5 Conclusions and future considerations

This report summarises the current state of knowledge on food safety aspects and the status of legislation for seaweed used as foodstuff, with a special focus on Nordic conditions.

Based on the current knowledge, the most critical food hazards relevant for seaweed harvested in the Nordic countries are iodine, cadmium, and inorganic arsenic.

Iodine is an essential micronutrient, but both insufficient and excessive intake may pose health problems. Some seaweed products contain very high levels of iodine, so iodine is classified as a hazard in this context.

Other important food hazards to be considered, are lead and mercury, Bacillus spp in heat treated products, kainic acid in dulse, and allergens.

Available data and studies on microbiological hazards in seaweed are limited. Harvesting in clean water and general good hygienic practice is important, as in all food production, and the general hygiene legislation must be followed.

The levels of heavy metals and iodine vary greatly between and within species, and can be affected by age, growing conditions, and processing methods. The data presented on iodine, cadmium, inorganic arsenic, lead, and mercury in seaweed from Denmark, the Faroe Islands, Iceland, Norway, and Sweden, confirm these variations, both between and within species. The differences between the species seem to be quite similar.

For both food business operators and public agencies, it is important to differentiate between seaweed species, since the levels of contaminants can vary substantially from one species to another. Although the amount of data in this report is limited, it can be used as an indication as to which species are most challenging in terms of heavy metals and iodine in Nordic seaweed production.

The Nordic data shows that the brown algae generally have the highest levels of iodine, with the species sugar kelp, winged kelp, oarweed and tangle containing the highest levels. Species of red and green algae are considerably lower in iodine than the brown algae, except for the red algae wrack siphon weed. Oarweed can have exceptionally high levels of inorganic arsenic, whereas cadmium levels are highest in several brown and red algae.

Processing methods may alter the content of hazards; in particular, the iodine content can be reduced. However, some products may still contain excessively high levels of iodine after processing. Since a high intake of iodine may cause health concerns, consumers should be appropriately informed about the possible risk of such products, to enable them to make an informed choice. Dietary advice and labelling are possible tools to be used for this information.

Other hazards should also be considered. Examples of other possible hazards in seaweed discussed in the literature are Norovirus, Vibrio, Clostridium spp., Aeromonas spp., E. coli, S. aureus, Hepatitis A virus, Hepatitis E virus, Campylobacter spp., Shigella spp., yeast and moulds, various toxins, anti-nutrients, persistent organic pollutants, microplastic, radionuclides, nickel, aluminium, dioxins, polychlorinated biphenyls, brominated flame retardants, polycyclic aromatic hydrocarbons, fluorine, pesticide residues, pharmaceuticals, micro-and nanoplastics, and perfluoroalkyl substances.

It should be borne in mind that data on food hazards in seaweed are currently sparse. Knowledge about food safety in seaweed is increasing, but more data is needed to enable proper risk assessments. The type, level, and ranking of food hazards in seaweed in Nordic countries may change in the future, as more research produces new data, and conditions may be affected by climate change, such as increased sea temperature. New seaweed species may also be introduced into Nordic waters.

The data on heavy metals and iodine in seaweed collected from the Nordic countries, is limited. For most seaweed species several samples have been analysed, but for some, only very few. The amount of data will increase considerably when the data collected from the EU monitoring becomes available.

The fast-developing seaweed market in the Nordic countries is in an innovative phase, and the level of consumption of seaweed products is not yet known but is probably increasing. The lack of data on both food hazards and consumer intake makes it difficult to perform proper risk assessments that include both consumption and levels of hazards.

The EU Commission has asked EFSA to deliver a scientific report by 2022, with a consumer exposure assessment for arsenic, cadmium, lead, mercury, and iodine in seaweed, and also an overview of the available occurrence data of these components.

Legislation on seaweed for use as food is sparse, both globally and in Europe. In risk management and future development of regulations and standards on food safety of seaweeds, it is important to take into account the biology and the properties of these organisms.

Compared to other organisms used as food, such as terrestrial plants like vegetables, fruits and mushrooms, seaweeds have different properties and growth environments and might also differ in terms of bioavailability of the food hazards. In addition, seaweed may be consumed in different amounts and patterns than other foodstuffs. The great variation between seaweed species, the effect of age, growing conditions, and processing methods on the levels of food hazards should also be considered.

The authors of this report strongly recommend development of a harmonised legislation on food safety in seaweed, in which seaweed should be classified as a specific group of foodstuffs, with subgroups for different seaweed species.

In the near future, the EU Commission is expected to evaluate risk management options for heavy metals and iodine in seaweed. This work will be welcomed by the food authorities in Denmark, the Faroe Islands, Iceland, Norway, and Sweden.