Photoprotection messages and ‘SunSmart’ programmes exist mainly to prevent skin cancers and, more recently, to encourage adequate personal sun exposure to
elicit a vitamin D response for healthy bone and immune systems. Several developed countries maintain intensive research networks and monitor solar UV radiation to support
awareness campaigns and intervention development. The situation is different in sub-Saharan Africa. Adequate empirical evidence of the impact of solar UV radiation on
human health, even for melanomas and cataracts, is lacking, and is overshadowed by other factors such as communicable diseases, especially HIV, AIDS and tuberculosis. In
addition, the established photoprotection messages used in developed countries have been adopted and implemented in a limited number of sub-Saharan countries but with
minimal understanding of local conditions and behaviours. In this review, we consider the current evidence for sun-related effects on human health in sub-Saharan Africa,
summarise published research and identify key issues. Data on the prevalence of human diseases affected by solar UV radiation in all subpopulations are not generally
available, financial support is insufficient and the infrastructure to address these and other related topics is inadequate. Despite these limitations, considerable progress
may be made regarding the management of solar UV radiation related health outcomes in sub-Saharan Africa, provided researchers collaborate and resources are allocated
Sub-Saharan Africa consists of 43 countries south of the Sahara (Figure 1). This area spans latitudes 13°N to 33°S with an average annual daytime temperature of
21 °C. The UV Index is often higher than 10 (extreme) and rarely drops below 7, except at high altitudes and towards the tip of South Africa in the winter months
(June, July and August). The land varies from equatorial rainforest to dry woodland, savannah, grassland and mountain grassland.
The major beneficial outcome of solar ultraviolet radiation (UVR) exposure on human health lies in the endogenous production of vitamin D, while adverse outcomes of excess
exposure include skin cancers and eye diseases.1 Extensive research and public health interventions relating to the consequences of solar UVR on human health
have been carried out in many developed countries; however, the same is not true for sub-Saharan Africa. Limited information suggests health and exposure risks do exist in
this area of the world, although accessing published and verified data is a challenge, because most sub-Saharan countries do not have operational health information systems
or ground-based networks to monitor solar UVR. The aim of this review is to broaden the understanding of the effects of solar UVR on human health in sub-Saharan Africa by
considering an update of relevant health outcomes and by documenting public perceptions and interventions.
The countries of sub-Saharan Africa.
A systematic approach was used to identify key published resources of substance and appropriate scientific merit. Databases searched were African Journals Online, SABINET,
Academic Search Premier, Pubmed, SciELO, Medline, JSTOR, Web of Science and Scopus. Keywords entered were “solar UV radiation” AND health AND [country];
“sun exposure” AND health AND [country]; sunburn AND [country]; “skin cancer” AND [country]; albinism AND “sun exposure” AND [country];
[range of sun-related eye diseases] AND “sun exposure” AND [country]; “sun protection” AND [country]; “sun behaviour” AND [country]; and
“sunsmart awareness programme” AND [country]. Reference lists of collected articles including reports of the World Health Organization (WHO) were examined. Using
the same keywords, Google was searched for grey literature, a particularly important source in the African context. The websites of national departments of health and cancer
associations were investigated for information on ‘SunSmart’ programmes and sun-related health statistics.
Sun exposure is the major environmental risk factor for melanoma and for the non-melanoma skin cancers (NMSCs), basal cell carcinoma (BCC) and squamous cell carcinoma (SCC).
The lifetime risk of these tumours is low in those with black skin and highest in those with fair skin, estimated at a difference of up to 60-fold. There are other major
differences depending on skin colour.2 While BCCs represent about 80% of cutaneous tumours in fair-skinned people, they are the least
common of the skin tumours
in deeply pigmented people, in whom SCCs are the most frequent. In dark-skinned individuals, SCCs occur most often on the lower limbs (developing from antecedent lesions
such as ulcerations, burns and scars), followed by the head and neck. In fair-skinned people, SCCs are found almost entirely on the most sun-exposed areas of the body, such
as the face and ears. Unlike the situation in individuals with fair skin, the majority of melanomas in black skin occur on a lower extremity, particularly on the sole of the
foot, a body site with little pigmentation.
