Sensitivity of embryonic Chinese rare minnow (Gobiocypris rarus) to fragrance ingredients: A comparison to its juveniles and embryonic zebrafish (Danio rerio)

Rapid expansion of chemical markets globally has shown the need to identify hazardous characteristics of commercial chemicals to protect public health and the environment, and the need for chemicals registrations. In China, a major hub for chemical production in Asia, fish toxicity data using a native species, the Chinese rare minnow ( Gobiocypris rarus ), are required for chemical registration, potentially leading to redundant testing and increased animal use. In this context, we examined the toxicity of 26 fragrance ingredients with diverse physicochemical properties on G. rarus embryos using a newly developed method. The median lethal concentration values of these fragrances spanned two orders of magnitude and exhibited a positive correlation with water solubility. Chemical toxicity distribution and chemical ratio distribution models were constructed to compare the sensitivity across the developmental stages (juvenile vs. embryo) of G. rarus and across species ( G. rarus vs. Danio rerio ). Using apical endpoints that indicate lethality showed a sensitivity ranking for the 26 compounds as D. rerio embryos > G. rarus juveniles > G. rarus embryos. Alternatively, when median malformation-based effect concentration values G. rarus in embryos were applied in the modeling, D. rerio embryos remained the most sensitive, while G. rarus embryos and juveniles showed comparable sensitivity. The present study provided valuable data on rare minnow FET and promote the adoption of alternative toxicity testing methods in Chinese regulatory frameworks. It also highlights the need to acquire more toxicity data for various compounds using G. rarus embryos and expand the applicability domain of the FET with G. rarus embryos.