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Key value for chemical safety assessment

Effects on fertility

Effect on fertility: via oral route
Endpoint conclusion:
adverse effect observed
Effect on fertility: via inhalation route
Endpoint conclusion:
no study available
Effect on fertility: via dermal route
Endpoint conclusion:
no study available
Additional information

There is a 2 -gen reproductive study of MCA available in rats as part of a study investigating reproduction toxicity of DPB (disinfection by-products). Itv was concluded that MCA did not induce effects on reproduction at the levels tested. Moreover, in the 90 -day studies in mice and rats no effects on the reproductive organs were observed.

The growth of mouse antral follicles and the concentration of estradiol in the medium by incubation with 0.25 to 1 mM MCA decreased, which was interpreted as toxicity to the ovaries of mice (Jeong et al. 2016). These concentrations also showed cytotoxicity in the in vitro genotoxicity studies.

Effects on developmental toxicity

Effect on developmental toxicity: via oral route
Endpoint conclusion:
adverse effect observed
Effect on developmental toxicity: via inhalation route
Endpoint conclusion:
no study available
Effect on developmental toxicity: via dermal route
Endpoint conclusion:
no study available
Additional information

An aqueous monochloroacetic acid solution was used in Long Evans rats from 6-15th day of pregnancy in doses of 0, 17, 35, 70 or 140 mg/kg bw and administered daily by bolus dosing (oral gavage). In the high dose group mothers, there was a reduction in body weight gain; the organ weights were not changed compared to the controls. Only in the fetuses of this dose group malformations of the cardiovascular system, especially the left ventricle, were statistically significantly increased. There were no skeletal malformations (Smith et al. 1990).

Ten Sprague-Dawley rats were given drinking water with 1570 mg/L neutralized MCA throughout their pregnancy, which corresponded to 193 mg/kg bw/day. Neither maternal toxicity nor developmental toxicity, and in particular, no significantly increased incidence of malformations of the heart was detected. The incidence of heart malformations in the control group was 2.15% and 4.55% in the MCA group (Johnson et al., 1998ab). The findings in the study by Smith et al. (1990) could not be reproduced. These may be due to the high bolus peak concentration.

Justification for classification or non-classification

According to MAK (2019): In a study of prenatal toxicity in rats, there was an increased incidence of malformations of the cardiovascular system at the highest gavage dose of 140 mg/kg bw/day MCA (Smith et al. 1990). The NOAEL was 70 mg/kg bw/day. These results could not be reproduced when neutralized MCA was administered with the drinking water at a dose of 193 mg/kg bw. The different toxicokinetics in the two types of application may contribute to the different NOAELs. For the toxicokinetic transfer of the NOAEL of 70 mg/kg bw to a concentration in workplace air, the following are taken into account: the species-specific correction value (1:4) corresponding to the toxicokinetic difference between rat and humans, the experimentally determined almost complete absorption (98.5%), the body weight (70 kg) and the respiratory volume (10 m3) of humans as well as the assumed 100% inhalation absorption. This results in a corresponding concentration for the workplace of 121 mg/m3, which is approximately 60 times higher than the MAK value of 2 mg/m3 (0.5 ml/m3). As such MCA and its sodium salt are assigned to pregnancy group C. [Group C: There is no reason to fear damage to the embryo or foetus when MAK and BAT values are observed.]

Based on the available 2 -gen study and absence of effects on the reproductive organs in the 90 -day studies in mice and rats no classification is needed for reproductive toxicity.

Based on the absence of effects in the drinking water study using neutralized MCA at a high dose of 193 mg/kg bw throughout pregnancy no classification for developmental toxicity is needed. The cardiovascular effects seen at 140 mg/kg bw using oral gavage may be due to bolus application; the next lower level of 70 mg/kg bw was a NOAEL.