Showing papers in "Occupational and Environmental Medicine in 1966"

The Mechanics of Aerosols

Abstract: a time as one year after leaving the Rehabilitation Unit, and about one quarter were not in competitive jobs but were in sheltered employment. Only just over one quarter were still working in ordinary jobs. Their average wage was £8 I is. 6d. Furthermore if one compares the type of work these patients were able to perform there was a definite decline from their premorbid position. The social class grouping before and after rehabilitation was Class II, i-i, Class III, 9-3, Class IV, 4-6, and Class V, IO-I4. Indeed the authors report that 'even the least handicapped of these patients presented continuous problems . . .' and it is noted that such a programme requires special personnel and a great deal of work. Comparing these results with the extra cost in personnel, time, and effort (which could be directed elsewhere) a Doctor Beeching of the psychiatric services would probably scrap such a rehabilitation service before it even started. But is this the right way of looking at it? The authors point out that such a programme, if applied throughout the country, would affect about 6,ooo patients. If the failure rate were the same as in this experiment, about I,500 would be rescued from a disabled life in a mental hospital and once more returned to an at least partially useful and, one assumes, more satisfying life. Obviously more is involved here than mere economics. We were interested to read that as regards behaviour at the Rehabilitation Centre and during the follow-up year 'There were no outstanding differences' between the schizophrenic and the non-schizophrenic rehabilitees. It appears that the group of schizophrenics had difficulties in social adjustment which were even greater than those of work adjustment. '. . . the men concerned had greater difficulty in living outside hospital, than in working outside hospital. If, however, adequate arrangements are made to cater for these various needs, there seems to be every reason to expect that a small selected group of long stay schizophrenic patients can be successfully resettled in work.' The experiment and the report show the high standards we have come so confidently to expect from Dr. Wing and his colleagues, and the publication will be read with interest, not only by psychiatrists, but by all those concemed with rehabilitation problems of chronically disabled patients. J. HOENIG

The Toxicity of Paraquat

Abstract: Samples of paraquat dichloride and paraquat dimethosulphate are equitoxic when the LD 50 is expressed as mg. paraquat ion/kg. body-weight. There are wide species variations in the LD 50 and, of course, variations according to the route of administration in a single species. The pathological lesions attributable to paraquat are described in some detail. Among the most unusual is a peculiar proliferative condition in the lungs, which in an extreme case and in many parts can hardly be recognized as consisting of pulmonary tissue. With slight variations, the same microscopical picture may be seen in the rat, mouse, dog, and man, and less often in the rabbit. The experimental evidence suggests that once the condition is initiated it often proceeds in the absence of further exposure to paraquat until it becomes lethal. There is evidence that much of the mortality resulting from dermal application of paraquat in the rabbit is caused not by percutaneous absorption but by oral contamination from the stratum corneum. This leads to glossitis and oesophagitis and an inability or unwillingness to eat.

Peripheral Neuropathy in Rats Produced by Acrylamide

Abstract: Acrylamide produces ataxia and limb weakness in rats when given in repeated oral doses of 25 100 mg./kg. at various intervals or mixed with the diet in concentrations of 100 to 400 p.p.m. An electrophysiological and histological study of peripheral nerves has been carried out in chronical poisoned rats. In animals with severe clinical abnormalities, motor nerve conduction velocity in the fibr supplying the small muscles of the hind paw was reduced to approximately 80% of the control value. Histologically, degeneration of axis cylinders and myelin sheaths was found in peripheral nerve affecting predominantly the distal parts of the longest fibres. When paralysed animals were no longer given acrylamide, they recovered clinically, conduction velocity returned to the normal range, and there was histological evidence of regeneration of nerve fibres.

Absorption and Excretion of Diquat and Paraquat in Rats

Abstract: The fate of 14C-labelled diquat and paraquat after oral and subcutaneous administration of single doses has been studied in the rat. By both routes of administration the radioactivity usually appears in the excreta within two days. In a few cases a small amount is excreted in the urine on the third day or in faeces on the fourth day. After an oral dose of paraquat no radioactivity could be detected in bile, and with diquat less than 5% of the dose appeared in bile within 24 hours. Both diquat and paraquat are poorly absorbed from the gut, and after subcutaneous administration little or none appears in faeces. By comparison of the measurements of radioactivity with a specific chemical test for diquat and paraquat, the presence of a small amount of metabolites in the urine after oral dosing has been detected. As no such metabolism has been observed after subcutaneous administration it seems probable that there is some absorption of degradation products formed within the gut. It has been shown that about 70% of an oral dose of diquat and about 30% of a dose of paraquat is present in faeces as metabolic products. In vitro experiments have shown that this is probably due to microbiological degradation in the gut.

