nano 有点争议，总有人认为不安全，对uva 防护不好，也有可能进入人体影响健康（但这些通常是细胞试验，不是正常人涂抹防晒霜的研究结果）。

下面引用某学术文章：

A key unresolved issue with ZnO-NPs is their local safety, with suggestions that they may penetrate the stratum corneum barrier, gain access to viable epidermis cells, and cause potentially toxic responses (European Commission Scientific Committee on Consumer Safety, 2012, Senjen, 2012, Section, 2017). Toxicity concerns are largely based on cell culture studies showing that ZnO-NPs can induce cytotoxicity, oxidative stress, and DNA and metabolic damage when applied for less than 6 hours to human liver cells (HepG2), epidermal cells (A431), keratinocytes (NCTC2544), and fibroblasts (Akhtar et al., 2012, Alarifi et al., 2014, Kocbek et al., 2010, Sharma et al., 2009). The only study of repeated topical application of 68ZnO-NP sunscreen to human volunteers found 68Zn ions in the blood and urine (Gulson et al., 2010, Gulson et al., 2012), although the penetration of intact ZnO-NPs was not proven.

原文链接：https://www.sciencedirect.com/science/article/pii/S0022202X18326551#:~:text=Toxicity%20concerns%20are%20largely%20based,et%20al.%2C%202009).

上面引用的文章是支持nano的，毕竟细胞研究不等于宏观用于人体皮肤上的表现。这篇文章说找了志愿者涂nano 防晒霜没有发现安全隐患