The occurrence of NMSCs in sub-Saharan Africa is rarely monitored. However, the UVR-attributable disease burden caused by SCCs and BCCs for some of the countries in this
region was calculated for the year 2000 using three levels of skin pigmentation, models for global assessment and country-specific population-weighted average daily
ambient UVR.3,4 Using actual results, the annual incidence of SCC in Black individuals was estimated as 1
in 100 000 in a township near Soweto,
Johannesburg in 1966–1975,5 whereas the age-standardised annual incidence of BCC in the Netherlands is currently more than 140 in
100 000. A study
in Kano, Nigeria revealed that 6.3% of all cancers in female individuals and 9.9% in male individuals were NMSCs in
1995–2004.6 One recent report based
on rural hospitals in Kenya found that 44% of all cutaneous malignancies were SCCs and 7% were BCCs.7
For melanoma, which accounts for more than 80% of skin cancer deaths, there are also few figures available regarding incidence and prevalence for sub-Saharan Africa,
although, as for the NMSCs, the UV-attributable disease burden from this tumour was calculated as approximately 5100 deaths for the year 2000 in this area of the
world.4 For South Africa, in 2001 – one of the last years for which statistics are currently available – the National
recorded an age-standardised incidence rate per 100 000 for melanoma of 1.1 for Black males, 1.5 for Black females, 22.5 for White males and 17.4 for White
females.8 The incidence has risen since then and the South African Cape region was estimated in 2009 to have the highest incidence
of melanoma in the world
at 69 new cases per 100 000 White individuals9 (Australia has 65 per 100 000).
Accurate figures on the prevalence of skin cancers in all subpopulations in sub-Saharan Africa are required, especially to record any changes in incidence. Such data
are needed to inform the public regarding photoprotection and to improve clinical awareness.
Melasma is an uneven hyperpigmentation which appears as dark, macular, pigmented patches on the face.10 The cause of melasma is
complex – genetic, hormonal,
therapy and lifestyle-related contributions are implicated, as is sun exposure. For example, 51% of patients reported sun exposure as a triggering factor and 84% reported sun
exposure as an aggravating factor in a study based in Tunisia, with a high lifetime sun exposure increasing the risk of severe melasma
represents a significant problem in sub-Saharan Africa, primarily because of its impact on quality of life. It is suggested to have a significant psycho-emotional effect on
women.12 While different scales, including the Melasma Quality of Life scale, have been devised, these have not been tailored effectively
for the cultural needs
of multi-ethnic subpopulations.
Few statistics are available for sub-Saharan Africa regarding the prevalence of other skin disorders induced by either acute sun exposure, such as sunburn, or by chronic sun
exposure, such as photoageing and actinic keratoses, the latter recognised as premalignant lesions.
Oculocutaneous albinism (OCA) is a genetically inherited, autosomal recessive condition characterised by hypopigmentation of the skin, hair and eyes as a result of a
lack of, or reduced, melanin. There are many people living with OCA in sub-Saharan Africa; estimates indicate a prevalence of 1 in 4728 in Zimbabwe, 1 in 3900 in South
Africa and as high as 1 in 1000 in the Tonga tribe in Zimbabwe.13,14 Individuals with OCA are at increased risk
from the adverse effects of sun exposure, such
as extreme sun sensitivity and photophobia. SCCs of the neck and head are the most common cutaneous tumours seen in African patients
with OCA,15 with melanomas
There is a range of eye diseases associated with sunlight exposure – ophthalmohelioses. These diseases include photoconjunctivitis, photokeratitis and activation
of ocular herpes simplex virus following acute exposure to solar UVR, and NMSCs of the lid and conjunctiva, ocular melanoma, pinguecula (local degeneration of conjunctiva),
pterygium (inflammation, proliferation and invasive growth on conjunctiva and cornea), climatic droplet keratopathy (epithelial degeneration), age-related cataracts and
possibly age-related macular degeneration following chronic exposure to solar UVR.
