While we encourage scientists to investigate the safety of ingredients used by the general public, we are concerned that Downs et al. in their recent publication reached conclusions that are not evidence based and risk doing more harm than good.(1) Benzophenone is an effective ultraviolet (UV) absorbing agent approved by the European Union (EU) and United States Food and Drug Administration (US FDA) for use in sunscreens.(2,3) The compound is a broad-spectrum UV radiation absorber, absorbing both ultraviolet B (UVB) and ultraviolent A (UVA) radiation.(4) Octocrylene is an organic UV filter also used widely in sunscreens for its broad spectrum UV absorptive properties and as a stabilizer for other UV filters such as benzophenone and avobenzone, protecting them from photodegradation.(5) Human and animal absorption of manmade UV filters is well documented; however, there are little data to support direct toxicity in humans, beyond rare contact and photocontact allergies.(6) One should also caution that absorption does not equate with risk. The authors cite three references to support their claim that “benzophenone is an established carcinogen”. The first, from the IARC monograph on benzophenone, concludes that there are no data available supporting carcinogenicity in humans, but that based on the results of experimental animal studies is “possibly carcinogenic to humans”.(7) The second two studies were conducted on rodents.(8,9) These found sufficient evidence for its carcinogenicity in animals, but this does not equate with carcinogenicity in humans. Experimental animal studies of UV filter-induced disruptions in thyroid and sex hormones have been demonstrated to be reversible, and when extrapolating the results of animal studies, similar dose-dependent endocrinopathies would require 30–250 years of daily use in humans under real world use conditions.(10) In contrast, there is a wealth of robust evidence to link excessive UV exposure to the development of skin cancer and sunscreen use to skin cancer prevention.(11) When discussing absorption of benzophenone through the skin, the authors cite two studies conducted by the FDA.(12,13) While both studies quantify the levels of sunscreen active ingredient absorption, neither make reference to these levels being unsafe. In fact, the accompanying press release actively encourages the public to continue using sunscreen.(14) The FDA threshold for systemic absorption referred to in these papers equates to the concentration considered safe by default. The approximated cancer risk associated with plasma concentrations below this threshold would be less than 1 in 100,000 after a single dose. This is considered low enough that no other safety data are required.(15) The finding of ingredients exceeding this level simply means that the FDA requires more data to be submitted before it can be considered safe under the current proposals. We were also perplexed by the description of the EU and FDA as “reckless” in relation to public health, particularly given the increasing numbers of deaths in the US and Europe from malignant melanoma and other skin cancers in the last 10 years.(11) The authors also imply that dermatologists should not be taken seriously when recommending regular reapplication of sunscreen, despite this being the consensus across all international medical organizations including the World Health Organization (WHO), American Academy of Dermatology (AAD), and Centers for Disease Control and Prevention (CDC). The nature of the language and erroneous conclusions drawn in this paper have caused us concern as physicians. Concerned patients have approached us bringing newspaper cuttings, from articles linked to this publication, warning that the use of old sunscreen may cause cancer. We fear that articles such as this undermine the public’s trust in sunscreen as an essential method to reduce the burden of UV-induced skin cancer and in doing so (by avoiding its use) may in fact increase their risk of cancer. We consider it important that the clear benefits of sunscreen use, along with the global burden of skin cancer, should be considered in any commentary examining potential or theoretical risks of sunscreen ingredients. Sunscreens certainly protect one of the most potent and established human carcinogens of all – ultraviolet radiation. This article references 15 other publications.

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评论商用防晒产品中奥克立林降解导致二苯甲酮随时间累积

虽然我们鼓励科学家调查公众使用的成分的安全性，但我们担心 Downs 等人。(1) 二苯甲酮是一种有效的紫外线 (UV) 吸收剂，已获得欧盟 (EU) 和美国食品和药物管理局 (US FDA) 批准) 用于防晒霜。(2,3) 该化合物是一种广谱紫外线辐射吸收剂，可吸收紫外线 B (UVB) 和紫外线 A (UVA) 辐射。(4) 奥克立林是一种有机紫外线过滤剂，也广泛用于防晒剂因其广谱紫外线吸收特性以及作为其他紫外线过滤剂（如二苯甲酮和阿伏苯宗）的稳定剂，保护它们免受光降解。(5) 人类和动物对人造紫外线过滤器的吸收有充分的记录；然而，除了罕见的接触和光接触过敏之外，几乎没有数据支持对人类的直接毒性。(6) 还应注意吸收并不等同于风险。作者引用了三个参考文献来支持他们的说法，即“二苯甲酮是一种已确定的致癌物”。第一个来自 IARC 关于二苯甲酮的专着，得出的结论是，没有可用的数据支持对人类的致癌性，但根据实验动物研究的结果得出的结论是“可能对人类致癌”。(7) 后两项研究是针对啮齿类动物。(8,9) 这些发现了足够的证据证明其对动物具有致癌性，但这并不等同于对人类的致癌性。紫外线过滤剂引起的甲状腺和性激素干扰的实验动物研究已被证明是可逆的，当推断动物研究的结果时，类似的剂量依赖性内分泌疾病需要在现实世界中每天用于人类 30-250 年(10) 相比之下，有大量强有力的证据表明过度暴露于紫外线与皮肤癌的发展和使用防晒霜与预防皮肤癌有关。(11) 在讨论二苯甲酮通过皮肤的吸收时，作者引用了两个FDA 进行的研究。(12,13)​​ 虽然这两项研究都量化了防晒活性成分的吸收水平，但都没有提到这些水平是不安全的。事实上，随附的新闻稿积极鼓励公众继续使用防晒霜。(14) 这些论文中提到的 FDA 全身吸收阈值相当于默认情况下被认为是安全的浓度。单次给药后，与低于此阈值的血浆浓度相关的近似癌症风险将低于 100,000 分之一。这被认为是足够低的，不需要其他安全数据。(15) 发现超过这个水平的成分仅仅意味着 FDA 需要提交更多的数据才能根据当前的建议被认为是安全的。我们还对欧盟和 FDA 将其描述为在公共卫生方面“鲁莽”的描述感到困惑，特别是考虑到过去 10 年美国和欧洲因恶性黑色素瘤和其他皮肤癌而死亡的人数不断增加。(11) 作者还暗示，在推荐定期重新涂抹防晒霜时，不应认真对待皮肤科医生，尽管这是包括世界卫生组织 (WHO)、美国皮肤病学会 (AAD) 和中心在内的所有国际医学组织的共识疾病控制和预防 (CDC)。这篇论文的语言性质和得出的错误结论引起了我们作为医生的关注。忧心忡忡的患者带着与本出版物相关的文章中的剪报与我们联系，警告说使用旧防晒霜可能会导致癌症。我们担心此类文章会削弱公众对防晒霜作为减少紫外线引起的皮肤癌负担的基本方法的信任，而这样做（通过避免使用）实际上可能会增加他们患癌症的风险。我们认为，在审查防晒成分的潜在或理论风险的任何评论中，都应考虑使用防晒霜的明显好处以及皮肤癌的全球负担，这一点很重要。防晒霜当然可以保护最有效和最确定的人类致癌物之一——紫外线辐射。本文引用了 15 篇其他出版物。