The Anaemia of Lead Poisoning: A Review

Abstract: Lead intoxication has been recognized as a clinical entity since ancient times Hippocrates (370 BC) was probably the first person to associate lead with clinical symptoms, since when the harmful effects of lead on the body have been well documented Early observations culminated in the brilliant monograph of Tanquerel des Planches (1839) in which the clinical aspects of the disease were completely outlined and most of the early signs of the disease were mentioned So complete was this work that virtually nothing has been added to des Planches9s observations since their publication The earliest reference to lead anaemia was made in 1831 by Laennec, who described thinness of the blood and pallor of the tissues in cases of lead poisoning at necropsy The first direct evidence of the effect of lead on red blood cells was presented by Andral and Gavarret (1840), who counted the number of red blood cells in cases of lead poisoning and found the count to be much lower than normal Since these early reports a great deal of work has been undertaken to try to discover the means by which lead causes anaemia, but it is probably true to say that at the present time this mechanism is still not fully understood This review is an attempt to draw together at least some of the theories which have been advanced in the past and to present them, it is hoped, in an easily accessible manner for future workers in this field

Chronic Toxicity of Aluminium in Rats and Mice and its Effects on Phosphorous Metabolism

Abstract: In mice the oral LD 50 values of aluminium chloride and aluminium sulphate were 0·77 ± 0·12 and 0·98 ± 0·09 g. Al/kg. (± S.E.) respectively. Mice and rats were fed on a normal diet containing about 170 p.p.m. of aluminium. Doubling this concentration caused a decrease in growth in the second and third generations of mice. A high intake of aluminium sulphate (2,835 p.p.m.) caused a 20-fold increase of aluminium retention in white rats. Aluminium accumulated in various tissues, especially in the skeleton, liver, and testes. A high rate of intake (2,665 p.p.m.) caused a negative phosphorus balance in the rat, with an increased output of phosphorus in the faeces. The lower absorption of phosphorus was also demonstrated with Na 2 H 32 PO 4 . Chronic and acute poisoning by aluminium chloride caused, after intraperitoneal Na 2 H 32 PO 4 , decreased incorporation of 32 P into the phospholipids and nucleic acids of various tissues in the rat. It also caused a fall in the adenosinetriphosphate acid-levels in plasma, and a rise in the adenosine diphosphate level. The results suggest that the toxic effects of aluminium salts result both from decreased absorption of phosphorus and from interference with phosphorylation processes in the tissues.

Acute cadmium fume poisoning. Five cases with one death from renal necrosis

Abstract: This paper describes the accidental poisoning of five workers by cadmium fume. The men were dismantling a frame of girders in a confined space by cutting bolts with an oxyacetylene burner. They were unaware at the time that the bolts were cadmium-plated or that this presented a serious industrial hazard. The paper sets out to give an appreciation of acute cadmium poisoning, the characteristics and uses of cadmium, and a review of the literature. The clinical picture of these cases is described, with the pathology of the fatal case which showed severe pulmonary oedema, alveolar metaplasia of the lung, and bilateral cortical necrosis of the kidneys. The lungs contained 0·25 g. cadmium oxide (CdO) per 100 g. wet specimen. An attempted estimation of the fatal dose of CdO fume is made. From the post-mortem findings, using an assumption that 11% of inhaled CdO will be retained in the lungs, approximately 51·7 mg. CdO fume must have been inhaled by the fatal case. As he worked for five hours with a probable ventilatory rate of 20 l./min. the concentration of CdO in the air breathed would be of the order of 8·6 mg./m.3. An estimation of the dose from a study of the working conditions proved unsatisfactory due to certain variables listed in the text.