Few data are available for sub-Saharan Africa that estimate the scale of health problems caused by these ophthalmohelioses, although it is recognised that this area has
the highest regional burden of blindness at 20% of the world’s blindness and only 11% of the world’s population.16 Indeed,
1% of Africans are
blind.17 Cataracts account for approximately 50% of the cases of blindness worldwide. The evidence to link cataract development with sun
exposure is strongest
for cortical cataracts, the form found in about 33% of subjects with cataracts in one survey based in rural Tanzania.18 In the
first population-based study in
an African setting (Nigeria), it was reported that there were 5000 per million population with functional low vision
and 340 per million blind.19 One-quarter
of the functional low vision cases were as a result of corneal opacity and about 3% were as a result of pterygium. The prevalence of functional low vision was highest
in the northern part of Nigeria, which is drier and sunnier than the south. Earlier studies in South Africa showed an annual incidence of cataract blindness of 0.14% with
a prevalence of 0.6% in a rural population in KwaZulu-Natal,20 and a prevalence of 0.3% in rural northern
Figures for the incidence and prevalence of corneal and other external eye diseases in sub-Saharan Africa are not generally available for recent years, although such
disorders are recognised to be very common. For example, corneal diseases, the majority being pterygium and climatic droplet keratopathy, were found in more than 20%
of a mixed race community in the north-western Cape (South Africa),22 and pterygium represented 9% of all new cases at an eye clinic in
(Nigeria)23 and 8% of ocular problems in adults aged 18–49 in rural Nigeria, most of which occurred in outdoor
Concern has been expressed recently that sub-Saharan Africa is not on track to achieve the main goal of ‘VISION 2020: The Right to Sight’ – to eliminate
avoidable blindness by 2020.25 This imminent failure has been attributed to the lack of eye care teams, staff development,
infrastructure and community
programmes.25 In this context, it is disappointing to note that the national target for cataract surgery in South Africa was downgraded
in 2010 from 2000 to
1500 per million population, when at least 2000 per million per year is required to eliminate cataract blindness.26 Guidance for the
general public about
protecting the eye by wearing hats with wide brims or sunglasses that meet an appropriate standard for solar UVR protection would be very helpful in reducing the risk of
UV-induced downregulation of immunity to a variety of antigens has been demonstrated in humans. The pathways involved are complex,27 and
may involve vitamin D
which has many immunoregulatory properties.28 The majority of vitamin D in most people is produced as a result of sun exposure. The
vitamin D status of almost
all populations in sub-Saharan Africa is unknown but, from the incomplete data available, is lower in South Africa compared with the tropical
However, even near the equator, there can be a high rate of vitamin D deficiency, as demonstrated in adults in Ethiopia
(10°N)30 and Guinea-Bissau
(12°N).31 Nutritional rickets remains prevalent in some tropical countries despite good sunshine exposure, although this may be as a
result of a low calcium
intake rather than a deficiency in vitamin D.32
From many studies covering a variety of approaches, it can be concluded that UVR and/or vitamin D have the potential to protect against some inflammatory diseases and
autoimmune diseases, such as multiple sclerosis, while decreasing the immune surveillance against skin tumours and infectious diseases. Each of these categories is
discussed briefly below.
In the context of diseases in sub-Saharan Africa, the light-sensitive dermatoses (e.g. polymorphic light eruption where there is a lack of immunosuppression following sun
exposure with development of an allergic response) do not constitute a major health problem as they are much less common in people with pigmented skin and occur rarely in
regions near the equator.33 Similarly, multiple sclerosis is uncommon in the indigenous Black, Coloured or Indian people of Africa.
