This page covers the general food safety framework as it applies specifically to algae: contaminant limits, microbiological criteria, and the algae-specific hazards that distinguish algal food safety from that of conventional foods. It builds on the horizontal hygiene framework covered in Production, Processing and Hygiene — General and should be read alongside Novel Food, since safety data is also central to novel food authorisation dossiers.

Algae present several food safety hazards that are either unique to algae or considerably more significant for algae than for conventional food crops. Understanding these is essential context before looking at the specific contaminant limits below. A very good survey of Chemical and microbiological contaminants in algae for food is in a workgroup report in EU4algae project.

Cyanobacteria — commercially the most important group being Limnospira (Spirulina), Aphanizomenon and others — are capable of producing a range of toxins collectively known as cyanotoxins. These include microcystins (hepatotoxic, produced by various genera including Microcystis and, under certain conditions, contaminating cyanobacteria co-occurring with cultivated species), anatoxins (neurotoxic), and cylindrospermopsin (cytotoxic). This is a hazard with no close analogue in conventional terrestrial food crops, and is the most distinctive food safety issue specific to algae as a food category.

The risk arises in two main ways:

• Contamination of cultivated cyanobacteria by toxin-producing strains, particularly when cultivation water sources (lakes, open ponds) are shared with or exposed to wild cyanobacterial blooms.
• Misidentification or mislabelling, where a product sold as a edible cyanobacterium (e.g. Spirulina/Limnospira) is in fact contaminated with or substituted by a different, toxin-producing species — a known issue with some wild-harvested or poorly controlled supply chains, particularly for products sourced outside the EU.

There is currently no harmonised EU maximum level specifically for cyanotoxins in food, although EFSA has published scientific opinions assessing the risk and the German Federal Institute for Risk Assessment (BfR) and French food safety agency (ANSES) have both issued guidance recommending maximum microcystin levels in Spirulina-based food supplements (commonly cited informal benchmarks are in the range of 1 µg microcystin-LR equivalent per gram of dry product, though this is not a binding EU-wide limit). Producers and buyers commonly test for microcystins as part of batch quality control even in the absence of a binding EU limit, and several national authorities have taken enforcement action against products found to contain elevated cyanotoxin levels. This is an area of EU law still under active development; see Regulatory Cases and Precedents for documented cases.

Brown seaweeds in particular (kelps, Laminaria, Saccharina, Undaria) can bioaccumulate iodine to very high concentrations, occasionally exceeding 1% of dry weight. Excessive iodine intake can cause thyroid dysfunction. This is a well-recognised, algae-specific nutritional safety concern that has prompted specific EU monitoring guidance (see below).

Algae, particularly seaweeds, can bioaccumulate heavy metals (cadmium, lead, mercury) and arsenic from their growing environment at higher levels than typical terrestrial vegetables. Arsenic in seaweed is present predominantly in organic forms (arsenosugars), which are of much lower toxicological concern than inorganic arsenic, but the proportion of inorganic arsenic varies by species and growing conditions, making this a specific analytical and regulatory challenge for the sector.

Macroalgae, particularly when wild-harvested, can be associated with marine biotoxins more commonly associated with shellfish (e.g. from harmful algal blooms in the surrounding water), although this risk is generally lower for macroalgae than for filter-feeding shellfish. Monitoring of harvest areas is relevant where seaweed is harvested from waters also monitored for shellfish biotoxin risk.

Regulation (EU) 2023/915 of 25 April 2023 on maximum levels for certain contaminants in food, OJ L 119 5.5.2023, p. 103 EURlex repealed Regulation (EC) No 1881/2006 of 19 December 2006 on the same topic, OJ L 364, 20.12.2006, p. 5. EUR-Lex. This regulation changes frequently (on average, more than twice a year).

Relevance to algae: This is the central regulatory framework that sets binding maximum levels for contaminants in food, and it has been progressively amended to add algae-specific entries. Key points:

• Inorganic arsenic: maximum levels have been introduced for inorganic arsenic in certain seaweed-based foods and food supplements, reflecting the toxicological distinction between organic and inorganic arsenic species described above.
• Heavy metals (cadmium, lead): general maximum levels for food supplements apply to algae-based supplements; some amendments have introduced more specific limits for seaweed and microalgae products, given their tendency to bioaccumulate these metals.
• Mycotoxins: are regulated; they are not directly produced by algae, but might be produced during storage.
• The regulation is amended frequently as new data become available; producers should always check the current consolidated version rather than relying on a fixed list, as new algae-specific entries continue to be added.
• No harmonised limit currently exists for cyanotoxins or biotoxins from Dynoflagellates in this regulation, which remains a gap relative to the recognised risk discussed above. Cyanotoxins are regulated by the Drinking water directive (below) and Dynoflagellate biotoxins primarily occur in shellfish and are regulated by EU Regulation 853/2004 and 786/2013 (below). Limits for cyanotoxin and Dynoflagelate biotoxin content are also specified by German Federal Institute for Risk Assessment (BfR) and French food safety agency ANSES as well as in comprehensive WHO Guidelines for Drinking-Water Quality. None of these is directly applicable to algae but each of them can serve as a good guideline.