Trichloroethylene: A Review

Abstract: The physical and chemical characteristics of trichlorethylene are discussed together with its uses in industry and medical practice. Chemical and physical methods of the estimation of trichlorethylene in air have been described, including the use of gas detector tubes, which today is the method most commonly employed. The metabolism of trichlorethylene was systematically investigated by Butler (1948), who in animals established the identity of the main metabolites appearing in the urine, Powell (1945a, b) having also done this in human subjects. The excretion of these metabolites has since been repeatedly investigated, but the intermediate breakdown products within the body as well as the organ mainly responsible still remain uncertain. The acute toxicity of trichlorethylene, manifested preponderantly by central nervous system effects, came to be recognized during the second decade of this century, not long after its introduction as a substitute for benzol as a degreasant in Germany during the First World War. The recognition of a possible chronic toxic effect, characterized by a mild psycho-organic syndrome, came much later and is still not universally accepted. Damage to the trigeminal nerve after closed-circuit trichlorethylene anaesthesia was observed soon after its introduction as a general anaesthetic 30 to 40 years ago, and it was shown to be due to breakdown to dichloracetylene in carbon dioxide absorbers. The pure substance seems otherwise not to have a specific effect on this nerve. The balance of opinion, based on human observations and on animal experiments, is against a severe toxic effect on the liver, although individual cases of liver damage in industrial workers have been reported. The sudden fatal collapse of young workers during mild exercise has on rare occasions been described, there being in most cases an element of heavy exposure. Investigations on man and animals indicate that pure trichlorethylene has no severe effect on other systems of the body. Maximum permissible levels for trichlorethylene in air were reduced from 400 p.p.m. in 1947 to 200 p.p.m., and in 1961 there was a further reduction to 100 p.p.m., which, except in the Soviet Union, is at present accepted in most parts of the world.

Sudden illness as a cause of motor-vehicle accidents

Abstract: Forty-one of the 44,255 road accidents reported to the police in one region of Sweden during 1959-63 were, or probably were, caused by sudden illness in the driver of a motor-vehicle. All 41 were males. The illness was most often due to epilepsy or myocardial infarction. Eight drivers died at the wheel from their disease. No other persons were killed in the 41 accidents. Only in 19 out of the 41 cases was there any possibility of a previous medical examination having indicated that the man was unfit to drive. In view of this, and the extremely small proportion—about 1 in 1,000—of accidents caused by sudden illness at the wheel, there is little point in providing for general measures such as periodic medical examination to prevent these accidents. Attention should be directed to other types of accidents and other groups of drivers.

Incidence of Hypertension among Lead Workers: A Follow-up Study based on Regular Control over 20 years

Abstract: Three hundred and sixty-four workers employed in an accumulator factory had at least three bloodpressure determinations during 1962 in a study of the relation between lead exposure and the incidence of hypertension. In this group 46 workers were found to have hypertension; the expected incidence was 51. Two hundred and seventy-three of the total group, all over 35 years, had been employed for a sufficiently long time to be considered as having had a long-term exposure to lead. On the basis of urinary coproporphyrin tests, they were divided into a `lead-affected9 group (141) and a `non-lead-affected9 group (132). There were 22 persons with hypertension in the former group, and 20 in the latter. There was no significant difference in the appearance of hypertension in these two groups either from the standpoint of age or from the duration of exposure to lead. Two hundred and sixty-five workers had been employed at the factory for 10 or more years, and 82 of these for more than 20 years. There was a positive correlation between the incidence of hypertension and the duration of employment, but no difference between the `lead-affected9 and `non-lead-affected9 groups. This observation is understandable in view of the increasing incidence of hypertension with advancing age. The study shows that workers in an accumulator factory, in which the working conditions are inspected and controlled regularly and in which the workers themselves are examined regularly for the influence of lead, are not more prone to hypertension than the general population. In view of the possibility of vascular damage after exposure to lead, blood pressures in lead-workers should be watched, and treatment started early if hypertension is found.

Toxicity of Triphenyltin

Abstract: The toxicity of triphenyltin has been determined after its acute oral and intraperitoneal administration in rats, guinea-pigs, rabbits, mice, and hens, after feeding it to rats and guinea-pigs, and after its application to the skin of guinea-pigs. The guinea-pig was the most sensitive species and its growth was inhibited by as little as 1 p.p.m. triphenyltin acetate in the diet. With higher concentrations in the diet the relationships between the dose and the survival time and between the amount consumed and the acute oral LD 50 indicated that triphenyltin accumulated in the guinea-pig. Compared with those of triethyltin, the effects of triphenyltin appeared relatively non-specific, but there was evidence of an action on the central nervous system although cerebral oedema did not occur. The effects of triphenyltin were quite different from those of diphenyltin which acted mainly as an irritant. Triphenyltin did not readily penetrate unbroken skin. The use of triphenyltin as an agricultural fungicide is considered in the discussion.