In southern Africa, there is a
relatively high prevalence of multiple sclerosis in White migrants from Europe with a lower prevalence in White African-born people, possibly as a result of the protective
effect of early exposure to high levels of solar UVR.34
UVR not only causes mutations but also downregulates immunity, an effect which is recognised to be critical in the development of skin tumours. For the same dose of UVR,
fair-skinned people exhibit more DNA damage,35 a higher production of immune mediators and a higher degree of
immunosuppression36 than those with
darker skins. This difference is likely to contribute to the increased susceptibility of individuals with fair skin to develop skin cancers compared with individuals with
more pigmented skin.
It is unclear whether UV-induced immunosuppression can affect the course of human infectious diseases, apart from triggering the reactivation from latency of herpes
simplex virus. Some human infections exhibit a strong seasonal incidence. For example, influenza is highly seasonal in southern Africa with the peak incidence occurring in
the drier cooler winter months: the seasonality becomes less pronounced with closeness to the equator.37 This pattern is also seen
in other parts of the world,
and has been attributed to lower vitamin D levels (and thus less effective innate immunity) in the winter compared with the summer in countries outside the tropics.
Tuberculosis presents a major public health issue in sub-Saharan Africa with Nigeria having the fourth largest tuberculosis burden in the world and South Africa the fifth
largest. Many of the new cases of tuberculosis are co-infections with HIV; currently sub-Saharan Africa accounts for 79% of the worldwide HIV–tuberculosis burden.
From a survey of studies conducted in 11 countries or regions around the world (including South Africa), a seasonal pattern of tuberculosis is indicated with a peak in
the spring and summer months.38 This pattern has been explained by low vitamin D levels in the winter leading to less effective
control of microbial growth.
Hypovitaminosis D is highly prevalent in tuberculosis patients and is associated with an increased risk of disease progression, although it is not known if the low level
is a symptom or is causal.31 Recent research has considered whether vitamin D prevents reactivation of tuberculosis.39 With
regard to HIV, while
some observations support a role for UVR in altering the interaction of the virus with the host, clinical and epidemiological reports have not demonstrated that exposure
to sunlight changes the course of the disease.40 Many HIV-infected people are vitamin D deficient but the impact of this deficiency on
disease progression is
unknown and should be investigated.
Vaccination represents a major public health strategy in sub-Saharan Africa in attempts to control common infections, particularly in childhood. The potential of UVR to
decrease the efficacy of vaccination by downregulating immunity has not been rigorously assessed for human vaccines although there are reports indicating that a less
effective immune response is induced if the vaccine is administered in the summer compared with the winter, and in tropical compared with
Perhaps of most relevance in the context of sub-Saharan Africa is finding that the protection against tuberculosis following vaccination correlates positively with distance
from the equator.42 More severe UV-induced immunosuppression nearer to the equator as a result of the higher sun intensity could account
for this result.
Sun-related exposure, protection, perceptions and awareness
The people of sub-Saharan Africa are genetically diverse: migrants from other countries have settled here since the Greeks, Romans and Arabs 3000 years ago, Europeans since
the 1600s and Asians since the 1800s. If this heterogeneity is added to the range of environments and social conditions in sub-Saharan Africa, it can be anticipated that
solar UVR will not have straightforward health outcomes. In addition, the only country to possess solar UV monitoring instruments in this region is South Africa, where a
four-station network has been in operation since the early 1990s. The network aims to provide measured data to the media daily to inform the public regarding times of
intense solar irradiation.
Personal sun exposure studies in sub-Saharan Africa are non-existent, inaccessible or sparsely documented. One of the few studies, based in Durban (South Africa),
emphasised the risk of sunburn and NMSC for children and outdoor workers.43 Schoolchildren in this city experienced a mean total
daily solar exposure of
two Standard Erythemal Doses, with boys experiencing greater sun exposure than girls and outdoor physical activity being the most important determinant of sun exposure.
