EFSA Proposes New Health Guidance Values for Trifluoroacetic Acid

Revised ADI and ARfD Values Reflect New Evidence

At the request of the European Commission, EFSA's Pesticide Peer Review Unit re-evaluated the acceptable daily intake (ADI) and introduced, for the first time, an acute reference dose (ARfD) for TFA. The new values are:

• ADI: 0.03 mg/kg body weight per day
• ARfD: 0.6 mg/kg body weight
  (Both expressed as sodium trifluoroacetate)

These values were derived using a weight-of-evidence (WoE) approach, incorporating 170 studies, including developmental and reproductive toxicity data, biomonitoring, and mechanistic studies. A significant driver for the revised ADI was a reduction in thyroid hormone levels observed in an extended one-generation reproductive toxicity study in rats.

Trifluoroacetic Acid: Widespread Use and Exposure

TFA is a persistent degradation product of various industrial chemicals including refrigerants, fluorinated polymers, and pharmaceuticals. It is also a known metabolite of several PFAS and pesticide active substances, which has raised concern over cumulative and long-term human exposure.

Human biomonitoring studies confirm widespread exposure. One study in adults reported TFA serum concentrations with a 97% detection rate (median: 8.46 ng/mL). Notably, TFA was also detected in umbilical cord serum, providing evidence of foetal exposure during pregnancy.

Mechanistic and Health Risk Insights

EFSA concluded that TFA is not genotoxic, based on a comprehensive battery of in vitro and in silico studies. However, evidence of developmental toxicity in rabbits (including ocular malformations) led to the introduction of the ARfD at 0.6 mg/kg bw.

Although no carcinogenicity studies were available, EFSA applied additional uncertainty factors due to data gaps. These included the absence of a long-term carcinogenicity study and the lack of functional immunotoxicity tests.