Citral

Citral (CAS 5392-40-5) is the principal lemon-grass aldehyde, a natural fragrance compound that appears at trace concentrations in many detailing products as an odor-masking agent for petroleum solvents and silicones. The substance is on the 26-allergen list under EU cosmetic regulation (Annex III of Regulation 1223/2009) and is one of the more common fragrance sensitisers in topical chemistry.

The health-relevant flag at consumer concentrations is Skin Sens. 1 (H317) — the allergic-skin-reaction classification. Citral does not produce dermatitis in unsensitised individuals; it produces it in the small fraction of users who have already become sensitised through prior exposure, often via cosmetic or fragrance products rather than detailing chemistry. The mixture-classification threshold under EU CLP is 1.0% for inclusion as a Cat 1 sensitiser in a final product; at fragrance-level concentrations (typically 0.1–0.2%) the supplemental EUH208 statement applies instead of a full H317 hazard call.

Environmentally, citral is readily biodegradable (90% in 28 days per the OECD biodegradability method on its EU Method C.4-D test) and does not bioaccumulate (Log Pow 2.76, well below the 4.5 threshold). At trace fragrance use rates the environmental load is negligible relative to the bulk solvent and carrier components of any product it appears in.