430 C. F. Lorenc, headmaster, Meadway School, Reading, Mrs J. Smart, school-nurse, Meadway School, Reading, and the many volunteers who agreed either to be Schick tested or to provide a blood sample, for their help. Requests for reprints should be addressed to Dr F. W. Sheffield, Division of Bacterial Products, National Institute for Biological Standards and Control, Holly Hill, Hampstead, London NW3 6RB. -

REFERENCES 1. Placido de Sousa, C., Evans, D. G. Br. J. exp. Path. 1957, 38, 644. 2. Mivamura, K., Nishio, S., Ito, A., Murato, R., Kono, R. J. biol. Standard.

1974, 2, 189. 3. Wilson, G. S., Miles, A. A. Principles of Bacteriology, Virology and Immunity; p. 1673 and 1677. London, 1975. 4. Hartley, P., Tulloch, W. J., Anderson, M., et al. Spec. Rep. Ser. med. Res. Coun. 1950, no. 272, iv. 5. Smith, J. W. G. in Proceedings of an International Conference on the Application of Vaccines against Viral, Rickettsial, and Bacterial Diseases of Man. Pan American Health Organization Scientific Publication, no. 226. 316, Washington, D.C. 1971. 6. Scheibel, I., Bentzon, M. W., Christensen, P. E., Biering, A. Acta path. microbiol. scand. 1966, 67, 38.

Occupational Health RESPIRATORY HAZARDS FROM PAPAIN M. L. H. FLINDT

Department of Occupational Health, University of Manchester, Stopford Building, Oxford Road, Manchester M13 9PT

Late-onset asthma occurred in a nonatopic worker in a factory where papain was powder packed. The patient had had 3 attacks of asthma since first being exposed to atmospheric papain dust. He gave a positive immediate reaction to skin-prick tests with solutions of papain which were appreciably weaker than solutions which caused no reaction in unexposed individuals. These results, together with his history and the fact that symptoms stopped when he was not exposed to papain, suggest that he had extrinsic allergic asthma caused by sensitisation to papain. Shortly after re-exposure to papain a worker in another factory died during an attack of asthma. Measures to prevent the inhalation of papain dust must be taken in factories where papain is handled, not only to avoid the proteolytic effects of the material but also to prevent workers from becoming sensitised.

Summary

significant occupational dust exposure, had employed’for 3 Zyears in a factory where papain powder was occasionally blended and packed for sale as atopy

or

of

been

tenderiser. He was a fork-lift truck driver in the storage warehouse adjacent to the packing room, and sometimes helped in the packing room. On four previous occasions when papain was being packed he had not experienced symptoms, but in January, 1976, he became short of breath 1hours after starting work in the warehouse while papain tenderiser was being hand-packed in the adjacent packing room. He sought relief in fresh air for 20 minutes, but on resuming work, his symptoms became severe, dyspnoea being most pronounced on expiration and associated with wheezing. His doctor prescribed a bronchodilator inhaler, which gave some relief, and antihistamine tablets. His symptoms were worst in the first 2 days of illness lessening after 4 days. He was absent from work for a fortnight. When papain was again packaged about two months later, he experienced chest symptoms half an hour after starting work in the warehouse while the tenderiser was being hand-packed in the next room. He was sent home and was off work for a fortnight. A third episode of breathlessness occurred early one Monday after he had last worked in the warehouse on the previous Saturday while papain was being machine-packed in the adjacent room. He could not go to work and was seen twice that day by his doctor. He was awake all night with dyspnoea and, next day, started a course of corticosteroid tablets. He was off work for five weeks. Subsequently he went outside the factory on the rare occasions when papain was packed and, when I first saw him 3 months later in July, 1976, he had discontinued corticosteroid tablets but was still using rimiterol and beclomethasone inhalers 4 times a day. He was sympa meat

TABLE I-LUNG-FUNCTION

RESULTS*

INTRODUCTION

PREPARATIONS of papain, containing proteases derived from the latex of papaya (Carica papaya, paw paw fruit), are increasingly used in biochemical laboratories and for tenderising meat and clarifying beer and other beverages. Spray-dried preparations, which are purer and more active and in fine-powder form, are now being

prepared by tropical producer-countries. The potential hazards of handling such preparations are not yet widely recognised.l One of the hazards is illustrated by the following case history. A

man

aged 45,

with

no

history of

*All 3 examinations were:: de at about midday. at 50’/f. and 75% Of F.v.c. recorded examination. B.T.P.s.=body temperature and pressure saturated.