A Comparison of Changes in Pulmonary Flow Resistance in Healthy Volunteers Acutely Exposed to SO2 by Mouth and by Nose

Abstract: On separate occasions, healthy male volunteers were exposed either by nose or by mouth to one of two concentrations of sulphur dioxide, 15 and 28 p.p.m. Exposure to SO2 lasted 10 minutes. Pulmonary flow resistance (R1) was measured by the oesophageal catheter method, and the lung volume was measured by a modification of the gas-compression method; when SO2 was administered by nose, nasal flow resistance (Rn) was measured by means of a catheter placed in the posterior pharynx. The increase in R1 was greater when SO2 was administered by mouth than when it was administered by nose. Similarly, irritative symptoms of the posterior pharynx and chest were more common during exposure by mouth. These findings suggest that the mouth is less effective than the nose as an absorptive surface for SO2.

The Safety of Drivers with Chronic Disease

Abstract: Six hundred and twelve drivers with chronic disease, mainly diabetes, cardiovascular disease, renal disorders, and diseases of the sense organs, were investigated with regard to the frequency of road accidents and serious driving offences during a 10-year period. Road accidents directly caused by the disease or its treatment occurred in four (0·8%) cases, all due to hypoglycaemic attacks in insulin-treated diabetics. A comparison was made between the investigation series and a control series identical with regard to number, sex, age, and duration of licence-holding. About 50% of the drivers in each series were asked about their exposure to traffic; this proved to be similar in both series. The percentages of drivers experiencing road accidents were 4·1 in the investigation series and 7·7 in the control series. The corresponding figures for road accidents and serious driving offences taken together were 9·8% and 15·3%. The conclusion is drawn that any increased risk to road safety constituted by drivers with the specified chronic diseases may be satisfactorily offset by the restrictions applied in Sweden in the granting of licences to these drivers.

Studies in Lead Poisoning. Oral Therapy with Penicillamine: Relationship between Lead in Blood and Other Laboratory Tests.

Abstract: Fifteen workers with lead poisoning of varying degrees were treated with penicillamine given by mouth. The effect on symptoms and pathological laboratory values was satisfactory, side effects were generally mild and the drug is considered to be a good alternative to Ca-EDTA, which must be given intravenously. Previous studies on the reliability of different laboratory tests in evaluating the degree of lead poisoning and the effect of the therapy were extended with special respect to the lead levels in blood. The correlations between lead in blood and lead in urine, coproporphyrins in urine and lead excreted during treatment were of the same order as those found between delta-aminolaevulic acid (ALA) in urin and the same parameters. As could be expected, the correlation between the initial values of lead in blood and ALA in urine was very strong (p It is concluded that penicillamine is efficient and useful in the treatment of lead poisoning. Determinations of lead in blood and ALA in urine are equivalent as expressions of lead poisoning, provided that the lead level in blood is not temporarily raised because of an acute exposure.

Blood lead and haemoglobin in lead absorption.

Abstract: In an analysis of blood lead and haemoglobin estimations from 655 lead workers, there was no indication of any change in the haemoglobin until the blood lead exceeded 110 μg./100 ml.; the slight fall at higher levels of blood lead was not significant at the 5% level of confidence. Sixty-seven men who had blood leads greater than 90 μg./100 ml. were examined clinically. One had a low haemoglobin but none had symptoms or signs that were likely to be due to lead absorption. A further 18 men had haemoglobins of 89% (13 g./100 ml.) or less. None was thought to be low due to lead absorption. The absence of symptoms, signs, and low haemoglobins in association with relatively high blood leads is unlikely to be due to errors in blood lead or haemoglobin estimation. Alternative possibilities are that there were no susceptible workers among those studied; or that the stable conditions of exposure in this population allowed the development of relatively high blood leads without other evidence of high lead absorption. When the haemoglobin is abnormal, blood lead observations may be more meaningful if a correction factor, approximately equal to [Formula: see text] is used. It is concluded that in a population where sophisticated lead control is practised no purpose is served by estimating haemoglobins in all lead workers every three months, but only in those whose blood lead is likely to be in excess of 110 μg./100 ml. It may also be of value in the first year of exposure to detect susceptible workers.

