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Description of key information

Key value for chemical safety assessment

Bioaccumulation potential:
no bioaccumulation potential

Additional information

Studies have been conducted on the absorption, distribution, metabolism and excretion of radiolabelled sodium cyanurate (equivalent to 77.5% CYA) after single i.v. and repeated oral administration. No metabolism or accumulation was demonstrated in either of the two animal studies in dogs and rats with 100% of the radioactive label recovered in urine and faeces. Over 98% of the cyanuric acid was absorbed from the GI tract. The findings of the animal studies are upheld in a pilot study in humans ingesting swimming pool water where > 98% of a measured dose of CYA was recovered in urine within 24 hours of dosing (Dufour et al (2006). In oral ingestion studies in 2 volunteers, total recovery of cyanuric acid was 21 and 21.2 mg and interpolated 90% excretion was at 3.1 or 3.5 h (t1/2~ 1 h). The volunteers ingested 100 ml of water containing 214 ppm cyanurate (or 21.4 mg cyanurate) thus essentially 100% was recovered in the urine. 

In dermal absorption studies where human skin was tested with a pool concentration of unlabelled cyanuric acid and chlorine, only 0.06 μg/cm2total cumulative absorption was detected over the 24 h exposure period (Moody 1993). Employing a value of 1.83 m2for the total body surface area of a 70 kg human, would imply an exposure of 1.1 mg for a 24 h exposure period. Assuming a worse case maximum exposure time of 5 h daily the data suggests that 0.2 mg/day would be absorbed through a swimmers skin. For a standard water cyanuric acid concentration of 55 ppm, 0.2 g of cyanuric acid would be contained in 3.6 mL pool water. Therefore exposure by the oral route could easily supersede that of dermal.