Source: https://reeflabel.com/ingredients/bisdisulizole-disodium/ Chemical (organic) UV filter · Reef research: Limited data # Bisdisulizole Disodium (Neo Heliopan AP) A water-soluble UVA filter used outside the US. Banned in - Palau Also excluded where only mineral sunscreen is allowed - Maui County - Hawaiʻi County Not approved in the US, so US sunscreens do not contain it. ## Where it’s restricted Named in the law or guidance | Location | Status | Since | | --- | --- | --- | | [Palau](https://reeflabel.com/locations/palau/) [law text ↗](https://www.palaugov.pw/wp-content/uploads/2018/10/RPPL-No.-10-30-re.-The-Responsible-Tourism-Education-Act-of-2018.pdf) | In force | January 1, 2020 | ### Also not allowed under mineral-only rules Bisdisulizole Disodium (Neo Heliopan AP) isn’t named in these laws, but they allow only mineral (zinc oxide or titanium dioxide) sunscreens, so a product containing it is excluded anyway. - [Maui County (Maui, Molokaʻi, Lānaʻi)](https://reeflabel.com/locations/maui-county/) (in force since October 1, 2022) - [Hawaiʻi County (Big Island)](https://reeflabel.com/locations/hawaii-county/) (in force since December 1, 2022) ## What the reef research says Bisdisulizole disodium is the same substance as disodium phenyl dibenzimidazole tetrasulfonate (DPDT), a water-soluble sunscreen UV filter. Dalton et al. (2024) studied DPDT on the surface of a human skin mimic and wrote that the high-energy photons released as it relaxes can be detrimental to human health. Leon et al. (2008) proposed an in vitro method for estimating how much DPDT is absorbed through skin. The reef evidence is thin. - [Mitchelmore et al. 2021, Environ Toxicol Chem: critical review of organic UV filter exposure, hazard and risk to corals (Table 1 lists bisdisulizole disodium as disodium phenyl dibenzimidazole tetrasulfonate)](https://pmc.ncbi.nlm.nih.gov/articles/PMC8048829/) - [Dalton J, et al. 2024. Evaluating the Fluorescence Quenching of Troxerutin for Commercial UV Sunscreen Filters. ACS Phys Chem Au 4(6):750-760 (PMID 39634638)](https://pubmed.ncbi.nlm.nih.gov/39634638/) - [Leon Z, et al. 2008. Reversed-phase ion-interaction chromatographic method for in-vitro estimation of the percutaneous absorption of water-soluble UV filters. Anal Bioanal Chem 391(3):859-66 (PMID 18365182)](https://pubmed.ncbi.nlm.nih.gov/18365182/) **Related ingredients:** [Ensulizole](https://reeflabel.com/ingredients/ensulizole/), [Sulisobenzone](https://reeflabel.com/ingredients/sulisobenzone/) Last reviewed October 14, 2026. ### Label names we match - bisdisulizole disodium - disodium phenyl dibenzimidazole tetrasulfonate - neo heliopan ap ### Regulatory status **Wikidata:** [Q4917278](https://www.wikidata.org/wiki/Q4917278) **US FDA:** Not approved in the US. **EU:** Approved, max 10%. **Protects against:** UVA-II.