Rheumatism in foundry workers.

Abstract: In order to investigate loss of work from rheumatic diseases in the metal trades, employees in 10 foundries were questioned. Of 325 foundry workers aged 35 to 74 years, who had worked for at least 10 years on the foundry floor, 299 were examined clinically and radiologically for evidence of rheumatic disease. Radiographs of the hands, knees, and dorsal and lumbar spine were taken as a routine, and the pelvis was included in those aged 45 and over. A comparison was made with a control series of radiographs, from men, matched for age, in a random population sample examined earlier in the town of Leigh. Rheumatic complaints in general were less frequent in the foundry workers than in the random sample, and the foundry workers less often gave a history of prolonged incapacity (three months or more) due to this cause. Radiological evidence of disc degeneration in the lumbar spine, however, was more frequent in the foundry workers than in the controls and was of greater severity. Further, the foundry workers more commonly had symptoms and signs of lumbar disc prolapse. On the other hand, the controls had more osteo-arthrosis of the hips and knees and lost more work from pain at these sites. This was associated with a difference of body habitus, obesity being less frequent in the foundry workers. Foundry workers directly exposed to hot conditions did not have less back or leg pain than those not so exposed despite a greater prevalence of disc degeneration. Measurements of air temperature, humidity, and radiant heat were made in a foundry while pouring was in progress. The air temperature rose from 18°C. to 26°C. and the humidity ranged from 70% to 54%. The mean intensity of radiation incident on the clothed surface of a foundry worker was 0·12 watt/cm. 2 . This was compared with conditions during therapeutic exposure to radiant heat. The radiant heat under conditions of `heat therapy9 varied between 0·16 and 0·37 watt/cm. 2 . The possible influence of radiant heat on the prevalence of rheumatic complaints is discussed.

Diurnal Variation in Ventilatory Capacity. An Epidemiological Study of Cotton and other Factory Workers employed on Shift Work.

Abstract: The change in F.E.V. 0·75 during a working shift was studied in a random sample of 473 men employed in three cotton mills in The Netherlands working a three-shift system. Results were also obtained for 198 men, not exposed to industrial dust, who were working in a biscuit factory and two textile factories in the same area. The men were seen only during the shift on which they were working at the time of the study. Men with byssinosis gave a typical picture of the effects of cotton dust on susceptible workers: a generally low F.E.V. with a marked reduction during the shift; –0·16 l. on the early morning shift, and –0·25 l. and –0·33 l. respectively on the afternoon and night shifts. Men without byssinosis in the card and blow rooms showed mean changes in F.E.V. during the shift similar to those of men working in the spinning room: a slight rise in the early morning shift of +0·02 l. followed by a fall in both afternoon and night shifts in the region of –0·10 litres. This pattern of change was also found among the workers in the non-dusty factories. The rise in the early shift cannot be explained by the clearing of mucus from the air passages; cotton workers without respiratory symptoms and men in the non-dusty factories who did not produce sputum still showed an increase in F.E.V. during the early shift, though less marked than that of men with respiratory symptoms or who produced phlegm. The evidence suggests that a diurnal variation in lung function exists and should be taken into consideration both in epidemiological studies and when ventilatory capacity tests are used in periodic medical examinations.

Prognostic aspects of benzene poisoning.

Abstract: In 1955, a benzene mass-poisoning was detected in a shoe factory in Finland. One hundred and forty-seven persons were heavily exposed, and more than 100 had abnormal blood counts. One died and 10 required hospital treatment. This paper deals with a re-examination of the involved workers nine years later. One hundred and twenty-five persons attended for re-examination. Eight had died, two refused, and 11 could not be located. The possibility of death due to benzene poisoning having occurred among these persons was ruled out by checking the national death register. Each of the subjects underwent a haematological examination which included the haemoglobin value and the erythrocyte, reticulocyte, leucocyte, and thrombocyte counts. A differential count of the leucocytes was also made. A randomly chosen group of 86 persons served as a control group. The thrombocytes of the whole patient group and the erythrocytes of the men were significantly lower than those of the controls, whereas the leucocytes of the whole group and the erythrocytes of the women failed to show any statistical difference. In a multiple discriminant function analysis, considering all three counts at the same time, only the men differed slightly from the controls at the re-examination. The analysis also showed that the prognosis of the severe cases did not differ from that of the mild ones, provided the acute stage had been passed. Some illustrative case reports are added. One patient developed leukaemia after a latency of seven years, whereas most of the others—chosen because of grave symptoms in the initial stage—have recovered. The results are discussed from the point of view of prognosis.

