Following a request from the European Commission, the EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS) provides a scientific opinion regarding the safety of the use of gaseous chlorine dioxide (ClO2) as preservative that is slowly released in cold food storage areas.
The chlorine dioxide gas is generated in situ from tubes that contain two reactants, which upon activation slowly release gaseous ClO2. The tubes are to be used in cold storage rooms or in refrigerators for domestic use. The Panel noted that the mode of generation of ClO2 proposed by the applicant is different from the ones already used and accepted so far.
The Panel is aware that the use of the material proposed by the applicant may lead to inhalation of ClO2, but the possible risk resulting from exposure of the consumer by inhalation was not assessed because this is outside the remit of the Panel.
The evaluation of the preservative effect of gaseous ClO2 is outside the remit of the Panel.
The applicant has submitted a dossier in support of its application for the authorisation of gaseous ClO2 for use as a preservative in cold food storage areas. In consideration of the well-known reactive nature of gaseous ClO2, the Panel agreed to assess, as a first step, to what extent chlorinated species are generated by the interaction of gaseous ClO2, under the proposed conditions of use, with some model food matrices.
To this end, and upon request from the Panel, the applicant generated additional data showing that, under the measured in-use conditions in a refrigerator, only a small amount of the total releasable ClO2 from the tube was detected. The maximum detected concentration of ClO2 was 0.043 ppm, which corresponds to 15 μg/120 L. The mean concentration was 0.029 ppm, which corresponds to 10.2 μg/120 L. The applicant also provided experimental data showing that the release of one of the two reactants during use was very low. The data covering a period of 28 days showed that only < 0.005% of the total amount of the gaseous reactant will be released during the intended application duration.
From the data provided by the applicant, under domestic refrigerator-like experimental conditions, the treatment of model food matrices with gaseous ClO2 led to low amounts of by-products, did not produce chlorinated organic by-products, and chlorate was not detected in the model food matrices. The Panel considered that the data indicated the absence of formation of potentially adverse chlorinated compounds in the model food matrices used by the applicant. However, the Panel noted the limitations of the model food matrices; in addition owing to the type of cold area used (a domestic refrigerator) in which a small size tube was used to generate the gaseous chlorine ClO2, the consideration of absence of formation of potentially adverse compounds is restricted to these conditions and do not apply to larger areas where bigger tubes can be used.
According to the applicant, the only by-products resulting from the proposed use of gaseous ClO2 are chlorite and chlorate; therefore, the safety of these by-products has been assessed. The toxicity database for chlorite and chlorate is limited, but did not indicate concern about a genotoxic or carcinogenic potential.
The ANS Panel did not perform an estimate of exposure, because no potentially adverse substances were identified in the initial step of the assessment.
The Panel concluded that, under the conditions of use proposed by the applicant, the consumption of foods treated with use of gaseous ClO2 under the proposed domestic refrigerator-like conditions of use would not be of safety concern.
A new assessment would be warranted in case of any change in the conditions of use.
The Panel recommended that the risk of inhalation of gaseous chlorine should be considered, particularly in the case of large cold storage areas. In this respect, the Panel draws attention to the risk of misuse e.g. large tubes for the production of ClO2 being used in domestic refrigerators.