The Interplay Between Chemical Sunscreens and Diabetes Progression: A Call for Safer Alternatives

Introduction

The prevalence of diabetes continues to be a significant global health challenge, with increasing attention paid to various environmental and lifestyle factors that may contribute to its development and progression. A plausible observation has emerged regarding a potential relationship between the increased use of certain chemical sunscreens and the rising incidence or progression of diabetes. This report aims to explore the scientific basis for this concern, focusing on the role of specific chemical UV filters as endocrine-disrupting chemicals (EDCs), and to advocate for safer, more sustainable sun protection alternatives.

Understanding Endocrine Disruption and its Relevance to Diabetes

The human endocrine system is a complex network of glands and hormones that regulate nearly every physiological process, including metabolism, growth, development, reproduction, and mood. Crucially, it plays a central role in maintaining glucose homeostasis through hormones like insulin and glucagon.

Endocrine-disrupting chemicals (EDCs) are exogenous substances or mixtures that alter the function(s) of the endocrine system and consequently cause adverse health effects in an intact organism, its progeny, or subpopulations (WHO/UNEP, 2012). EDCs can exert their effects through various mechanisms, including mimicking natural hormones, blocking hormone receptors, altering hormone synthesis or transport, or modifying hormone metabolism (Gore et al., 2015). When the endocrine system is disrupted, the delicate balance required for proper metabolic function can be compromised, potentially leading to insulin resistance, impaired glucose tolerance, and an increased risk of type 2 diabetes.

Chemical UV Filters as Potential Endocrine Disruptors

Many chemical UV filters commonly used in sunscreens are known or suspected EDCs due to their molecular structures allowing them to interact with hormone receptors. These chemicals are readily absorbed through the skin, entering the bloodstream and becoming detectable in various bodily fluids (Mancuso et al., 2021; Matta et al., 2020). The systemic absorption of these compounds raises significant concerns about their potential long-term health effects, particularly on metabolic health.

The following chemical UV filters ( which are widely available in Australian Sunscreens) have been identified as having the most substantial links to endocrine disruption and, consequently, plausible connections to diabetes progression:

• Oxybenzone (Benzophenone-3): Oxybenzone is among the most well-studied chemical UV filters for its endocrine-disrupting properties. Research has consistently demonstrated its ability to exhibit estrogenic, anti-androgenic, and anti-thyroid activity in both in vitro and in vivo studies (Krause et al., 2012; Wang et al., 2016). Its systemic absorption means it can interfere with critical hormonal pathways that regulate insulin sensitivity and glucose metabolism, thereby plausibly contributing to metabolic dysfunction and increasing the risk of type 2 diabetes. Furthermore, studies have linked maternal oxybenzone exposure to changes in sex hormone levels and lower birth weight in offspring, a known risk factor for later-life metabolic disorders (Philippat et al., 2014; Zhang et al., 2021).

• Homosalate: Homosalate is another frequently used UV filter classified as a suspected endocrine disruptor. Studies indicate its ability to interact with estrogen receptors and potentially interfere with thyroid hormone function (Klimova et al., 2021; Schlumpf et al., 2004). Its systemic absorption raises concerns about its ability to influence metabolic regulation and its potential to contribute to insulin resistance or impaired glucose tolerance.

• Octinoxate (Octyl Methoxycinnamate / OMC): This common UVB absorber has also been identified as an EDC, with research suggesting it can affect estrogen and thyroid hormone systems (Krause et al., 2012; Maipas et al., 2021). While human data might be less extensive than for oxybenzone, its demonstrated hormonal activity in animal models and known systemic absorption underscore its potential relevance to metabolic health.

• 4-Methylbenzylidene Camphor (4-MBC): 4-MBC has shown clear evidence of estrogenic and thyroid-disrupting effects in scientific studies (Maipas et al., 2021; Schrader & Steinhauer, 2005). Concerns regarding its endocrine-disrupting potential have led to restrictions or bans in various regions globally. Its documented impact on hormonal balance, and some animal studies indicating effects on fat and lipid homeostasis, suggest a plausible link to metabolic health dysregulation.