Millworkers' asthma: allergic responses to the grain weevil (Sitophilus granarius).

Abstract: Two laboratory workers, who spent a considerable time each day handling grain infested by the grain weevil ( Sitophilus granarius ), developed allergic responses to this insect varying from rhinitis and pruritus to marked asthma. These findings suggested that weevil protein present in mill dust could result in sensitization in those exposed continuously. A pilot study was therefore undertaken on 75 volunteer millworkers to determine whether such sensitivity existed. A millworker was defined as anyone who worked in a flour mill or mill producing animal feed from mixed cereals, or who worked in grain-storing silos. Skin testing with weevil, mixed flour extracts, and a control was carried out on all 75 volunteers; 57% had a positive response to the weevil extract and 68% a positive response to the mixed flour extract. In a control group of 100 workers from two engineering firms matched for age and sex, 34% were positive to the weevil extract and 17% to mixed flour. From the initial 75 millworkers, 15 were selected for further study based on a positive skin response to the weevil and a history of a productive cough and chest tightness and wheezing when exposed to mill dust. The forced expiratory volume in one second (F.E.V. 1·0 ) was measured after control inhalations and after weevil and mixed flour inhalations. Significant reductions of 20% and 15·4% were found in two subjects after inhalation of weevil extract. In one case wheezing and cough developed. The changes in F.E.V. 1·0 were reversed after inhalation of a bronchodilator aerosol. Twenty-five of the control subjects with positive skin responses to the grain weevil were given similar provocation inhalations but none showed any significant change in F.E.V. 1·0 . This pilot study suggests that grain weevil sensitivity is an additional factor in millworkers9 asthma.

Hazy vision in amine plant operatives.

Abstract: The action of several amines suspected of causing hazy vision in humans has been studied in rabbit eyes. The disturbance appears to be brought about by a direct action of the amine on the cornea. It is recommended that workers exposed to this hazard should be warned that hazy vision is but a forerunner of a more serious conditon.

Resin dermatitis in a car factory.

Abstract: An outbreak of dermatitis in a car assembly factory is described; it affected 50 workers who handled rubber weatherstrips coated with an adhesive. The adhesive was found to contain para-tertiary butyl phenol (P.T.B.P.) formaldehyde resin. Of those patch tested 70% gave positive reactions to the adhesive and 65% to the resin. Improved methods of handling and personal protection succeeded in arresting the occurrence of dermatitis. Barrier creams gave no protection in these circumstances. The episode illustrates the different preventive control methods which have to be tried when dealing with a simple skin hazard which cannot be abolished.

Biliary Excretion of Lead in the Rat

Abstract: Studies have been made in the rat of the elimination of 210Pb in the bile after the intravenous injection of 100 μg of lead Four groups of rats were used: in two the bile was drained by cannulation of the bile duct, and in the other two the bile flow to the duodenum was interrupted by ligation or division of the bile duct The radioactivity of the bile, of the intestinal walls, and of the intestinal contents and faeces was determined The results showed that lead is eliminated from the liver mainly by the bile, thus excluding passage through the intestinal walls into the faeces as important under these conditions

Prevalence of Byssinosis and Dust Levels in Flax Preparers in Northern Ireland

Abstract: The association between the prevalence of both byssinosis and chronic bronchitis and the level of airborne dust was examined in workers in preparing departments in flax mills in Northern Ireland. A weak association between the dust level and byssinosis was found but not between the dust level and chronic bronchitis. It is suggested that the disparity of these associations may have arisen because the diagnosis of byssinosis, as in most recent published studies, was based on relatively acute and reversible symptoms which are more likely to be closely related to the current dust levels than the slowly developing symptoms on which the diagnosis of chronic bronchitis was based. Furthermore an association between chronic bronchitis and the dust levels is likely to be obscured to some extent by the effects of other non-industrial respiratory irritants such as tobacco smoke. Some hypotheses of the basic aetiology of byssinosis are discussed.

Trichloroethanol in Trichloroethylene Poisoning.

