Here a big list of studies and articles about the negative health effects of sunscreen:
Note: Includes data table listing sunscreen chemicals and their side effects.
Note: This is an FDA document identifying the only two ingredients used in sunblock lotions, zinc and titanium dioxide, that are known to be safe. Explanations on many other common sunscreen ingredients provided as well.
Conclusion: Study found that pregnant women with higher levels of the widely-used sunscreen chemical oxybenzone in their urine are at a higher risk of giving birth to babies with the often fatal digestive defect Hirschsprung’s disease.
Note: Big, comprehensive article covering all known evidence of endocrine-disrupters in consumer products, including sunscreens, and their effects on human health.
Note: Comprehensive article on the evidence of potential neurotoxic effects of many sunscreen chemicals including impaired cognitive development.
Note: Data on UK melanoma rates doubling and tripling over the last few decades, despite sunscreen use also increasing.
Conclusion: This study evaluated urine samples of 413 men and evaluated for concentrations of 5 different benzophenone-type sunscreen chemicals (remember, this stuff accumulates in your body and makes its way to your urine). The men were also evaluated for semen quality to look for associations between higher sunscreen chemical presence in urine and effects on sperm health. What the study found was that for one sunscreen chemical (2,2′,4,4′-tetrahydroxybenzophenone), guys with higher chemical detections in their urine had lower semen quality, including: lower sperm count, inferior sperm movement, and less developed sperm.
Note: Comprehensive article going over the accumulating evidence of the endocrine-disrupting effects of many sunscreen chemicals.
Note: Comprehensive article going over the accumulating evidence of the endocrine-disrupting, reproductive-impairing, and fetal development effects of many sunscreen chemicals.
Note: Article by a medical doctor on why most common sunscreens aren’t so healthy.
The Relation Between Sunscreen Layer Thickness and Vitamin D Production After Ultraviolet B Exposure: A Randomized Clinical Trial (2012)
Conclusion: 37 light-skinned people applied varying thicknesses of SPF 8 sunscreen to their upper body and were exposed to a standard dose of UVB irradiation four times over a two week period. Vitamin D levels were measured before and after. The study found that those who were applying the thickest application of the sunscreen (which is also the recommended dose) experienced an insignificant increase in their vitamin D levels. Thinner applications of sunscreen resulted in better vitamin D production, with vitamin D levels increasing exponentially for the lowest doses of applied sunscreen.
Sunscreens: are they beneficial for health? An overview of endocrine disrupting properties of UV‐filters (2012)
Note: Comprehensive article going over the accumulating evidence of the endocrine-disrupting effects of many sunscreen chemicals, which have been found in the urine samples of 96% of Americans and in 85% of Swiss breast milk samples.
Urinary Concentrations of Benzophenone-Type UV Filters in U.S. Women and Their Association with Endometriosis (2012)
Conclusion: This study evaluated sunscreen chemical levels in urine samples of 600 U.S. women who had also recently been evaluated for endometriosis. Scientists found that those with the highest urine concentrations of sunscreen chemical 2,4OH-BP had a 65% higher risk for endometriosis compared to women who tested with lower amounts of 2,4OH-BP. This is attributed to the known estrogenic hormonal effects of 2,4OH-BP.
Note: Article by Medical Doctor Joseph Mercola on the dangers of many sunscreen products.
Concentrations of the Sunscreen Agent Benzophenone-3 in Residents of the United States: National Health and Nutrition Examination Survey 2003–2004 (2008)
Conclusion: This study evaluated 2,517 urine samples from the U.S. general population (ages 6 and up) and found the sunscreen chemical benzophenone-3 present in over 96% of urine samples.
In Utero Exposure to Benzophenone-2 Causes Hypospadias Through an Estrogen Receptor Dependent Mechanism (2007)
Conclusion: This study exposed pregnant mice to the sunscreen chemical benzophenone-2 to observe the effects of the exposure on the offspring. Another group of pregnant mice were not exposed to benzophenone-2. 14% of the male offspring from the benzophenone-2 group had the penis birth defect hypospadias, whereas none of the male offspring in the control group had hypospadias.
Conclusion: In vivo experiment on juvenile fish demonstrating estrogenic effects of common sunscreen chemicals.
