I
in the Chemical laboratory Edifed by NORMAN V. STEERE, School of Public Heath, University of Minnesota, Minneapolis, Minn., 55455
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aecount,ed far 42y0 of the initial body burden, and suggested that a n additional reduct,ion of 14Y0 of initial body burden may in large part beaceor~ntedfar by loss At s room temperature of 2 5 T tbc of mercury in the form of vapor from the eqr~ilibri~~meonce~~lrstio~~ofmerc~~ryvxpor animals. would be about 20 mg/ma or 200 t,irnes t,he The human organism is able to ahsorb Threshold Limit Value of 0.1 mg/m3 and excrete snbst,antiitl amounts of merrecommended a the meximum atmoscury, in some eases as high ss 2 mg/dsy, pheric eoncentration for the normal work without exhibiting any abnormal sympschedule hy the American Conference of toms or physical signs (8). Since humans (kwernment,sl Hygienists. Compared to not exposed to mercury vapor may have t,his "t,oleranaoU level of 100 pg for the urinary excretion of up to 7.6 pgof mercury IJnit,ed States, Bimm (6) in 1957 reported per day and since t,he mercury excretion of t,he British tolerance level to he 75 pg and exoosed workers mav be hieh for the llle German l.olerance level to be 1 pg/m3, nlthaugh t,he German level was based on work done by Alfred Stock who was known t,o be hypersensit,ive t o mercnry vapor. However, the measurement of mercury in 24 hr mine samples is a scnsit,ive index Absorption of Mercury Vapor of absorption of mercury (21, so that periodic testing of a group or sampling of The met;tbolism of inhaled mercury workers rrho may he exposed to mercury vapor in the rat was reported in 1962 hy vapor could be useful as a means of atHayes and Rothst,ein ( 7 ) in studies ,,sings. sessine whether a n exoosure exists and special exposwe itnit, Hga3 as a tracer, whether ventilstion controls or improved ,znd whole hody eormting techniqnes which cleaning methods are effective. allowed freqneni, estimation of body hwden. They found l.hnt 86% of the mercury WiL8 cleared from inhaled air, Pharmacology of Mercury deposited in (,he lung, oxidized to ionic The pharmacology of mercnry and other form, and ahsortmi hy (be hlood within a hemy mebals was reviewed in 1961 by mat,ter of hours. They report. n sbttdy by Pnssow, Rothstein and Clarkson (9) in an Clarkson in 1961 which showed meremy article which mentions that mercury in in t,he blood to bc bmmd 500/;, to t,he red the body has high affinity for sulfhydryl blood cells and 50% to s e n m prol,ein, with groups, chloride ions, and m i n e s or simple less l.hm 0.174 fillernhle. amino acids, and that mercury inhibits nrease, invert,ase and ot,her enzymes esrryDistribution of Mercury in the Body ing SH groups. Mercury can also hlock In their st,~tdyol t,he mc!aholism of gh~eose uptake by erythrooytes and inhaled mercury vapor in tho rat,, Hayes muscle, produce K + loss from the cells of and Rotlist,ein foiind aft,er exposwes of 5 all species, cause lesions of t,he cent,ral hr to a mereiny level of 1.4 mg/ma that, nervous system, and influence bioolectrie the metal was generally distributed in the phenomena by altering tmnsmemhrane body, hwt became highly loediaed in the potentials snd hy blocking nerve kidney with at, acc~~mnlation aft,er.15 days cnnductilm. of 70% or more of the body burden, or 150 times as high a concentration 01 the metal Symptoms and Signs on s per gram basis than the other tissues. Asswning filterable mercury in blood I n Batbigelli's 1960 review of the literaa t 0.1% they calculate t,he maximrun ture on mercury toxicity from industrial amarmt of nlercllry that could he filtered exposure, the ehitract,eristic signs listed by t,he kidneys in 24 hr after expasore a t for t,he diagnosis of mereurinlism are 0.867, of Lhe body burden, and in comgingivitis, emotionalinstabilityand tremor parison with the actual deposition of of the extremities, with muscular tremor 16.7% of the hody burden conclnde that as the rloquent sign (10). A graphic the extraordinary affinity of t,he kidney example of the efferts of mrmx~lartremor for mercluy is not, related to fill.ralion is provided by t,lle sketches of a. direct phenomena. enrrent meter made by a. repairman while suffering chronic mercury poisoning and Excretion of Mercury 12 morllhs later after complete recovery (20). Figure 1 shows the two sketches. In the rat inhelxlior sh~diesxhont 30% The eyes of 51 direct current meter of the hody burden of mermlry cleared repairmen were examined by Locket and from the body rapidly with a half-time of Naeroo (11) to find out if there were any 2 days, sssociated with a rapid fecal exeye changes following expornme to mercury cretion, and the rest more slowly with 8. vapor; the article reports the findings snd half-time of 20 d w s , with shoot, equal shows four color photographs to demonrates of feral xnd urinary excretion. The study showed thnt excreta. dnring 15 days (Continued on page A530)
XVIII. Mercury Vapor Hazards and Control Measures Liquid meraur)- cnn pnrluce enongh vapor a t ordinary ruom temperaitnes to poison people who iuhsle t,he vapor for s. period of time. Beasnse clevat,ed concentralions of mercwy vapor freq~lently exist in laboratories using elemental mercury, it is important to recognize the phpsialogiesl effects which ran he used to cont,rol mercury vapm I I u r h more work is needed on the 81thjeet of mercury vapur: The in11 range nf physiological effects is not yet undenlood; there is no simple diagnostic test which will predict mercury poisoning; control measures now recognis~rlby many are not Fully accepted by all.