Abstract: Trichloroethylene and trichloroethanol were given intraperitoneally to guinea-pigs. Their effects were tested by measuring the threshold current intensity of electrical skin stimulation, the electrical excitability of the motor cerebral cortex, by recording and analysis of the electroencephalogram, and by electrocardiographic examination. The two compounds had similar effects on the nervous system and the heart, but trichloroethanol was the more effective by a factor of at least three. These results support the opinion of clinical investigators on the important role of trichloroethanol in the pathogenesis of trichloroethylene poisoning.

Relevance of Respiratory Symptoms and Signs to Ventilatory Capacity Changes after Exposure to Grain Dust and Phosphate Rock Dust

Abstract: Ventilatory capacity was measured before and after exposure to high concentrations of wheat dust in 24 men, 18 of whom were similarly studied while working with calcium phosphate rock. Changes in ventilatory capacity were examined in relation to respiratory symptoms as commonly elicited in occupational surveys, and to the presence or absence of a productive cough on request and under observation. A significant decrease in the forced expiratory volume at one second was observed within half an hour of beginning work in the wheat dust, and this decrease was maintained throughout the work shift. A smaller significant decrease was found on exposure to phosphate rock over several hours, no significant change occurring within the first half-hour. Greater or more consistent decreases were recorded in those men who gave a history of persistent cough and sputum, and more particularly in those who had a productive cough on request, than in those without these features. A history of symptoms on exposure failed to define a group showing any more severe ventilatory reaction on exposure to wheat dust than the average. Some of the factors influencing the history of symptoms in occupational populations are reviewed, and the advantage of an objective sign, as provided by a deliberate cough, is indicated in defining an `abnormal9 group within such a population.

Acute Toxicity and Skin Irritant Properties of Sulfolane

Abstract: Sulfolane is a useful industrial solvent. The oral LD50 values were: rats, 1·7 to 2·7 g./kg.; mice, 1·9 to 2·5 g./kg., all deaths taking place within 24 hours. Rats showed no effects after 3·8 g./kg. had been applied to the skin. The compound did not irritate or sensitize the skins of guinea-pigs or rabbits and, undiluted, was almost without action on the eyes of rabbits.

Acute intoxication from antimony trichloride.

Abstract: Seven men were accidentally exposed to the fume of antimony trichloride. Their symptoms included not only the well-recognized upper respiratory irritation from hydrochloric acid but, in five of the men, an additional, slightly delayed onset of gastro-intestinal disturbance including abdominal pain and persistent anorexia. Urine antimony estimations revealed a concentration in excess of 1 mg./litre in these five men. Environmental measurements suggest that they were briefly exposed to air containing up to 146 mg. hydrochloric acid and 73 mg. antimony per m.3 expressed as the metal. These findings are compared with other reports on chronic antimony intoxication. No report could be found in recent literature about acute intoxication from antimony trichloride.

Urinary Screening Tests to Detect Excessive Lead Absorption

Abstract: The biological variation encountered in spot urine samples was assessed by collecting six sets of serial urine specimens from five men. The lead, coproporphyrin, and creatinine contents of each specimen were determined and the specific gravity was measured. It is found that as the mean concentration of the metabolite rises so the variability of the individual values increases. The scatter of the concentrations is not significantly different from that found in the rates of excretion. Adjustment of the figures to either a constant specific gravity or creatinine concentration increased the scatter. The effect of the diurnal cycle on the variability is negligible as the spread of the combined results is uniform over the 24-hour period. The results of spot urine samples must be considered collectively before they can indicate the mean excretion level. Twenty-four-hour urine samples were obtained from 23 lead-intoxicated men before and throughout their treatment with chelating agents. The initial excretion of lead during intravenous infusion of disodium calcium ethylenediaminetetra-acetate (first Pb EDTA) and the weight of lead excreted as the complex, before the coproporphyrin excretion falls to a normal level (less than 100 μ.g per day), termed the `excess9 lead, are used as objective measures of the lead absorption. These two indices are linearly related to the pretreatment urinary levels of lead and coproporphyrin, regardless of whether the results are expressed in μg. per litre or μg. per day. Due to the environment having an effect on the urinary concentrations it is concluded that in general the weight of metabolite excreted in the 24-hour period possibly provides the more reliable guide to the lead absorption of the individual.