tFlow-rates measured

CASE HISTORY

chest illness

or

at

the minal

431 not tried doing without his inhalers. had He given up cigarette smoking a year before. His heart were clinically normal’ as were chest and chest radiographs, apart from minimum blunting of the left costophrenic angle as if by pleural reaction; and lungfunction test results (table I) were within normal limits.z3 Sputum was unobtainable, but there was no blood eosinophilia. Serum otj-antitrypsin was 2-5 g/1 (70% of average normal). Serum IgE and IgM were raised (see table n), and electrophoresis showed increases in Cl.2 and y globulins. Skin-prick tests4 were negative to Bencard solutions of Aspergillus fumigatus 10%, Dermatophagoides pter-

tom-free but had

TABLE II-SERUM IMMUNOGLOBULINS IN A WORKER EXPOSED TO

PAPAIN

*Radial immunodiffusion test (Hoechst), Biochemistry Laboratory, Manchester Royal Infirmary. tPaper radioimmunosorbent test (’PRIST’, Pharmacia Diagnostics), Immunology Laboratory, Manchester Royal Infirmary. ,

onyssinus 1.2%, and group-B2 (pollens) grasses 2.5%. was a positive immediate reaction (7 mm weal and 4 cm flare by 20 min) to papain pure B.P.C. (KochLight) 1 mg/ml in carbol saline, but no late or delayed reaction. This papain solution was 10 times weaker than one which had caused no reaction in both atopic and non-atopic controls who had not been exposed to papain. Precipitins were demonstrated when his serum was tested against papain in Ouchterlony agar-gel double-

had had no further severe attacks of asthma, although he still used his inhaler occasionally for mild attacks of chest tightness and wheezing, especially in damp cold weather. He continued to avoid the packing room, and to work outside when papain was being packed. His chest and heart were clinically normal, as were chest radiographs. There was no blood eosinophilia. Serum«1-antitrypsin was 2.5 g/1 (70% of average normal). Serum-IgE had now fallen to within the normal range for non-atopic patients, other immunoglobulin concentrations being somewhat higher than at the initial examination (table II). Lung-function tests (table I) showed normal gas transfer, but the F.E,V’l and F.v.c. remained lower than at the first examination, although they had improved since the interim examination. Spirometric tests at the factory 6 days later gave similar results. On each occasion salbutamol inhalation led to an increase in F.E.V.1 of about 11% and in F.v.c. of about 7%, which brought the readings close to those obtained at the initial examination. Skin-prick tests to the three Bencard solutions of common allergens were again negative. There were positive immediate reactions (measured at 20 minutes) to: papain pure B.P.C. (Koch-Light) 1 mg/ml (8 mm weal, 3 cm flare), and 0.11 mg/ml (6 mm weal, 2 cm flare); and to high-activity papain (papain PI, Powell and Scholefield) 1 mg/ml (10 mm weal, 3.5cm flare), and 0.11 mg/ml (10 mm weal, 3 cm flare). There were no late or delayed reactions. The weaker solutions of both preparations of papain were 100 times more dilute than solutions which had caused no reaction in both atopic and non-atopic controls.

There

diffusion tests. However, as in the case of the Bacillzis subtilis protease used for enzyme detergents,S there was a similar reaction with the serum of control individuals. It seems likely that, as was found with B. subtilis protease,6 these precipitins are due to anti-protease activity rather than specific allergy.

