A photostable long-wave UVA filter used in Europe and Asia as an alternative to avobenzone. Not approved in the US; a phthalate impurity in some batches is now capped in the EU.
DHHB absorbs UVA1 (peak around 354 nm), the same band as avobenzone, but it stays stable in sunlight. It is common in European and Asian sunscreens and is permitted in the EU up to 10%; it is not an approved sunscreen active in the US.
In 2024 German biomonitoring found a banned reproductive-toxic phthalate (di-n-hexyl phthalate, DnHexP) turning up in people's urine, traced in part to contaminated DHHB. In 2025 the EU's safety committee confirmed DHHB is safe up to 10% provided the impurity stays below 260 ppm, with under 1 ppm as the target.
UVA1 absorption and photostability are well established, and toxicology reviews find low absorption (around 0.15%), no genotoxicity and a large margin of safety at 10%. The phthalate issue is a manufacturing impurity, not a property of DHHB itself, and is now limited in the EU.
Available data show low acute toxicity, no genotoxicity and minimal irritation or sensitisation. With 0.15% dermal absorption and daily sunscreen use at 10%, the margin of safety was about 4,700, well above the usual threshold of 100.
In 250 archived German urine samples, DHHB metabolites first appeared in 2012; intake was far below the no-effect level. Separately, oral-dosing data showed that a phthalate impurity (DnHexP, a reproductive toxicant) in some DHHB batches reaches users, which the authors say warrants reassessment.