Knowledge about sun protection is not widespread in sub-Saharan Africa. Sunscreen use and environmental awareness were investigated in White Cape Town beachgoers; the
results showed that only 50% wore sunscreen,although 90% of respondents cited skin cancer as a potential adverse effect of excess sun exposure and a few
acknowledged other health effects.44 A survey of students attending four large tertiary institutions in South Africa showed that 82.3% knew
sunlight may have harmful ocular effects, but only a quarter reported that they often wore sunglasses outdoors and 38.5% recognised that not all spectacles and contact
lenses were protective.45
Sun protection is of special importance for individuals with OCA to prevent skin damage and thus lessen the risk of skin cancer. Most OCA cases present late in the tumour
process and patients do not complete treatment because of a lack of funds or for cultural reasons. Education regarding protective clothing, sunscreens, indoor occupations
and early treatment of skin lesions would be beneficial. An investigation in Tanzania of albinos’ understanding of skin cancer risk and attitudes toward sun protection
showed that 78% of respondents believed skin cancer was preventable, 63% knew that skin cancer was related to the sun and 77% thought sunscreens afforded sun
protection.46 Reasons for not wearing a hat included fashion, culture and heat. Hat-wearing among children with OCA and visual
impairment in northern South
Africa was high (although the brim width was not always sufficient) and one-third used sunscreens.1
Few sub-Saharan countries have active, sun-related awareness and disease prevention campaigns although some work has been carried out to improve primary health care for
the management of cataracts and skin cancer. The non-governmental African Organisation for Research and Training in Cancer promotes cancer control and palliative care, and
several sub-Saharan countries have cancer societies. The Cancer Association of South Africa is one of the few with a SunSmart programme. As outlined above, there are
currently insufficient data to assess the extent of sun-related health effects and the relevance of any interventions in sub-Saharan Africa.
Several challenges will need to be overcome and opportunities created to improve the understanding of the health impacts of solar UVR and to implement interventions locally
for a sustained improvement in public health. The WHO INTERSUN programme is one possible mechanism. For this programme to be effective in sub-Saharan Africa, fundamental
research is needed on local disease prevalence and incidence, exposure patterns (occupational, early life and recreational) and sun awareness, especially the lack thereof
but also how awareness is affected by cultural beliefs and practices. The capacity to initiate and manage public health information to support such research is required.
For example, a National Cancer Registry has only recently been re-instated in South Africa. There are additional unknowns such as any consequence of climate change in
sub-Saharan Africa. Ground-based monitoring of ambient solar UVR is limited, mainly because of financial and personnel restrictions. Little research has been done on
potential interactions of solar UVR with local diseases, such as HIV, AIDS, malaria and tuberculosis, and with vaccine responses. Research is also needed on personal
solar UVR exposure and sun protection studies on at-risk subpopulations should be conducted. The potential of solar UVR to decrease the efficacy of vaccination by
immunosuppression also merits investigation.
Sun education needs to be tailored for sub-Saharan Africa and its multi-ethnic subpopulations. Sun protection and health intervention programmes targeted at children
with OCA have proved relatively successful48 and similar targeted interventions for groups at particular risk may be an
appropriate way forward. A
multidisciplinary approach for research and intervention programmes is essential, especially given the limited resources, capacity and infrastructure, and the high
burden of communicable diseases in sub-Saharan Africa. Seeking health co-benefits that arise from dovetailing research with society and government priorities could
be the best strategy to manage the health consequences of solar UVR in sub-Saharan Africa.
The preparation of this manuscript was funded, in part, by a CSIR Parliamentary Grant to C.W. and a South African Medical Research Council Career Award to L.D.
We declare that we have no financial or personal relationships which may have inappropriately influenced us in writing this paper.
C.W. was the project leader, conceptualised the article content and compiled the sun protection and albinism sections. M.N. compiled the immune system section, B.S. compiled
the melasma section, L.D. compiled the skin cancer section and M.O.O. compiled the ophthalmohelioses section. C.W., M.N., B.S., L.D. and M.O.O. wrote the manuscript. G.C.
gave input to the challenges and opportunities section.
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