Cutaneous Manifestations of Climate Change

Extreme-Heat-Sun
Climate change can drive bacterial and fungal infection, seborrheic, contact and AD, psoriasis, melanoma, acne, skin cancer, alopecia areata, HS. Credit: Getty Images
To learn more about the potential dermatologic effects of climate change and needed actions from clinicians, we interview expert Eva R. Parker, MD, FAAD.

With an increasing occurrence of extreme weather events associated with climate change, researchers anticipate negative effects on many facets of health. Several recently published papers described the wide-ranging skin manifestations that may result from these disasters, with some study authors issuing a call to action for dermatologists to help reduce the expected consequences.1-5

A review published in October 2022 in the Journal of Climate Change and Health detailed the array of cutaneous diseases that may occur due to exposure to floods, wildfires, and extreme heat, as highlighted below.1

Floods. Research has shown that traumatic wounds such as lacerations and punctures comprised nearly one-third of dermatologic manifestations associated with flooding. These injuries can result from “contact with submerged debris, clinging to trees and vegetation, and climbing structures to escape floodwaters,” as stated in the review.1 In addition, many patients with traumatic wounds experience secondary bacterial and fungal infections.

Skin and soft tissue infections due to exposure to typical pathogens such as Staphylococcus aureus, Streptococcus pyogenes, and Pseudomonas aeruginosa, as well as atypical mycobacteria and fungi including dermatophytosis, chromoblastomycosis, and mucormycosis have been reported after flooding events.

Prolonged contact with contaminated floodwater can also lead to noninfectious dermatoses such as irritant contact dermatitis, immersion foot syndrome, and pernio. 

Wildfires. Air pollutants released during wildfires have been found to exacerbate atopic dermatitis (AD), and exposure to these compounds has been linked to increases in clinic visits and hospitalizations for AD in pediatric and adult populations. Wildfire-related pollutants may also possibly cause or exacerbate other inflammatory disorders including acne and psoriasis. Some findings suggest that the carcinogenic compounds may increase the risk of melanoma and nonmelanoma skin cancers in exposed individuals.

Extreme heat. Extreme heat events linked to global warming may trigger or aggravate skin conditions such as miliaria – with Staphylococcus superinfection in some cases – as well as Grover’s disease, folliculitis, intertrigo, and seborrheic dermatitis. In addition, extreme heat is likely to influence the frequency and severity of acne and AD flares.

High temperatures may also increase the risk of S. aureus infections, viral infections including hand, foot, and mouth disease, and superficial fungal infections such as tinea pedis and tinea versicolor.

The review authors note that the negative health manifestations associated with extreme weather events will continue to have a disproportionate impact on individuals from marginalized and vulnerable groups, adding further to the burden of existing health disparities affecting these populations.

To learn more about the potential dermatologic effects of climate change and needed actions from clinicians, we interviewed lead author Eva R. Parker, MD, FAAD, assistant professor of dermatology at Vanderbilt University Medical Center in Nashville, Tennessee; co-chair of the American Academy of Dermatology’s Expert Resource Group for Climate Change and Environmental Issues; and associate editor of the Journal of Climate Change and Health.

What does the available evidence suggest about the current and potential impact of climate change on dermatologic disorders?

Dr Parker: Because skin is a very large and complex organ and represents our body’s primary interface with our environment, many cutaneous diseases are climate sensitive. These include autoinflammatory diseases, in particular atopic dermatitis, psoriasis, pemphigus, and lupus; cutaneous malignancies; acne and folliculitis; thermoregulatory capacity, heat-exacerbated dermatoses including transient acantholytic dermatosis and miliaria; nutritional diseases; psychodermatoses; vector-borne diseases; and flood-associated skin infections. Because climate impacts vary by region, the diseases dermatologists may observe will differ based on geography.

Importantly, the impacts of climate change disproportionately affect Blacks, Indigenous Peoples, people of color, those of lower socioeconomic status, and other marginalized communities as well as vulnerable populations including women, children, and people with disabilities.

What are some of the proposed mechanisms underlying these effects?

Dr Parker: Broadly speaking, climate change includes a wide range of direct and indirect environmental impacts including extreme heat, severe storms and flooding, drought, wildfires, air pollution, increased UV from stratospheric ozone depletion, microplastic pollution, deforestation, and ecosystem destruction. All of these have direct and indirect impacts on health, but the specific mechanisms vary depending upon the climate variable and the disease.

A growing body of evidence has emerged supporting that exposure to air pollution increases both the incidence and severity of atopic dermatitis. For example, maternal exposure to traffic-related air pollution is associated with epigenetic modification in utero that favors a Th2 phenotype, increasing the risk of atopic dermatitis in infants.6

Wildfire smoke is also linked with increases in pruritus and outpatient visits for atopic dermatitis in both children and adults, and a greater need for systemic medications in adults.

