Relative efficiency of pigment and horny layer thickness in protecting the skin of Europeans and Africans against solar ultraviolet radiation*

Thomson, M. L.

doi:10.1113/jphysiol.1955.sp005252

Cited by 136 publications

(38 citation statements)

References 10 publications

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“…Even though the stratum corneum is equally thick in black and white skin [2,3] , Weigland et al [4] demonstrated that the stratum corneum of the African-American population contains more cell layers. On average 20 cell layers were observed in African-Americans versus 16 layers in Whites.…”

Section: Introductionmentioning

confidence: 99%

Ethnic Variation in Vellus Hair Follicle Size and Distribution

Mangelsdorf

Otberg²,

Maibach³

et al. 2006

Skin Pharmacol Physiol

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It is a given fact that hair follicles play an important role in the penetration process of topically applied drugs and cosmetics. Since exact knowledge of the potential follicular reservoir is essential for understanding and calculating the penetration process, this knowledge may indeed help to optimize the development of topically applied drugs and cosmetic products. We know that variability in skin properties exists among the human population, but it is the deciphering and quantification of these differences that may help to explain racial disparities in dermatological disorders and provide a basic approach for treatment and prevention. Data pertaining to structural and functional differences within ethnic skin types (reviewed in this paper) support the assumption that hair follicles in the various skin types are not equal. Thus, the need to investigate follicular morphology in non-Caucasian skin types becomes more than apparent. The aim of the present study was to determine the potential reservoir of vellus hair follicles in non-Caucasian skin types in order to estimate their contribution to the penetration of topically applied substances. Cyanoacrylate skin surface biopsies were taken from seven body sites of Asians and African-Americans. To determine the follicular reservoir, the samples were evaluated under the light microscope. Follicular parameters were measured with the help of a digital imaging software program. In the evaluation and comparison of the results with those of Caucasians, significant differences were detected. Compared with Whites, follicular density on the forehead is significantly lower in Asians and African-Americans. Smaller values were detected for volume, surface, follicular orifice and hair shaft diameter on the thigh and in calf regions in Asians and African-Americans. Furthermore, the follicular reservoir, characterized by follicular volume, is generally higher in Caucasians. In comparison to African-Americans, larger follicular volumes on the forehead, back and on the upper arm were determined in Asians. The fairly similar density in these sites revealed that Asians have a higher follicular reservoir in these sites. Due to significant ethnic differences in the follicular reservoir, particularly on the calf and forehead, prospective skin absorption experiments need to be performed on different skin types in order to be representative. Likewise, the development of topically applied drugs should take place under adequate consideration of ethnic differences in skin physiology.

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Section: Introductionmentioning

confidence: 99%

Ethnic Variation in Vellus Hair Follicle Size and Distribution

Mangelsdorf

Otberg²,

Maibach³

et al. 2006

Skin Pharmacol Physiol

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“…skin or deep tissue). There is significant reflection by rat hair and skin and human skin [1,22], A good deal of light scatter can be expected in the inhomogeneous layers of the skin. Indeed, the true transmis sion spectrum of tissues of most animals is inadequately known.…”

Section: Resultsmentioning

confidence: 99%

Photodegradation of Serum Bilirubin in the Gunn Rat

Hewitt¹,

Klein²,

Lucey³

1972

Neonatology

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“…OCA2 type II, unlike type I, retains tyrosinase activity and therefore OCA2 albinos do synthesize pheomelanin (see figure 1) and have a variable capacity to develop pigmented patches or ephelides on exposed skin which may, as in normal white skin, provide some protection from UV damage and cancer [106,107]. Early studies showed that isolated skin of an albino was similar to that of white Europeans in UVB transmission capacity but very different from that of African black skin [108].…”

Section: Skin Cancer In Albinosmentioning

confidence: 99%

Was skin cancer a selective force for black pigmentation in early hominin evolution?

Greaves

2014

Proc. R. Soc. B.

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Melanin provides a crucial filter for solar UV radiation and its genetically determined variation influences both skin pigmentation and risk of cancer. Genetic evidence suggests that the acquisition of a highly stable melanocortin 1 receptor allele promoting black pigmentation arose around the time of savannah colonization by hominins at some 1-2 Ma. The adaptive significance of dark skin is generally believed to be protection from UV damage but the pathologies that might have had a deleterious impact on survival and/or reproductive fitness, though much debated, are uncertain. Here, I suggest that data on age-associated cancer incidence and lethality in albinos living at low latitudes in both Africa and Central America support the contention that skin cancer could have provided a potent selective force for the emergence of black skin in early hominins.

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Relative efficiency of pigment and horny layer thickness in protecting the skin of Europeans and Africans against solar ultraviolet radiation*

Cited by 136 publications

References 10 publications

Ethnic Variation in Vellus Hair Follicle Size and Distribution

Ethnic Variation in Vellus Hair Follicle Size and Distribution

Photodegradation of Serum Bilirubin in the Gunn Rat

Was skin cancer a selective force for black pigmentation in early hominin evolution?

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