Commentary

SOME THOUGHTS ON DIEEERENCES IN BLACK AND WHITE SKIN CHARLES J.

MCDONALD, M.D.

From the Sub-Section of Dermatology, Division of Bio-Med Sciences, Brown University College of Medicine, and the Department of Medicine, Roger Williams General Hospital, Providence, Rhode Island

It is my belief that there is no other organ or body system than the skin of which so much misinformation has been disseminated and so many misconceptions perpetuated about its anatomic biochemical and physiologic constitution. These misconceptions have long nurtured myths regarding racial superiority and the incidence and/or prevalence of diseases in Caucasians and Negroes. As a dermatologist, 1 contend that in any approach to the discussion of dermatological problems in skin of Negroes, it must first be established that there are skin diseases or cutaneous reaction patterns that are peculiar to Negroes. My extensive review of the English literature has shown that meaningful supporting scientific data on inherent racial peculiarities in skin of Negroes are very limited or, in most cases, nonexistent. Anyone making generalizations about race and disease must consider the diverse population groups of which each race is comprised. I suggest caution in accepting as factual the concept that race and ethnic origin alone exert strong positive and negative influences on disease type, prevalence and severity. Cenetic, environmental, economic, social and occupational factors, as well as the availability of adequate medical care, exert stronger influences on disease prevalence than do racial factors.

The cutaneous appendages (the eccrine and apocrine sweat glands, the hair and the sebaceous glands), their structure and function, are second only to the color of the skin in evoking unscientific dissertations and myths of racial superiority, inferiority, disease incidence and susceptibility to disease. Therefore, 1 propose to discuss some brief but significant facts about the anatomy and the physiology of the cutaneous appendages which do not support their often-used roles as instruments of proponents of racial inferiority or superiority. Structure and Function The structure and the function of the eccrine sweat glands have often been used in racial epithets to support ideas of racial superiority, inferiority or differences. A saying such as "sweating like a nigger" is but one exatTiple. It implies that Negroes tend to sweat more profusely than other racial groups. If we look closely at the available scientific data, we find that the eccrine sweat glands are distributed over the 427

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entire body surface of man. There are from 2 to 3 million glands in the skin of each human being. Adaptive as well as individual factors are mostly responsible for the wide variations in the number of glands per individual.' For example, Kawahata and Sakamoto- have shown that the total number of sweat glands per unit surface area in the skin of Japanese born in Japan who migrate to the tropics is the same as in Japanese born in Japan who continue to live in Japan. However, persons of Japanese descent who are born in the tropics and live in the tropics have a significantly larger number of sweat glands per unit area than either of the 2 groups. These data tend to support my contention that environmental (climactic) factors rather than racial are mostly responsible for differences in the number of eccrine sweat glands. Additionally, the studies of Herrmann and colleagues^ have shown that there is little or no difference between the sweating ability of Negroes and Caucasians. Rebel and Kirk-* state emphatically "that no clear correlations have been observed between sweat pattern type and somatic type or ethnic background." The amount of sweat produced at a given temperature relates to acclimatization (successive exposure) to heat rather than racially determined anatomical or physiological factors. A possible relationship between pigmentation and increased sweating due to the increased heat absorption ability of dark as opposed to light skin has been proposed; however, this relationship is purely conjectural without supporting scientific data and should not be thought of as being factual. Cross racial differences in distribution and numbers of apocrine sweat glands have been described by proponents of

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racial superiority and inferiority. Apocrine glands have been described as being more numerous in Negroes.•"' A rationale for their use in arguments about racial superiority is as follows: apocrine glands occur over the entire body in all mammals except in man, where they are absent or rudimentary in all areas except the axillae, groin, pubic region, around the umbilicus and in the external auditory canal. If Negroes are shown to have more apocrine glands that are more widely distributed than Caucasians, certainly they are then more like their mammalian ancestors than Caucasians are and thus are more inferior human beings. It has been demonstrated that individual rather than racial variations in distribution and size of apocrine glands is so great that data on such variations in size and number cannot be used for purposes of racial differentiation.'' Sebaceous glands in Negroes have been described as being larger and more active physiologically than those in Caucasians. However, sexual, age and regional influences on variations in size make it difficult for one to defend this characterization. The only truly scientific data on sebaceous gland activity come from the studies of Nicolaides and Rothman.' They have reported significant differences in the thickness of the oily film on the hair of Negroes and Caucasians, which may in some part be related to sebaceous gland function. Negroes have, on the average, 60 to 70% more hair fat than Caucasians. The physiological significance, if any, of this finding has yet to be demonstrated. Disease States Moving from the basic biology of the skin to diseases of the skin and other organ systems, the venereal diseases may

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be classified as shining examples of diseases thought to be more or less confined to the black-skinned population. In the early half of the 20th century and the latter part of the 19th, it was generally believed that venereal diseases occurred with much greater frequency in Negroes than in Caucasians. It was also believed that manifestations of venereal diseases and their sequelae differed in Negroes and Caucasians. Recent public health information tends to refute or at least make less valid these beliefs and assumptions. For example, surveys conducted by the American Social Health Association in 1962 and 1968, and subsequently detailed by Fleming and others, on the reporting practices of private physicians have shown that only 10 to 30% of the venereal diseases treated by private physicians are reported to appropriate public health facilities.'^^ '^ All patients seen and treated in venereal disease and public health clinics are automatically reported. Negro patients, because of economic necessity and medical habits, nearly always attend venereal disease and public health clinics where their cases of venereal disease are promptly reported. Most Caucasian patients are treated in private physicians' offices: their cases are not reported. It is of great interest to note that in 19601962 National Health Examination survey, serological reactivity rates for syphilis in representative samples of Negroes and Caucasians did not support the data accumulated on reporting rates'"; the two races had almost equal serological reactivity rates indicating equal frequency of infection with syphilis. In considering disease manifestations, at least one report among the many from the now-infamous "Tuskegee study" showed that some form of central nervous system syphilis was found in a sig-