The biological plausibility for these chemicals to influence diabetes progression stems from their ability to:

• Interfere with Hormone Receptors: Mimicking or blocking the actions of natural hormones (e.g., estrogen, androgens, thyroid hormones) that are vital for regulating insulin signaling, glucose uptake, and energy expenditure.

• Disrupt Metabolic Pathways: Potentially affecting the function of key organs involved in glucose regulation, such as the pancreas (insulin production) and liver (glucose metabolism), or adipose tissue (fat storage and hormone production).

• Cause Systemic Exposure: Their documented absorption into the bloodstream means they can reach and impact various tissues and organs throughout the body, exerting their endocrine-disrupting effects.

The Australian Context: High Exposure and Cumulative Risk

The potential for endocrine disruption from chemical sunscreens is particularly pertinent in Australia due to the nation's high UV index and prevalent sun protection messaging. Australia has one of the highest rates of skin cancer in the world, leading to widespread and frequent sunscreen use as a critical public health measure (Cancer Council Australia, n.d.-a).

Chemical UV filters, including those listed above such as homosalate, octinoxate, octocrylene, oxybenzone, and avobenzone, are widely present in sunscreens sold across Australia and are approved by the Therapeutic Goods Administration (TGA, 2025). The Cancer Council Australia recommends applying sunscreen liberally – approximately 35 mL (seven teaspoons) for a full adult body application – and reapplying at least every two hours, or more frequently after swimming, sweating, or towel drying (Cancer Council Australia, n.d.-b). This guidance, while essential for preventing skin cancer, also translates to a high cumulative daily and long-term exposure to these chemical UV filters for many Australians. This consistent and significant dermal exposure increases the potential for systemic absorption of EDCs, thereby elevating the potential for their endocrine-disrupting effects and plausible links to conditions like diabetes.

Safer Alternatives: The Benefits of Mineral Sunscreens

Given the accumulating evidence linking certain chemical UV filters to endocrine disruption and their plausible association with diabetes progression, it is imperative to consider and promote safer sun protection alternatives. Mineral-based sunscreens, specifically those formulated with non-nano Zinc Oxide (ZnO), offer a superior and more environmentally conscious option.

Unlike chemical sunscreens, which work by absorbing UV radiation and triggering a chemical reaction within the skin, mineral sunscreens create a physical barrier on the skin's surface. Non-nano mineral particles are larger than 100 nanometers, ensuring they remain on the skin's surface and are not absorbed into the bloodstream (Lademann et al., 2009; Newman et al., 2009). This fundamental difference eliminates the concerns related to systemic absorption and potential endocrine disruption associated with chemical filters.

The advantages of non-nano Zinc Oxide-based sunscreens include:

• Exceptional Human Safety Profile:

  • Minimal Systemic Absorption: Due to their non-nano particle size, these sunscreens are not absorbed into the body, mitigating concerns about internal hormonal interference (TGA, 2018).

  • Broad-Spectrum Protection: Zinc oxide provides excellent broad-spectrum protection against both UVA and UVB rays, crucial for comprehensive skin health and preventing skin cancer.

  • Gentle and Hypoallergenic: They are generally well-tolerated by sensitive skin, making them suitable for a wide range of users, including children and individuals with dermatological conditions (SCCS, 2014).

  • Non-Comedogenic: Non-nano zinc oxide is non-comedogenic, reducing the risk of pore clogging and breakouts.

• Environmental Responsibility:

  • Reef-Safe: Crucially, non-nano zinc oxide and titanium dioxide are considered "reef-safe," meaning they do not contribute to coral bleaching or harm delicate marine ecosystems, unlike chemical UV filters such as oxybenzone and octinoxate (Downs et al., 2016). This aligns with a broader commitment to environmental stewardship and sustainability.

Conclusion

While the critical role of sunscreen in preventing skin cancer remains undisputed, the choice of sunscreen formulation warrants careful consideration in light of emerging scientific evidence. The plausible observations linking the increased use of certain chemical sunscreens to diabetes progression are supported by a growing body of research on endocrine disruption. For Australians, the high rates of skin cancer necessitate frequent and liberal sunscreen application, amplifying potential exposure to these EDCs.

