DDT, Atopic Dermatitis, and the Consequences of Overreaction

After the disastrous effect of disease on soldiers and civilians during World War I, the world was afraid and hypersensitive to disease and the bugs that carry disease.^[1] By 1939, Paul Muller, a Swiss chemist, discovered that dichloro-diphenyl-trichloroethane was an effective chemical that killed insects on contact.^[1] As World War II ramped up, use of this chemical was widespread, especially in the tropical South Pacific, where American military planners feared malaria and typhus and went so far as to spray the chemical indiscriminately over entire islands.^[2] After the war, use expanded worldwide, even though suspicions of ecological problems were raised as early as the mid-1940s.^[2] Dichloro-diphenyl-trichloroethane, now commonly called DDT, didn’t just kill insects, but also accumulated in the fats of animals that eat insects.^[2] This accumulation of DDT became more concentrated in animals higher up the food chain, causing problems.^[2] The most notable problems were in birds, where DDT caused the thinning of eggshells, dramatically increasing death rates of birds like pelicans and the bald eagle.^[3] Additionally, DDT accumulates in humans and may be linked to an increased danger of pancreatic cancer, mental issues, and birth problems.^[4] The most concerning feature of DDT is its persistence in the body. Although it was banned in the United States in 1972 measurable levels of DDT and its byproducts are still detectable in the bodies of nearly all people.^[2] This is a classic case where a focused response may have some benefit, but the excessive reaction to danger causes bigger problems. It’s like an allergy; it’s like atopic dermatitis.

The word atopic is derived from the Greek word for “out of place” and refers to the inheritance patterns of allergic conditions. Dermatitis is from the Greek word derma- meaning “skin” and the ending -itis, referring to inflammation. Atopic dermatitis is a heritable, inflammatory skin condition also referred to as eczema.^[5] It is one of the most common skin conditions worldwide and affects around seven percent of American adults.^[6] Most people with atopic dermatitis have symptoms during childhood, with around ½ of cases diagnosed before age one.^[6,7] Women are more likely than men to have atopic dermatitis.^[6]

Those with atopic dermatitis may consider it a real pest. Symptoms include:^[7]

• Itching, also called pruritus
• Dry skin
• Inflammation
• Rash
• Damaged skin, including bumps, crusting, thickening, and cracking

For many people, atopic dermatitis is either chronic (long-lasting) or chronically relapsing, with periods of flare-up and remission that can last years at a time.^[5] This long-lasting element can accumulate, like DDT, and create long-term issues with mental health, including low self-esteem, low mood, low confidence, and damage to relationships.^[7] Atopic dermatitis can also concentrate into other problems in a process called the “atopic march,” where the allergic reaction of atopic dermatitis can lead to allergic asthma and nasal inflammation.^[5,8,9]

Inside the body, atopic dermatitis is actually less like DDT and more like our overuse of DDT to blanket huge swaths of the planet in bug poison. Skin has an extremely tough job: to keep out dangerous substances, let safe substances through, and sense the environment - all at the same time. With atopic dermatitis, the skin barrier is disrupted, and it can’t perform its job properly.^[8] Genetic differences in barrier proteins can cause the skin to misidentify harmless things in the environment as dangerous.^[8] These proteins then trigger an inflammatory cascade where signal molecules such as thymic stromal lymphopoietin (TSLP) and various interleukins saturate the skin and recruit immune cells.^[8] This can combine with other genetic biases towards certain immune cells (such as T helper cells, eosinophils, and neutrophils) and changes in the skin microbiome, making this condition chronic and persistent into adulthood for many people.^[8,9]

So what can be done? For most people, atopic dermatitis clears up during childhood - it’s like the 1972 DDT ban. For others, the process crawls on, and lifestyle or medical solutions must be found. Lifestyle changes can help reduce interaction with skin allergens and lower the burden of atopic dermatitis. Skin creams and topical anti-inflammatory medications like corticosteroids and calcineurin inhibitors can help people reach tolerable levels during a flare-up, though corticosteroids may not be suitable for long-term use.^[7] People with severe atopic dermatitis may need to step on the gas for more serious solutions. These solutions include phototherapy, the use of UV light on the skin, and systemic therapies taken orally or injected. Systemic therapies include short-term use of corticosteroids, antimetabolites, janus kinase (JAK) inhibitors, and biologics that target specific interleukins. Unfortunately, even with all of these options, only around half or fewer people with atopic dermatitis successfully control the disease.^[7] There is a need for additional medications with lower side effect profiles and easier treatment regimens.^[7] With the help of clinical trials, we may be able to solve atopic dermatitis without ruffling too many feathers.

Creative Director Benton Lowey-Ball, MWC, BS, BFA

References:

[1] Fisher G. Presentation speech by professor G. Fischer, member of the staff of professors of the Royal Caroline Institute. Nobel Lectures, Physiology or Medicine 1942-1962. Amsterdam: Elsevier Publishing Company; 1964. Available at https://www.nobelprize.org/prizes/medicine/1948/ceremony-speech/

[2] Jarman WM, Ballschmiter K. From coal to DDT: the history of the development of the pesticide DDT from synthetic dyes till Silent Spring. Endeavour. 2012 Dec 1;36(4):131-42. https://doi.org/10.1016/j.endeavour.2012.10.003

[3] Harada T, Takeda M, Kojima S, Tomiyama N. Toxicity and carcinogenicity of dichlorodiphenyltrichloroethane (DDT). Toxicological research. 2016 Jan;32(1):21-33. https://doi.org/10.5487/TR.2016.32.1.021

[4] Beard J, Australian Rural Health Research Collaboration. DDT and human health. Science of the total environment. 2006 Feb 15;355(1-3):78-89. https://doi.org/10.1016/j.scitotenv.2005.02.022

[5] Wollenberg A, Barbarot S, Bieber T, Christen‐Zaech S, Deleuran M, Fink‐Wagner A, Gieler U, Girolomoni G, Lau S, Muraro A, Czarnecka‐Operacz M. Consensus‐based European guidelines for treatment of atopic eczema (atopic dermatitis) in adults and children: part I. Journal of the European Academy of Dermatology and Venereology. 2018 May;32(5):657-82. https://doi.org/10.1111/jdv.14891

[6] Fuxench ZC, Block JK, Boguniewicz M, Boyle J, Fonacier L, Gelfand JM, Grayson MH, Margolis DJ, Mitchell L, Silverberg JI, Schwartz L. Atopic dermatitis in America study: a cross-sectional study examining the prevalence and disease burden of atopic dermatitis in the US adult population. Journal of Investigative Dermatology. 2019 Mar 1;139(3):583-90. https://doi.org/10.1016/j.jid.2018.08.028

[7] Zuberbier T, Orlow SJ, Paller AS, Taïeb A, Allen R, Hernanz-Hermosa JM, Ocampo-Candiani J, Cox M, Langeraar J, Simon JC. Patient perspectives on the management of atopic dermatitis. Journal of Allergy and Clinical Immunology. 2006 Jul 1;118(1):226-32. https://www.sciencedirect.com/science/article/abs/pii/S0091674906004507

[8] Yang L, Fu J, Zhou Y. Research progress in atopic march. Frontiers in immunology. 2020 Aug 27;11:1907. https://doi.org/10.3389/fimmu.2020.01907

[9] Locksley RM. Asthma and allergic inflammation. Cell. 2010 Mar 19;140(6):777-83. https://www.cell.com/cell/fulltext/S0092-8674(10)00240-0

Reference Style changed from APA to AMA January, 2026