Optical Brighteners
Fluorescent whitening agents, OBAs, FWAs
What is it?
Optical brighteners are synthetic chemicals added to laundry detergents, paper, some cosmetics and certain fabrics to absorb ultraviolet light and re-emit it as visible blue-white light, creating the illusion of a brighter, whiter appearance. They are not rinsed out: they remain deposited on fabric and skin. Because they are UV-reactive, they are active whenever clothing is exposed to sunlight. They are poorly biodegradable, accumulating in aquatic ecosystems, and studies have shown they can penetrate skin and cause sensitisation reactions.
What it does to your body
Skin sensitisation
Classified as a moderate skin sensitiser; linked to contact dermatitis particularly in people with eczema or sensitive skin who use conventional laundry products.
Endocrine disruption potential
Some optical brightening agents show oestrogenic activity in cell-based studies at higher concentrations, though human evidence is limited.
Environmental accumulation
Resistant to biodegradation, OBAs accumulate in fish tissue and aquatic sediment downstream of populated areas, affecting aquatic ecosystems.
Mutagenicity concerns
Certain stilbene-type optical brighteners show mutagenic activity in the Ames test, a standard assay for genotoxic potential.
Neonatal concern
Continuous skin contact from nappies and baby clothing laundered with optical brighteners raises particular concern for infant skin permeability and absorption.
How widespread is the problem?
Optical brighteners are found in the majority of mainstream laundry detergents globally. Because they are not rinsed out, virtually anyone using mainstream detergents carries them on their skin daily. They are routinely detected in river water and aquatic organisms downstream of populated areas.
Where it hides in your home
Key research
Gloxhuber et al. OBA Safety Review
Regulatory Toxicology and Pharmacology review examining the safety data for optical brightening agents, noting skin sensitisation potential and environmental persistence.
Riva et al. Environmental Persistence of OBAs
Study demonstrating the environmental persistence of stilbene-type optical brighteners in aquatic environments and their accumulation in fish tissue.
EWG Optical Brightener Ingredient Review
EWG database entry and review of optical brightening agent safety data, flagging concerns for skin sensitisation and environmental impact.
Unlike most chemicals that you ingest or inhale, optical brighteners are deposited directly onto fabric against your skin with every wash. As long as you continue using detergents containing them, exposure is continuous. Switching to optical-brightener-free detergents is the complete solution.