EFSA publishes practical guide on nano risk assessment
The food safety watchdog yesterday published the guide to cover the use of engineered nanomaterials (ENM) across the whole supply chain - including food contact materials, food additives, enzymes and flavourings, as well as animal feed additives and pesticides.
It sets outs a structural method, factors that should be considered and a chronological framework to best ensure a rigorous risk assessment under most current knowledge.
EFSA highlighted that information on nano materials is incomplete and developing constantly. This means its guidance will need to be revised.
Risk assessment paradigm
The body’s scientific committee declared that using a risk assessment method for ENMs was suitable. This involves hazard identification and characterisation followed by exposure assessment and risk characterisation.
The experts stressed the importance of proper characterisation of ENMs in establishing their identity and physico-chemical forms in foodstuffs during tests. Because these forms can alter under different conditions the nano-characterisation should be determined in five stages: manufactured (pristine) state, as delivered for use in food and packaging, as present in food and packaging, as used in toxicity testing and as present in biological fluids and tissues.
Factors such as chemical composition, physico-chemical properties (size, shape, solubility, surface charge and surface reactivity), interaction with biological tissues and possible exposure levels will be used to determine risk.
These properties allow the ENM to be identified and for an evaluation on whether the guidance from EFSA can be employed to arrive at a risk assessment. They are also likely to influence parameters to assess absorption, distribution, metabolism and excretion (ADME).
Anticipated exposure scenarios from proposed uses need also to be outlined before detailed risk assessment can take place, said EFSA.
Toxicity approaches
The guidance outlines six toxicity methods:
- No additional testing needed if there is convincing evidence that use of the nanomaterial does not in an ENM presence in the foodstuff;
- Employ EFSA non-nanoform guidance if ENM completely changes into a non-nanoform in the food before ingestion;
- Hazard identification and characterisation can be based on available data from non-nanoforms where it is shown that the ENM dissolves/degrade in human intestine without absorption;
- Where non-nanoform data on the same substance is available and where an ENM persists in the gut and food stuff – the report recommends the following test method – “comparing information on ADME, toxicity and genotoxicity of the non-nanoform with ADME , repeated-dose 90-day oral toxicity study and genotoxicity information of the ENM”;
- Where ENM presence persists as above but no nanoform data exists, toxicity tests follow EFSA guidelines for “intended use with the modifications in the present ENM Guidance to take into account the nanoproperties”;
- Appropriate in vitro and in vivo studies should be carried out on the ENM.
But the committee noted: “Some test models and standard testing protocols used for non-nanoform substances may not necessarily be appropriate or optimal for the testing of ENM, and ongoing efforts in the research community are currently addressing these issues.”
Exposure assessment
The exposure assessment must begin with information on the ENM added to – or in contact with – the food. While it is best to determine the amount of the ENM present, the experts said this is not always possible because of uncertainties over the naturally present ENMs in products.
Where such data is incomplete the guidelines said it should be assumed that “all added ENM, is present, ingested and absorbed as the nanoform”.
Current uncertainties
EFSA said there are current “uncertainties” on a whole raft of issues, including identification, characterization and detection of ENMs. The guidelines will therefore need updating “based on experience and acquired knowledge”.
To read the full EFSA guidance click HERE