History Records are available lo show that some of the chemical properties of mercury were known in Egypt in 16011 B.C. and in India in 500 B.c., and i n d ~ ~ s t r i poisoning sl hy mercury vapor had been recognized prcviow to the Roman era. (1).
phsrmacologir action, and l.herapy for merrurial diseases in his Von clw Bwg.sxcht und andrren Uergkrankheiten, p~ihlishedin 1 5 I . Ot,her early mtlhors on mercury poisoning included Ellenborg, Fernel, Ramasaini, and Kussrnml (2). The lengths of wmkdnys and the nnmber of days worked per month for mercury miners in Austria were limited as early aa 1665 (31, and in the 1Tnited States in the 1800's mercury was recognized as an indust,rial haeitrd for hsl,l.,ers. Mercury vapor in the laboratory calmed chronic mercury poisoning of Pascal and Faraday, according lo Stock's deductions from their biographies ss reported b y Giese (4), and a. rerent case was reported in 1956 by Goldwater, rt al. (5).
Vapor Pressure and Threshold Limits
Volume 42, Number
7, July 1965
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ings may be found in tables in Bat,ttgelli (10) and Biddmp (2).
Treatment of Mercury Poisoning Altho~~gh tthp most effeeiive method of treatment of mercury poisoning is to remove the paiient from the exposure, Bidstrup (2) and Foreman (15) comment, on the uses and effects of CeNa-EDTA. CaEDTA, BAL, D-pencillamine, and N-ac~tyl-DL-penrillsmine.
Personal Protective Measures I n lxhornlorien where mercum is handled or manipi~lated regularly, as in gas measurements, clothing and shoes used in the 1ahorator.v should not be worn away from the lahmatory, and there should br no smokin~, drinking or eating in tho laboratory. These precautions are necessary to limit the inhalation, ingestion and absorption of men:ury during work and to prevent rarrsing mercury eontaminatiou bo other al'Ct18. The precautions depend upon provision rrf the necessary laundr). service, lorker farilities, and facilities for washing, smoking and eating. A special soap which changes color from orange t,o deep purple in the presence of mercury on the skin is described in Bidstnlp's eac~IIeni litrle reference hook (2).
Measures to Control Mercury
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Figure 1. Evidence of tremor. Top sketch of o direct current meter by repoirmon suffering chronic mercury poisoning from inhalation of mercury vapor shows the intensity d tremor. Bottom sketch mode by the same man 12 months later. after removal from the exposure, shows the great contrast in muscul~rcontrol. Skelrhca apmnr i , ~T o r i c l v 01 Merrvrr and Its h y 1'. Lealev Bidaliup, M.D. courtee" 01n,. D ~ nuntar, ~ ""d~ I ~ iep,od&ed heir u,iliz Lhr n r r m i ~ i o nd l h e puhlishor, Elaeuier Puhiirlti!lo Co.. Amlfenlnm. H o l l o d .
Cwwounds,
Since men:ury can corrode m n y metala and contaminate electrical instruments and other laboretory apparatus, as well as endanger health, there are several argnments for a d e q t ~ s k control measures. One important addit,ionsl consideration t,hat. shonld be given t,o providing control measures is hased on the conseqoenoes in lost time or research effort if a lahoratov has to be t,ediously decontaminated before it can safely he used a.gain. The pertlliar properties of mercury necessitate special ventilation, cantsinment, floor covering, monitoring, and cleaning proredures if mercury vapor is t o he bronpht nnder reasonable control.
Properties of Mercury
worker has been exposed t,o mercury in any concentration, and bhat the reflex does not cause any visual symptoms or lead to more serious ocular disturbance, The symptoms of metallic taste and sore mout,h in womm with chronic mercory poisoning are reported in a.very interesting study (12) whieh inrh~des~nalyses of blood and urine, at.mospherir concentrations before and aft,er control measures, and a aummary of symptoms appearing most frem~entlvin 21) oersons with six months
baa been heat,ed or because of poor ventilation, the mercury poisoning may be acut,e and the symptoms and signs may differ. Severe pulmonary tract irritation (13) or nephrotic syndrome (14) may he the predominant effects of aoote mercury poisoning. Si~mmariesof reports of mercury poieon-
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Journal o f Chemical Education
Not only does mercury have a great density and high surface tension, it has such a low viscosity that, pouring without, splashing and spilling is impassible ( 6 ) . The droplets whieh are formed will roll and b o m r e when they hit the bench or floor, and niay be broken into smaller droplets whirh cannot he seen by the unaided eye. Figure 2 shows droplets smaller than 0.02 mm in diameter which were i o m d on a piece of flooring removed when i t coold not s~messfullyhe decontaminated, and Figure 3 shows a droplet smsller than 0.05 mm in diameter which was not removed when a piece of t,he same flooring was given special cleaning. Cont,rary to the concept that a sloped floor or bench will allow all mercury droplets to roll to a. convenient sump for pickup, the author has frequently observed visihle small droplets adhering to smooth vertical surfaces, a n cupboard doors and on stainless steel surfaces of apparatus. Mercury is insoh~blein water, alkalies,
oxides, which xwy reduce the vapor pressure of the mercury below the tolerance level, but that vibratiou will break the skin and allow atmospheri