Lung-function

the factory, 9 months later, he had last used a salbutamol in forced expiratory volume in 1 forced vital capacity (F.v.c.), the or greater than 2 standard devia-

tests at

and 20 hours after

inhaler, showed falls

second (F.E.V.1) and results being close to tions below predicted values2·3

(table i). Maximum exconsiderably reduced, but this may have been related to the large reduction of the F.E.V., and F.v.c. Total lung capacity (T.L.C.) fell by 350 ml and, because the fall in vital capacity was proportionally greater, the residual volume (R.v.) and R.V./T.L.c. ratio was substantially raised. These findings may have indicated increased airway muscle tone either as a residual effect of his earlier illness or perhaps because the environment was not free of papain dust. However, a test for reversibility was not included. At follow-up, 15 months after the initial examination and 6 months after the interim factory examination, he piratory flow-rates

were

DISCUSSION

I believe that this non-atopic man had become sensitised to papain after early exposure(s) and was having attacks of extrinsic allergic asthma as a result of breathing the dust on subsequent occasions. The skin tests and history suggest that his asthma was due to a reaginmediated type-I reactionalthough other mechanisms may have contributed to his third, delayed, attack. Airborne dust levels of papain in this factory were appreciably in excess of the ceiling value of 0.00006 mg/m3 proposed for another protease, subtilisin, used in enzyme

detergents.8 Implications I am investigating skin-prick reactions in workers in factories handling papain. Positive skin-prick reactions to papain have been obtained in both atopic and nonatopic individuals, as have histories of asthma attacks and/or nasal symptoms after use of the material in packing rooms and laboratories. These are not isolated phenomena in unduly sensitive or heavily exposed individuals, and they have also been experienced by fellow workers in adjacent rooms. I was prompted to publish this case-report, and the preliminary findings of the factory survey, by an inquest9 into the death of a 35-year-old man who, having ceased to have attacks of asthma at the age of 14, started to have them again a year after he began work in a factory in which papain powder was occasionally used for hydrolysis of proteins. In December, 1976, 6 months after this susceptibility to asthma developed, he

432

shortly after a workmate, about 30 (10 metres) away, had tipped 1.25 kg of papain powder (containing 80 parts of crude and 20 parts of high-activity papain) into protein-digest pans. He had feet

a severe

attack

obtained no relief from a salbutamol inhaler and died half an hour later. The inhaler had been supplied by his doctor but, unfortunately, the apparent association between papain and his illness had not been reported, and his employers were not aware of his condition before. the fatal episode. Total serum-IgE was raised, being 2600 international units per ml (normal upper level 840 i.u./ml, radioimmunosorbent test; Protein Reference Unit, Westminster Hospital, London). Post-mortem findings were consistent with an acute allergic reaction, death being due to anaphylactic shock. No other cause of death was found.

Guineapigs apparently become sensitised after a first intratracheal instillation of papain, and some die, with findings characteristic of anaphylactic shock when a second dose is injected.10 My findings in the patient described earlier show that such sensitisation can also occur in, man. Two cases of asthma believed to be due to inhalation of papain powder were reported by Milne and Brand." Evidence of specificity was sought by rubbing papain paste into a skin scratch. The patients’ reactions demonstrated that they had almost certainly become sensitised to papain; controls did not react to scratch tests with the paste. Both their patients were atopic. My patient, and some of the others I have subsequently skin-prick tested and found to be sensitised, were not atopic. Asthma and urticaria have been described in workers handling papain in the pharmaceutical industry, these ill-effects being prevented by strict

safety precautions. 12 Animal experiments-

.

have demonstrated ill-effects other than asthma due to sensitisation. Direct or indirect proteolytic action is probably the most serious of these other effects of inhalation. 13 Experimental emphysema was produced within 6 h of a single intratracheal instillation of 1 mg of papain into guineapigs or ratsl4 and in golden hamsters which had inhaled an aerosol of 3% papain for 4 h. 15 Initially it was feared that proteolytic enzymes in some detergents might cause emphysema in exposed workers. Fortunately, these fears have not been fully realised,6perhaps because efforts were made to control the hazard. However, Gandevia and Mitchell found loss of elastic recoil in the lungs in some exposed individuals, 16 which they attributed to emphysema. Papain is probably a more potent cause of emphysema than the subtilopeptidase used in the detergent industry. Inhalation of either the subtilopeptidase or papain can cause hemorrhage within the respiratory tract of laboratory animals, which sometimes proves fatal; emphysema developed in animals which recovered from the acute effects of papain but not in those that had received

subtilopeptidase.17 Thus if papain did

have the sensitisation potential described its use would still demand considerable precautions. My current survey of factories using papain seeks to show whether there is any evidence of early emphysema or other permanent pulmonary damage in exposed workers. Smokers and those with low serum-at antitrypsin may be at greater risk of emphysema. However, in view of the allergic effects described, initiation not

