Brit. J . in(lhstr. Med., 1952, 9 , 5 0 . VANADIUM POISONING FROM CLEANING OIL-FIRED BOILERS B Y N . WILLIAMS From t h e London Transport Executive (RECEIVED FOR P UB LIC AT IO N MAY 1 , 1 9 5 1 ) T h e vanadium content of crude o i l a s h varies considerably according t o i t s source. I t ma y b e a s high a s 45%)O i n Venezuelian a nd 1 4 % i n Iranian crude oil.or a s l o w a s a trace i n Wyoming crude o i l a n d none i n th e Pennsylvanian product (Dunstan, 1938). A s fuel oils are residual oils left after t h e distillation o f t h e more volatile hydrocarbons, they will contain a higher proportion o f vanadium than t h e corresponding crude oils. Thus a n o il with a n as h content o f 01%" containing 4 0 % o f vanadium a s V205 would produce 1 l b . o f vanadium pentoxide f o r I 1 tons o f o i l bumt. A significant proportion o f t h e vanadium accumulates i n t h e gas passages o f boilers. This paper describes t h e symptoms a nd clinical findings i n me n cleaning oil-fired boilers, a n d sets o u t evidence that vanadium w a s responsible. After t h e recent w a r a generating station w a s partly converted t o burning fuel o i l owing shortage o f coal. After cleaning t h e oil-fired boilers t h e me n noticed symptoms which they associated with t h e work. Before this conversion there h a been n o complaints from t he boiler-cleaners o f a n y harmful effect o n their health. T h e boilers a re probably t h e largest oil-fired land inistallations i n this country, each boiler consuming about 1 5 0 tons o f fuel o i l p e r week. h e lower part o f t h e boiler, into which i s sprayed t h e atomized oil, i s known a s t h e combustion chamber, which i s lined b y refractory fire-bricks, a n d o n i t s rear a nd side walls a r e t he vertical generating tubes. I n t h e upper part o f t h e boiler a r e more generating tubes interspersed between which a r e t he superheater tubes. Considerable quantities o f petroleum soot a r e deposited i n both t h e combustion a nd super- heater chambers. Each boiler requires cleaning onc e a year i n order t o maintain i t s efficiency, a n d i t h as been found necessary a t these times t o renew t h e fire-brick lining. It takes a gang o f eight me n about five days t o clean a boiler, after which t h e brickkivers enter t o dismantle t h e fire-brick walls a n d build n e w ones. T h e boiler cleaning methods i n u s e when t h e investigation began produced large quantities o f dust. T h e combustion chamber w a s cleaned b y brushing t h e soot off the walls, a n d t h e boiler tubes b y tapping with a rod, t h e soot falling o f f a s a result o f t he vibration. In t h e superheater chamber t h e banks o f tubes h a d t o b e cleaned b y a compressed a i r j e t from a nozzle, a s i t w a s difficult t o reach them b y other means (Fig. 1 ) . Dismantling t he fire-brick walls also produced dust, a nd t h e bricklayers complained o f similar, though less severe, symptoms than those described b y t h e boiler- cleaners (Fig. 2 ) . The scaffolders, w h o a r e t h e first t o enter t h e boiler i n order t o erect t h e platforms from which t h e cleaners have h a d symptoms similar to those o f t h e bricklayers, but t h e cases reported i n this paper a r e all boiler-cleaners. Methods o f Analysis T h e vanadium content o f t he urine samples w a s determined by a colorimetric method described b y Sandell (1950) i n which sodium tungstate i s used. T h e method was checked b y estimating vanadium i n th e urines o f m e n n o t exposed t o petroleum soot, none being detected n these samples, a n d urines t o which known quantities o f ammonium meta- vanadate were added. It w a s found that t h e method w a s accurate i n determining quantities a s l ow a s 0 0 2 m g . p e r specimen. Samples o f dust were collected from different parts o f t h e boilers during cleaning operations. Measured volumes o f dust- laden a i r were drawn through distilled water con- tained i n a n aspirator packed with Lessing rings, a guard aspirator also being fitted a s a precaution. Three separate samples o f 3 7 , 4-5, a n d 6 - 8 c u . m. were collected, t h e a i r being passed a t about 7 1 c u . 5 0
