Working under the sun could be a major cause of skin cancer worldwide, according to new data from the World Health Organization and the International Labour Organization.
The two United Nations agencies jointly announced new estimates Wednesday that link working outdoors in the sunlight to non-melanoma skin cancer. Their report, published in the research journal Environment International, says that nearly 1 in 3 deaths from non-melanoma skin cancer is caused by ultraviolet radiation from outdoor work.
The new data would rank occupational ultraviolet radiation exposure – performing work duties outdoors, in the sun – as the third largest occupational carcinogen, behind only asbestos and silica dust.
“It’s actually a really big deal, because it’s the first estimates of work-related skin cancer that we have globally,” said Frank Pega, an epidemiologist at WHO and the study’s lead author. “[Solar radiation] is a well-known occupational carcinogen.”
“Non-melanoma skin cancer” refers to a group of cancers that develop in the upper layers of the skin, beyond the melanocyte cells that produce skin pigment. It includes cancers like basal cell carcinoma and squamous cell carcinoma.
Ultraviolet radiation from sunlight is a known risk factor for skin cancers: According to the US Centers for Disease Control and Prevention, solar radiation can damage skin cells and, over time, cause skin cancer.
As a result, WHO’s International Agency for Research on Cancer recognizes solar radiation as a Group 1 carcinogen, something that is known to cause cancer in humans.
According to Pega, it’s taken seven years to put together enough comprehensive data to issue the new estimates.
The researchers examined cases of workplace exposure to solar radiation and instances of non-melanoma skin cancer across nearly 200 countries. The report pooled 763 labor force surveys to parse 166 million observations in 2000, 2010 and 2019, making this one of the largest studies of sunlight and cancer in the workplace, Pega said.
“To produce these estimates, the bar is very high for the evidence,” he added. “The evidence needs to be very strong for us to consider proceeding.”
The report found that, in 2019, 1.6 billion workers were occupationally exposed to ultraviolet radiation: nearly 30% of all working-age people, often in industries like agriculture, construction and fishing. Males and young adults were most exposed, but the overall number of people exposed to ultraviolet radiation at work dropped 32% from 2000 to 2019.
Despite that decline, the number of skin cancer deaths linked to occupational UV radiation climbed about 90% over the same period, the researchers found. Workplace UV radiation exposure caused 18,960 deaths from non-melanoma skin cancer in 2019, the majority of whom were men.
“Occupational exposure to [UV radiation] is common and causes substantial, inequitable and growing attributable burden of [non-melanoma skin cancer],” the study says.
Many of the workers exposed to solar radiation, Pega added, also work in the informal economy, without an employer, earning income from collecting recycling materials or working in outdoor markets. People who work around reflective surfaces, like fishers surrounded by water, are also at an increased risk of skin cancer because they experience more intense radiation.
Previous WHO estimates have found that occupational exposure to UV radiation increases the odds of developing non-melanoma skin cancer by 60%. According to Pega, though, the research team didn’t have enough high-quality data to make similar determinations about melanomas.
Globally, Pega said, skin cancer is typically concentrated in areas like Europe, North America and Australia. But in the new data, occupational skin cancer was more likely than he expected to be found in low- and middle income countries, particularly in parts of Africa.
“Skin cancer is normally concentrated in high-income countries in the global north,” he explained. “It’s surprising, because we would have never been able to expect this.”
The workplace hazards of sun exposure, however, are not unavoidable, Pega said. Employers and policymakers can take steps to reduce workers’ risk of getting exposed to UV radiation. For example, employers might shift hours for outdoor workers away from peak sunlight around noon.
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Employers could also take steps to provide shade to outdoor workers, and labor laws could include requirements for protective clothing like broad-brimmed hats and long-sleeve shirts. Sunscreen doesn’t hurt either, Pega said.
At a medical level, Pega urged improved access to early screening for skin cancer, so the disease can be detected and treated quickly. Medical interventions are particularly important for workers in informal economies, he said, since informal outdoor workers often operate without an employer and outside the reach of labor laws.
And as a last step, countries could begin including skin cancer from occupational sunlight exposure to national lists of workplace diseases, which could open the door for affected employees to receive workers’ compensation, Pega added.
“It’s a real shift in thinking,” he said. “Occupational health systems will really have to adapt.”