During the outbreak of poliomyelitis which occurred in Toronto during the months of August, September, and October, 1937, a study (1) was conducted to furnish information concerning the possible prophylactic value of the zinc sulfate nasal spray, the use of which was suggested by the findings of Schultz and Gebhardt,(2) and Peet, Echols, and Richter. (3) Observations were made on a group of 4,713 children, aged 3 to 10 years, who received two sprayings with an interval between the sprayings of ten to twelve days, and 520 additional children who received only one spraying. The spraying was conducted in special clinics by otolaryngologists. Schultz and Gebhardt, and Peet and his collaborators expressed their belief that the satisfactory covering of the olfactory area was indicated by the loss of the sense of smell. From the observations made in the Toronto study, it would appear that not more than 25 per cent of the children sprayed developed anosmia (temporary). Inquiries have indicated that very few, if any, of the children who were sprayed in the special clinics reported subsequently to the various hospital clinics complaining of persisting anosmia. It is to be remembered that this age group consisted of children of from 3 to 10 years of age.

Through the cooperation of the otolaryngologists of the various city hospitals, reports were supplied concerning the persons sprayed by them in their private practice. Data were kindly furnished regarding age and the number of sprayings. Information wasalso supplied concerning the presence of anosmia at the end of the tow months, with or without disturbance of the sense of taste, and similar information at the end of six months. Reports were received from thirty-two otolaryngologists. Statements were not made in their reports concerning the method of determining the loss of the sense of smell or the disturbance of the sense of taste. The number recorded having anosmia with or without disturbance of the sense of taste at the end of the two months was thirty-six and the number at the end of six months was fifty-two, indicating that a number of patients did not consult their otolaryngologists until several months had elapsed. These data, arranged in age groups, are presented in Table I; in Table II, data are presented, arranged according the number of sprayings.

Although data were not available regarding the total number of persons sprayed by the various otolaryngologists, the total number probably did not exceed 5,000. That it is not too conservative an estimate is indicated by the fact that records of only 741 children receiving two sprayings in private practice were received from the otolaryngologists of the city for inclusion in the report of the original study. The findings as presented in Table I indicate that the complaint of persistent anosmia occurred more frequently in the older age groups. Although it is not possible to state the methods of testing the sense of smell used by the various otolaryngologists, there can be little doubt that these patients at the end of six months had definite complaints of disturbance of the sense of smell and, in many instances, of taste. It will be noted from Table I that only five children less than 10 years of age were reported by the group of otolaryngologists, in their private practice, as having anosmia at the end of two months and only one at the end of six months. These findings are in accord with the opinion of the attending otolaryngologists that few if any, of the children who received the nasal spraying in the special clinics subsequently suffered from a continuing disturbance of the sense of smell. Persisting disturbance of taste and smell was noted in eleven cases (Table II), in which the patients received only one spraying, and in thirty-nine who received two sprayings. The clinical reports relating to the fifty-two patients, who at the end of six months had disturbances of the sense of smell and taste, include patients with marked loss of the sense of smell as well as others in whom the sense of smell is returning. Some complained of unpleasant odors and others of a distorted sense of smell. Disturbances of taste were frequently associated with disturbances of smell (table I).

DISCUSSION

Schultz and Gebhardt based their belief that the application of 1 per cent zinc sulfate with 0.5 per cent pontocaine, in the small amounts required to cover the olfactory area, would not produce any undesirable or harmful effects on the finding that no noteworthy gross or microscopic changes were found in the nasal mucous membranes of monkeys treated repeatedly with zinc sulfate, other than a mild grade of inflammation. Peet and his collaborators recorded anosmia following the application of the spray in a group of medical students but found that the sense of smell returned within one or two weeks. Dr. Peet (4) reported that all children sprayed by him and by his associates in Michigan last summer had been re-examined, and in every one the sense of smell had returned. In some adults, however, the sense of smell did not return to normal for three months or even longer.

The persisting disturbance of sense of smell and taste in certain individuals, after a period of six months, is difficult to explain on the basis of a persisting inflammation of the olfactory mucous membrane, causing a mechanical blocking of the olfactory area. A study of the changes in the olfactory mucous membrane following the instillation of zinc sulfate in rats, (5) and similar observations made in ferrets (6) suggest that the effect of a one per cent solution of zinc sulfate on the mucous membrane of human beings should be carefully studied to determine if the persisting disturbance of smell and taste be due to injury of the olfactory area.

REFERENCES

1. Tiedall, F.F., Brown, Ala, Defries, R.D., Ross, M.A., and Sellers, A.H.: Canad. Publ. Health J. 88:532, 1937

2. Schultz, E.W., and Gebhardt, L.P.: J.A.M.A. 108:3294, 1937.

3. Peet, M.M., Echols, D.H., and Richter, H.J.: J.A.M.A. 108: 2184, 1937.

4. Peet, M.M.: Personal communication, University of Michigan, Ann Arbor, Mich.

5. Smith, C. G.: Personal communication, Department of Anatomy, University of Toronto.

6. Stuart-Harris, O.H. Personal communication, Rockefeller Institute for Medical Research, New York.