Public Hoalth Reports", 50:1 of 1935* ' - 3- * ( ( does a oinglo uanpl result representing an exposure for a short portion of an hour /fr a day* ' coneontration of material >: hours exposed Weighted Average hours worked * ~ ' ' * Conclusions nnd Itoconeiisndqtlono - From obacreations rand at the tiro of t.ho study It would appear that t'. .0 was .exhauat mechanism for allaying dust gonornted by tho various vibrating machines and other moving parts in tho dry nil!,, in particular, well designed originally but under tho handicap to which this exhaust mechanism is oubjooted it cannot end dees not function. properly, Tito follcAninij era oovoral reasons wiry tho dustiness in tho dry mill in heavy and why tho exhaust nujchanlora, go designed, does not function* 1 I'vst vibrates alsrcat ccctinuounly off tho rafters which have bocomo loaded aid are continually loaded with dust generating f m a many sources 2. Rubber eonnoctci'a bU;con tho vibrating acroons and tho feed operate ora not tight, nor 0:00 they replaced when they vibrato off or they era worn out, 3 Rubber'connoctcre lotwcon tho vibrating ocroon and tho exhaust ducts are either broken* minsing, or are not placed on tho ductsa 4' Exhaust from oono of tho vibrators io Insufficient to control tho dust generated,which, in all probability, is canned by an over-load of tho system I'rcn other portiOil'; of tho plant, 5 Facia era off many cf tho vibrators, making the exhaust mechanism pro vided ineffective raid, in effe t, n^cing it wholly inoporative duo to tho largo area from which tho exhaust draw's. 6* There arc many hole:; in conveyor pipes in ouch places as stop gates, ccnnectiona to vibrating scream, and do'no of othor points whoro holes have boon cut Into tho -pipes at rand cm locations, or who.ro tho pipes havo broken by vibration or worn through by friction cf tho moving ora. 7 Hoods aver mary of the vibrators aro broken, havo not bcon replaced or are inoffactive, I I would appear that canvas or a resilient typo covor over the vibrators would ba more offeetivo than rigid typo hoods which havo boon provided, ' B , Many of tho transfer points fre-.a one bolt to another aro not exhausted and contribute a great deal of dust to the atmosphere, 9# Many of tho dead ends in tho exhaust oyotem uoro loft open permitting a large volume of air to bo drawn in through openings whoro no control was neces sary, thereby reducing tho control velocity in volumes of air at more critical points . v. . 10 In many locations it was obvious that the dust collection mechanism was full of dirt or dust and could not bo expected to function satisfactorily because of many of th reasons already mentioned. 11, Many of tho elevator housings and screw conveyor housings are opsn in ~ 4~ several places where holes have boon out for various reasons and the housing material removed and not ronlncod, These elevator hcooing and acre'.; conveyer housings are particular offenders in production of dust. 12# It was notod during thin'study that holes wore bo trig cut in the exhaust ducts at random without any provioua calculation as to tho volumo of air required, or tho reduction of air volume to other locations. The junctions wore often left exceedingly rough increasing tho frictional resistance in tho collection pipa. 13#- In ooms of tho locations, particularly on tho vibrating ecroons on tho top floor, it ia obvious that a great deal of product is boing withdrawn through the exhaust oyatoa by virtue of too reach air being drawn through tho system. It is quite probable that tho reason for thin pick-up of product ia because of tho imbalance created for the various reasons previously notod# 14* In BUErary, tho foregoing pointo are illnatrativo of what would bo poor policy in matters of maintenance and operation of this plant# Tho following recommondationa ora booed on tho observations presented and on tho boots of tho dust counts, silica content, end asbestos content of tho dust. It will bo rccognir/jd that tho following roearncndations aro particularly broad and non-specific j until uch a tires as the general over-all maintonanco and repair of existing duct work, both in tho exhaust system and the 01*0 feed pipes have bean sufficiently repaired, no specific rocoamondations appear to bo justified. General rocGrncndn- tlona ore m follows* 1. That all of tho unnecessary oponinga in tho ontir-o exhaust oyster.,, both in the wot aid dry mills bo closed proporly and a program of di3crhd.natory .cutting of pipes bo initiated. All access dears, comors, etc., should bo provided with tight seals and, of great practical importance, aro so designed that they aro easily closed and secured by quick-loc!cing devices in place* of tho usual bolts and nuts Access doors should be attached by hinges to avoid tho frequent damage which occurs when ordinarily manhole plates aro removed for inspection and maintonanco work# An objective in designing tho access ohould bo to raoko it difficult to keep them open* 2. That oil of tho unnecessary openings in all of tho ore transport ducts" and in all tho elevator housings and aersw convoyors bo tightly and completely closed and that all tho broken portions of tho oyatem of tho plant ba adequately repaired. . 3 That all of tho covers on tho bucks of tho vibrators bo replaced and made as air tight as poaaiblo aid that tho hoods ovor tho vibrators bo repaired and replaced with a typo material that will not die integrate subject to vibration# 4. That all of tho exhaust ventilation'duct work bo oxamindd foot-by foot and all holes plugged and unnecessary openings, particularly at doad ends, bo adequately closed and tho entire system bo oloaried of dust which has deposited in any portion of any of the exhaust pipes. 5 That all of tho transfer points'end points where oro is boing deposited into open containers ba adequately ncloood and provided with exhaust ventilation# 6. That a system of vacuum cleaning or other cleaning of the rafters in tho entire mill be institttfccd after the other measures have boon adequately ` t- accoapliehod oo that tho dust load contributed by that dust falling off raftora will be eliminated. Full recognition should ba given to tho fact that direct control measures alone aro usually not enough to insure uafo working conditions. The method of operations, propar maintenance of equipment and of housekeeping tro equally essential to maintain hoaltliful conditions* 7* That until ouch time an the repair and maintenance of both the exhaust arri ore convoying systems have been complete, all tho men in tho dry mill bo provided with and required to wear an adequate respirator, as indicated In tho accompanying list. 8. 'That tho operators of tho spray painting equipment bo provided with a. respirator approved by tho Bureau of Mines for ouch opox*ation as Indicated in tho enclosed psmphlot. ''9* That it bo initiated m a policy of tho company to bo particularly discriminating in tho provisions for any holes or outlets to bo cut in any exhaust ventilation duct or any or conveying duct or apparatus and that, if any ventilation must bo provided for any process, tho quantity of ventilation required bo edoquatoly determined before any exhaust capacity is taken freu existing linos and that the result of such capacity will bo ascertained on ell subsequent units when such capacity has boon involved. ~ S --