of preventive action should not depend on the results of this or other surveys being known. I believe that rigorous measures to eliminate the risk of sensitisation, and illness developing as a result of sensitisation, will automatically prevent other biological consequences of

inhalation. Prevention

Principles of prevention resemble those applied in the soap and detergent industry’8 to the hazard from B. subtilis proteinase.5 With papain, there is perhaps more scope for use of the material, appropriately stabilised, in liquid form. Preparations of papain powder sold to domestic consumers are relatively dilute, and are often made less dusty by oil-treatment. Where such precautions are taken, or the material is sold as a liquid or in large granules which cannot readily become airborne, the risk to the consumer is likely to be appreciably less than that to workers processing the material in the primary producer countries or who are associated with its handling in importing countries. However, it would be advisable to test dry-powder products for "dust-liberating potential" and, when indicated, to modify the method of presentation. Such a test18 was found useful with the protease used in enzyme detergents. Sakula’9 reported asthma due to sensitisation to pancreatic enzymes in a mother who used these enzymes in powder form as a dietary supplement for her two young children with cystic fibrosis. This indicates that gross atmospheric contamination by digestive enzymes is not necessary to initiate sensitisation quences. Therefore great

marketing

a

or to

care

proved allergen

in

contribute to its conseis needed to avoid

a

potentially respirable

form. I thank Dr D. L. Caldwell, Dr Kenneth Cowen, and Dr I. J. Harris confirming details on the first patient, and Dr David Chinn (supported by M. R. C. grant number SPG975/421) for the lung function tests. I also thank Mr J. G. Jones, Mr Alan Hayball, Mr T. A. Partington, Mr J. Seneviratne, and Mr P. Vanderzeil for their cooperation and Dr Elizabeth Husband and Mr Eric Bridson for supplementing the published details on the fatal episode.

for

REFERENCES

1. Fletcher, D. C., J. Am. med. Ass. 1976, 236, 970. 2. Cotes, J. E. Lung Function Assessment and Application in Medicine. p.

380.

Oxford, 1975. 3. Bass, H. Chest, 1973, 63, 171. 4. Pepys, J. in Clinical Aspects of Immunology. (edited by P. G. H. Gell and R. R. A. Coombs); p. 192. Oxford, 1968. 5. Flindt, M. L. H. Lancet, 1969, i, 1177. 6. Soap and Detergent Industry Association, Thorax, 1976,31,621. 7. Gell, P. G. H., Coombs, R. R. A. (editors) Clinical Aspects of Immunology; p. 580. Oxford, 1968. 8. American Conference of Governmental Industrial Hygienists, Documentation of the Threshold Limit Values for Substances in Work Room Air. Cincinnati, Ohio, 1976, Value adopted by Health and Safety Executive, Guidance Notes EH 15/76, H.M. Stationery Office 1976. 9. Basingstoke Gazette, Feb. 18, 1977, p. 1. 10. Gross, P., deTreville, R., Babyak, M. A., Karschak, M., Tolker, E. Archs

envir Hlth, 1968, 16, 51 J. ind. Med. 1975, 32, 302. 1969, 60, 732. Cited by Keatinge, G. F. Abstr. Hyg. 1970, 45, 740. 13. Johnson, D , Travis, J. Biochem J. 1977, 163, 639. 14. Gross, P., Pfitzer, Emil, A., Tolker, E., Babyak, M. A., Karschak, M. Archs envir. Hlth, 1965, 11, 50. 15. Goldring, I., Greenburg, L., Ratner, I. ibid. 1968, 16, 59. 16. Gandevia, B., Mitchell, C. Med. J. Aust. 1971, i, 1031. 17. Goldring, I. P., Ratner, I. M., Greenburg, L. Science, 1970, 170, 73. 18. Soap and Detergent Industry Association, Ann. occup. Hyg. 1971, 14, 71. 19. Sakula, A. Br. J. Dis. Chest, 1977,71, 295. 11. Milne, J., Brand, S. Br. 12. Nava, C. Medna Lav.

Respiratory hazards from papain.

430 C. F. Lorenc, headmaster, Meadway School, Reading, Mrs J. Smart, school-nurse, Meadway School, Reading, and the many volunteers who agreed either...
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