We also know that UV and air pollution have a synergistic effect on photoaging and cutaneous carcinogenesis. A key player in the pathogenesis of many of these processes is the aryl hydrocarbon receptor, a ligand-activated transcription factor whose activation by components of air pollution triggers a molecular cascade that results in activation of matrix metalloproteinases causing collagen degradation, inflammatory cytokine production, down-regulation of filaggrin with associated skin barrier defects, increased transepidermal water loss, and alteration of the skin’s microbiome.

With respect to heat, we know that the skin plays a key role in thermoregulation by dissipating heat through vasodilation and the evaporation of sweat. However, during episodes of extreme heat, these protective cooling mechanisms may be overwhelmed, increasing the risk of deadly heat stroke. We should all be aware that age, numerous medications, and comorbidities such as cardiovascular disease and obesity can alter thermoregulatory capacity, increasing the risk of acute heat-related illnesses. Chronically, heat is known to trigger or exacerbate many skin diseases such as intertrigo.

The impact of stress on skin disease is often underrecognized. The devastating effects of extreme weather events such as hurricanes and wildfires often trigger numerous acute and chronic mental health illnesses in victims, leading to exacerbation of underlying cutaneous diseases such as acne, psoriasis, eczema, and alopecia areata. Attempts to cope with this stress may lead to the induction of delusions of parasitosis, neurotic excoriations, or trichotillomania.

Additionally, during extreme weather events, patients’ medications may be lost or destroyed and access to care is often disrupted. 

What are recommendations for clinicians regarding managing these risks as well as advocating for measures to reduce the impact of climate change?

Dr Parker: Dermatologists can adopt 3 approaches to reduce climate impacts: patient education, decarbonization, and advocacy. Consider how climate change may impact your patients individually and teach patients about their particular vulnerabilities. Advise patients to check indices for heat, air quality, and UV – numerous apps and websites exist for this. Incorporate heat counseling into your sun protection advice, and if extreme weather is imminent, make sure your patients have a plan and an emergency kit that contains their medications.

We must acknowledge that the US health care sector is a large producer of greenhouse gases and air pollution, thus minimizing the negative environmental consequences of our care delivery is critical. For a tangible action, sign up for My Green Doctor, a practice management tool for greening medical offices that is a free membership benefit from the American Academy of Dermatology (AAD).

Other meaningful steps include reducing travel by relying more on virtual platforms to learn, deliver care, and conduct residency interviews. When you do have to travel to meetings, consider purchasing carbon offsets to minimize the impacts of that travel.

If you are interested in learning more or getting involved in advocacy efforts, please join the AAD’s Expert Resource Group on Climate Change and Environmental Affairs. Consider inviting a climate expert to give a lecture to your department or state medical society, and when voting in both political and medical society elections, consider candidates who support climate action. Additionally, join a local climate advocacy group to help advocate for health and resiliency in your community.

What broader measures and additional studies are needed in this area?

Dr Parker: Large knowledge gaps remain in how climate change impacts many skin diseases, and funding opportunities are now beginning to emerge for climate-related research. One that comes to mind is hidradenitis suppurativa – while it is likely very susceptible, we know very little about how climate change impacts this disease.

We must also train the next generation of physicians to be climate-literate, yet many medical schools and residency programs lack formal climate-health curricula. Lastly, dermatology societies, hospital systems, and academic centers must commit to rapid decarbonization over the next decade and prioritize climate-health research and education.

References:

  1. Parker ER, Mo J, Goodman RS. The dermatological manifestations of extreme weather events: a comprehensive review of skin disease and vulnerability. J Climate Change Health. 2022;8:10062. doi:10.1016/j.joclim.2022.100162
  2. Silva GS, Rosenbach M. Climate change and dermatology: an introduction to a special topic, for this special issue. Int J Womens Dermatol. 2021;7(1):3-7. doi:10.1016/j.ijwd.2020.08.002
  3. Fathy R, Rosenbach M. Climate change and inpatient dermatology. Curr Dermatol Rep. 2020;9(4):201-209. doi:10.1007/s13671-020-00310-5
  4. Williams ML. Global warming, heat-related illnesses, and the dermatologist. Int J Womens Dermatol. 2020;7(1):70-84. doi:10.1016/j.ijwd.2020.08.007
  5. Parker ER, Boos MD. Dermatology’s call to emergency action on climate change. Published online September 8, 2022. Int J Dermatol. doi:10.1111/ijd.16301
  6. Stefanovic N, Flohr C, Irvine AD. The exposome in atopic dermatitis. Allergy. 2020;75(1):63-74. doi:10.1111/all.13946
  7. The Nature Conservancy. Carbon offsets, illustrated. Accessed online October 11, 2022.