By advocating for and promoting the use of non-nano Zinc Oxide-based sunscreens, we can provide a superior solution that not only offers effective sun protection but also safeguards human health from potential endocrine-disrupting effects and contributes to environmental preservation. This proactive approach supports overall well-being and aligns with efforts to mitigate factors contributing to the rising global burden of diabetes.

References

Cancer Council Australia. (n.d.-a). Are chemical sunscreens safe to use? Retrieved June 11, 2025, from https://www.cancer.org.au/iheard/are-chemical-sunscreens-safe-to-use

Cancer Council Australia. (n.d.-b). Sunscreen FAQs. Retrieved June 11, 2025, from https://www.cancer.org.au/cancer-information/causes-and-prevention/sun-safety/about-sunscreen/sunscreen-faqs

Downs, C. A., et al. (2016). Toxicopathological effects of the sunscreen UV filter, oxybenzone (benzophenone-3), on coral planulae and cultures and its environmental contamination in Hawai‘i. Archives of Environmental Contamination and Toxicology, 70(2), 265–288.

Gore, A. C., et al. (2015). EDC-2: The Endocrine Society's Second Scientific Statement on Endocrine-Disrupting Chemicals. Endocrine Reviews, 36(6), E1–E150.

Klimova, A., et al. (2021). The impact of ultraviolet filters on human reproductive health: A critical review. Environmental International, 157, 106821.

Krause, M., et al. (2012). Sunscreens: Are they safe? Experimental Dermatology, 21(9), 652–659.

Lademann, J., et al. (2009). The penetration of titanium dioxide nanoparticles in sunscreen formulations into the outer stratum corneum and the appendages. Skin Pharmacology and Physiology, 22(4), 184–192.

Maipas, S., et al. (2021). Human exposure to sunscreens: A review of environmental and health concerns. Science of The Total Environment, 766, 144358.

Mancuso, J. M., et al. (2021). Systemic Absorption of Sunscreen Ingredients: A Review of Human Clinical Trials. Journal of Investigative Dermatology, 141(8), 1838–1844.

Matta, M. K., et al. (2020). Effect of Sunscreen Application Under Maximal Use Conditions on Plasma Concentration of Sunscreen Active Ingredients: A Randomized Clinical Trial. JAMA, 323(3), 256–267.

Newman, M. D., et al. (2009). The safety of nanosized particles in titanium dioxide- and zinc oxide-containing sunscreens. Journal of the American Academy of Dermatology, 61(4), 685–692.

Philippat, C., et al. (2014). Prenatal exposure to phthalates and phenols and pubertal development in boys. Environmental Health Perspectives, 122(1), 54–60.

Schlumpf, M., et al. (2004). Endocrine activity of UV filters. Toxicology, 205(1-2), 113–121.

Schrader, G., & Steinhauer, R. (2005). Evaluation of the endocrine modulating activity of 4-methylbenzylidene camphor (4-MBC) in the immature female rat. Toxicology Letters, 159(3), 241–248.

Scientific Committee on Consumer Safety (SCCS). (2014). SCCS opinion on Zinc Oxide (nano form). European Commission.

Therapeutic Goods Administration (TGA). (2018). Nanoparticles in sunscreens: Review of the scientific literature. Australian Government Department of Health. https://www.tga.gov.au/resources/publication/nanoparticles-sunscreens-review-scientific-literature

Therapeutic Goods Administration (TGA). (2025). Literature search and summaries of seven sunscreen active ingredients. Australian Government Department of Health and Aged Care. https://www.tga.gov.au/sites/default/files/2025-02/literature-search-summaries-seven-sunscreen-active-ingredients-20250204.pdf

Wang, L., et al. (2016). In vitro and in vivo estrogenic activities of the UV filter benzophenone-3. Environmental Pollution, 212, 569–576.

World Health Organization/United Nations Environment Programme (WHO/UNEP). (2012). State of the Science of Endocrine Disrupting Chemicals – 2012. WHO Press.

Zhang, T., et al. (2021). Urinary concentrations of parabens and benzophenones and birth outcomes among singleton births in a prospective cohort study. Environmental Health, 20(1), 108.