D-gluconic acid, compound with N,N''-bis(4-chlorophenyl)-3,12-diimino-2,4,11,13-tetraazatetradecanediamidine (2:1)

Endpoint summary

Additional information

The toxicity of Chlorhexidine digluconate to aquatic organisms was tested in several studies covering different trophic levels.

In a study on the acute toxicity of Chlorhexidine digluconate towards fish (OECD 203) the LC50 was determined to be 2.08 mg a.i. CHDG/L, employing the zebrafish (Brachydanio rerio) as the test organism. Acute toxicity towards invertebrates (OECD 202) was tested with the water flea Daphnia magna, and the EC50 was established at 0.087 mg a.i. CHDG/L. Algal toxicity (OECD 201) was found to be higher with EC50values of 0.0101 mg a.i. CHDG/L and 0.0187 mg a.i. CHDG/L for biomass production and growth rate, respectively. The EC10 for growth rate was determined to be 0.0135 mg a.i. CHDG/L. All tests were performed according to the OECD Guidelines.

The substance concentration in the medium during the fish test was not measured during the study. However, results from the daphnia test reveal that the test substance concentration was stable over the test period of 48 hours. Therefore, it can be assumed that also during the fish test the test substance concentration was stable under the semistatic conditions with daily renewal of the medium. Measurements during the algae test revealed stability of the test item over 72 hours.

Although no substance specific analytical measurement was performed in the OECD202 study, the effect value retrieved based on nominal concentrations is plausible and acceptable. This is supported by the OECD211 study which contains substance specific analytical monitoring.

The OECD 211 study was performed as a semi-static test design with 3 times per week test medium renewal. Adult mortality occurred only in the highest test concentration (0.3 mg test item/l corresponding to 61.8 µg a.i. CHDG/l) and started after 5 days of incubation (10% mortality). Analytical monitoring indicated that the substance concentration was sufficiently maintained.

Based on the analytical results and adult mortality results from the OECD 211 study it can be concluded for an OECD 202 study that the substance concentration should be maintained within a period of 48h and a 48h EC50 acute toxicity value should clearly be >61.8 µg a.i. CHDG/l. This indicate that the available OECD 202 study is reliable and the available nominal effect value of 87 µg a.i. CHDG/l is plausible and acceptable as an acute effect value.

A test on reproduction of Daphnia magna was performed according to the OECD Guideline 211. A steep dose-response relationship was found. While at 0.02 mg a.i. CHDG/L no significant effectswere observed,all parent animals died at 0.06 mg a.i. CHDG/L. The NOEC was found to be 0.02 mg a.i. CHDG/L for all examined endpoints.

The toxicity of Chlorhexidine gluconate 20 % Solution was evaluated in a 28 day juvenile fish growth test (Oncorhynchus mykiss) according to OECD TG 215 under semi-static test conditions. The test item Chlorhexidine gluconate 20 % Solution caused significant reductions on weight gain of 20.5, 24.7 and 27.4% at test concentrations of 0.36, 1.02 and 2.86 mg test item/L nominal (equivalent to 0.11, 0.20, 1.02 mg test item/L mean measured) considering 28 days after exposure start. The corresponding NOEC was 0.13 mg test item/L nominal (0.065 mg test item/L mean measured).

The acute toxicity of Chlorhexidine digluconate towards bacteria was tested according to the OECD Guideline 209, by determining the inhibition of respiration of activated sludge. The EC50 was established to be 25 mg a.i. CHDG/L.

In a laboratory activated sludge processing facility, a clear correlation between Chlorhexidine digluconate concentrations and the treatment efficiency was found. At 0.5 mg/L no effects on TOD and TOC elimination as well as on nitrification were observed.