Interaction of Polycyclic Musks and UV Filters with the Estrogen Receptor (ER), Androgen Receptor (AR), and Progesterone Receptor (PR) in Reporter Gene Bioassays (2005)
Note: This study measured and documented hormone-disrupting effects of 7 different sunscreen chemicals on hormone receptors of cell cultures.
Liquid Chromatographic Assay for Common Sunscreen Agents: Application to In Vivo Assessment of Skin Penetration and Systemic Absorption in Human Volunteers. (2004)
Conclusion: Sunscreen chemicals get absorbed by your body and make their way into your bloodstream. “Results from the preliminary clinical study demonstrate significant penetration of all sunscreen agents into the skin.”
Active Ingredients in Sunscreens Act as Topical Penetration Enhancers for the Herbicide 2,4-Dichlorophenoxyacetic Acid. (2004)
Conclusion: Sunscreen chemicals have been proven with blood tests to be “dermal penetration enhancers,” causing an increased absorption by the body of other harmful chemicals such as herbicides, pesticides, and bug sprays.
Systemic Absorption of the Sunscreens Benzophenone-3, Octyl-Methoxycinnamate, and 3-(4-Methyl-Benzylidene) Camphor After Whole-Body Topical Application and Reproductive Hormone Levels in Humans. (2004)
Conclusion: Urine tests have found that sunscreen chemicals can be absorbed into the body, making their way into your bloodstream.
Effects of Active Sunscreen Ingredient Combinations on the Topical Penetration of the Herbicide 2,4-Dichlorophenoxyacetic Acid (2003)
Conclusion: “A number of commercially available [sunscreen] formulations have been shown to enhance the transdermal penetration of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). Most of the active ingredients used in these compounds can individually act as penetration enhancers.” Sunscreens increase your absorption of other harmful chemicals you’re exposed to, such as bug sprays.
Conclusion: Having sunscreen on you increases absorption of harmful pesticides through your skin.
Conclusion: In vitro study demonstrated that 5 different sunscreen chemicals, including one of the most common – oxybenzone, increase breast cancer cell proliferation due to their estrogenic effects.
Sunscreens, Skin Photobiology, and Skin Cancer: The Need for UVA Protection and Evaluation of Efficacy (2000)
Conclusion: Sunscreens prevent burning to the surface of the skin, but they do not prevent damage to the inner, deeper layers of skin. For this reason, sunscreens might actually be causing more harm by allowing people to spend more time in the sun than they otherwise would which leads them to accumulate more damage to their inner layers of skin over time. Very good article explaining how complicated sunscreens actually are with respect to full-spectrum protection and the long-term consequences of using only partial-spectrum protection products.
Note: Mother Jones article providing an overview of the evidence showing that common sunscreens do not typically provide the amount or type of sun protection we’re told they do, they actually cause more harm in the full analysis, and most of the medical experts urging us to use it are either paid off by the cosmeceutical-industrial-complex somehow or they’re just lazy and repeating talking points they haven’t actually investigated at all.
Chronic Sunscreen Use Decreases the Concentration of 25-Hydroxyvitamin D: A Preliminary Study (1998)
Conclusion: Vitamin D levels were measured in 20 long-term users of PABA-containing sunscreen and compared with the vitamin D levels of 20 age-matched controls who don’t use sunscreen. The average vitamin D level of the sunscreen group was a very poor 16 ng/ml, whereas the control group had a much better (and more than double) level of 36 ng/ml. The sunscreen group also had two cases of severe deficiency, but the control group had no cases of severe deficiency.
The Effect of Regular Sunscreen Use on Vitamin D Levels in an Australian Population. Results of a Randomized Controlled Trial (1995)
Conclusion: 113 people age 40 or older were given either an SPF 17 sunscreen or a placebo cream to use daily during an Australian summer. Vitamin D levels were measured before and after and both groups actually had the same vitamin D level increase. So maybe if you’re using a weaker sunscreen sparingly and still get a lot of time out in intense sunlight, you’re okay.
Note: New York Times article reporting on research findings showing sunscreen does not protect against melanoma skin cancer.
Note: Article arguing that sunscreens may actually increase the risk of melanoma skin cancer by allowing people to spend more time in the sun than they would without sunscreen and actually incurring more photodamage as a result.
Conclusion: Sunscreens reduce vitamin D production.
Note: 1980 British Medical Journal article pointing out that many chemicals found in cosmetic and sunscreen products aren’t healthy.