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nificant number of Negro patients." In fact, the percentage of patients manifesting central nervous system syphilis in the early phases of the Tuskegee study exceeded the percentage reported in Bruusgaard's Oslo study.'^ Before this report, central nervous system syphilis was thought to occur rarely in Negroes but was thought to be a frequent occurrence in Caucasians. Instead, cardiovascular disease was thought to be frequently encountered in Negroes and rarely in Caucasians. Peters and associates,'-^ reporting on autopsy material from the Tuskegee study, noted that the primary cause of death in 30% of the infected, untreated group of Negro patients could be traced to syphilitic involvement of the cardiovascular or central nervous system. These 2 studies are among many that should dispel the belief that incidence, manifestations and sequelae of venereal diseases differ in Negro and Caucasian patients. It is possible to extend this discussion to include other diseases and/or derangements in the normal structure and function of the skin, but 1 believe the significant point has been made.

Conclusions I wish to emphasize that all diseases and disorders of the skin and its appendages which occur in white skin also occur in black skin and vice versa. Therefore, I urge each physician to approach the diagnosis and treatment of diseases of the skin in Negroes in much the same manner as in Caucasians. The physician has to be aware of certain minor racial differences in secondary skin responses to disease, viz., the accentuation or the inapparent appearance of many so-called normal and abnormal responses of the skin to disease. But in most situations, the expected responses to disease are

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present and rarely do they necessitate different diagnostic and therapeutic approaches to skin disorders in black as opposed to white skin. References 1. Szabo, G., Tbe number of eccrine sweat glands in buman skin. Cbapter 1. In Advances in Biology of Skin. Vol. III. Edited by Montagna, W., Ellis, R. A., and Silver, A. New York, Pergamon Press, 1962, pp. 1-5. 2. Kawabata, A., and Saramoto, A., Some observations on sweating of tbe Aino. Jap. J. Physiol. 2:166, 1951. 3. Herrmann, F., Prose, P. H., and Sulzberger, W. B., Studies on sweating. V. Studies of quantity and distribution of thermogenic sweat delivery to the skin. J. Invest. Dermatol. 18:71, 1952. 4. Rebel, G., and Kirk, D., Patterns of eccrine sweating in the buman axilla. Cbapter VII. In Advanres in Biology of Skin. Vol. III. Edited bv Monlagna, W., Ellis, R. A., and Silver, A. New York, Pergamon Press, 1962, pp. 108-126. 5. Homma, Fi., On apocrine sweat glands in white and Negro men and women. Bull. Johns Hopkins Hosp. 38:365, 1926.

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6. Wollard, H. H., The cutaneous glands of man. J. Anat. 64:415, 1930. 7. Nicolaides, N., and Rothman, S., Studies on the cbemical composition of human hair fat. II. The overall composition witb regard to age, sex, and race. J. Invest. Dermatol. 21:9, 1952. 8. Fleming, W. L., Brown, W. J., Donohue, J. R., and Braningan, P. W., National survey of venereal diseases treated by physicians in 1968. JAMA 211:1827, 1970. 9. McKenzie-Pollock, J. S., Physician reporting of venereal disease in the United States. Br. J. Vener. Dis. 46:114, 1970. 10. Findings on the serologic test for syphilis in adults. United States 1960-62. National Center for Health Statistics, Public Health Service, Department of Health Education and Welfare, Series II, No. 9, June 1955. 11 Vonderlebr, R. A., et al.. Untreated sypbilis in the male Negro. J. Venereol. Dis. Inform. 17:260, 1936. 12. Gjestland, T., The Oslo study of untreated syphilis. An epidemiologic investigation of the natural course of the sypbilitic infection based upon a re-study of tbe Boeck-Bruusgaard material. Acta Derma. Venereol. (Suppl. 34) 15:1, 1955. 13. Peters, J. J., et al.. Untreated sypbilis in tbe male Negro: Patbologic findings in sypbilitic and nonsypbilitic patients. J. Cbronic Dis. 1:127, 1955.

Sex Education One critical issue in family life is the delicate one of contraceptive education for young people. On this c|uestion a distinction needs to be made between knowledge of contraception on the one hand and education in their responsible use on the other. When a high school students asks, as one did recently, "Is oral or anal intercourse the best way to avoid pregnancy?" parent or doctor cannot pretend that contraception does not exist. Behind the words lurks another question, of course, which the sensitive counselor recognizes: How do I act responsibly? To the contraceptive question, however, a truthful answer must be given. Avoidance of conception is a fact of life which adolescents have a right to know.—Springer, R. H.: Marriage, the Family, and Sex—A Roman Catholic View. Perspect' Biol. Med. 19:194, 1976.

Some thoughts on differences in black and white skin.

Commentary SOME THOUGHTS ON DIEEERENCES IN BLACK AND WHITE SKIN CHARLES J. MCDONALD, M.D. From the Sub-Section of Dermatology, Division of Bio-Med...
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