Regulation (EC) No 2073/2005 of 15 November 2005 on microbiological criteria for foodstuffs, OJ L 338, 22.12.2005, p. 1. EUR-Lex

Relevance to algae: Sets process hygiene criteria and food safety criteria for pathogens including Salmonella and Listeria monocytogenes. No algae-specific microbiological criteria currently exist; the general criteria for the relevant food category (e.g. dried herbs and spices, ready-to-eat foods, food supplements) are applied by analogy and by national competent authorities' risk-based judgement. Listeria monocytogenes maximum limits introduced for all food categories are particularly relevant for moist or minimally processed algal products.

Regulation (EEC) No 315/93 of 8 February 1993 laying down Community procedures for contaminants in food, OJ L 37, 13.2.1993, p. 1. EUR-Lex

Relevance to algae: Establishes the general principle that food containing a contaminant at a level unacceptable from the public health viewpoint, and especially at a toxicological level, must not be placed on the market, and provides the procedural basis for setting maximum levels such as those in Regulation (EC) No 2023/915 .

Commission Recommendation (EU) 2018/464 of 19 March 2018 on the monitoring of metals and iodine in seaweed, halophytes and products based on seaweed, OJ L 78, 21.3.2018, p. 16. EUR-Lex

Relevance to algae: This is a Recommendation, not a binding Regulation (see General on EU Legislation for the distinction), but it is highly relevant in practice. It recommends that member states monitor levels of arsenic, cadmium, iodine, lead and mercury in seaweed, halophytes and seaweed-based products over a three-year period, with the explicit purpose of building the evidence base for future binding maximum levels. Producers should expect that the data gathered under this Recommendation will inform future amendments to Regulation (EC) No 2023/915, and that current voluntary monitoring practice is a strong indicator of where binding limits are likely to be introduced next.

Council Regulation (Euratom) 2016/52 of 15 January 2016 laying down maximum permitted levels of radioactive contamination of food and feed following a nuclear accident or any other case of radiological emergency, OJ L 13, 20.1.2016, p. 2. EUR-Lex

Relevance to algae: Establishes maximum permitted levels of radioactive contamination applicable in the event of a nuclear accident or radiological emergency. Not algae-specific, but relevant given that marine macroalgae can concentrate certain radionuclides from seawater, a consideration that has been practically relevant following historic events (e.g. post-Fukushima import controls on seaweed from affected regions, applied by trading partners including the EU).

Directive (EU) 2020/2184 of 16 December 2020 on the quality of water intended for human consumption, OJ L 435, 23.12.2020, p. 1 EURlex

Relevance to algae: High-quality, safe and sufficient drinking water is essential for public health and well-being. Besides consumption, it is also used for many other purposes, such as washing, cleaning, hygiene, or watering our plants, and frequently also algae cultivation. The directive defines access to high-quality drinking water. Main objective is to ensure that water intended for human consumption can be consumed safely.

The Drinking Water Directive seems to be the only place in EU regulation that mentions cyanotoxins (specifically microcystin-LR) and defines the allowed concentration. Although not directly applicable, this limit may also be used “mutatis mutandis” as an intake limit for algal biomass.

EFSA has published several scientific opinions directly relevant to algae food safety, including assessments of cyanotoxin risk, dietary exposure to iodine from seaweed consumption, and arsenic speciation in seaweed. These opinions, while not legally binding themselves, are the scientific basis referenced when the Commission considers new or amended maximum levels. See General on EU Legislation for more on EFSA's role, and Specialised Sources — Bibliography for a list of key EFSA opinions relevant to algae.

• Test for cyanotoxins as standard practice for any cyanobacterial product (Spirulina/Limnospira and similar), even though no binding EU limit yet exists — national authorities can and do take enforcement action based on general food safety provisions (Regulation (EC) No 178/2002, Articles 14–15) even without a specific numerical limit.
• Monitor iodine content for seaweed-based products, particularly where the product is marketed for regular or high-volume consumption, given the absence of a binding limit but clear nutritional risk and known regulatory attention (Recommendation (EU) 2018/464).
• Distinguish organic and inorganic arsenic in analytical testing rather than reporting total arsenic alone, since the regulatory limits and toxicological significance differ substantially between the two.
• Track the source water and growing conditions for any product where bioaccumulation of heavy metals, iodine or radionuclides is plausible, as due diligence supporting safety claims and as a defence in the event of an official control finding.
• Stay alert to frequent amendment of Regulation (EC) No 2023/915, as new algae-specific maximum levels are added on an ongoing basis.

See also: Novel Food | Food Supplements | Production, Processing and Hygiene — General | Feed | Regulatory Cases and Precedents

Last reviewed: June 2026.