Health Risks of Nanos in Food

Health Risks of Nanos in Food

By AVICENN Team – Last Modified January 2023

Reasons for concern about the ingestion of nanos

Studies have shown that nanomaterials can:

• cross the oral and intestinal barriers and spread throughout the body¹See for example:
  - Quantitative biokinetics of titanium dioxide nanoparticles after oral application in rats (Part 2), Kreyling WG et al., Nanotoxicology, 11(4):443-453, May 2017: the authors observed the passage of the gastrointestinal barrier for a low fraction of TiO2 in the rat (0,6% of the administered dose), which is found after 7 days accumulated in different organs, mainly the liver, lungs, kidneys, brain, spleen, uterus and skeleton (cited by the HCSP in its report Review of knowledge relating to the effects of titanium dioxide nanoparticles (TiO2) on human health; characterization of population exposure and management measures, April 2018)
  - Food additive E171: the first results of oral exposure to titanium dioxide nanoparticles, INRA, press release, January 20, 2017 and E171: a danger identified in rats, a risk to be assessed in humans, INRA Sciences & Impacts press release, February 1, 2017: Food-grade TiO2 impairs intestinal and systemic immune homeostasis, initiates preneoplastic lesions and promotes aberrant crypt development in the rat colon, Bettini S et al., Scientific Reports, 7:40373, published online January 20, 2017
  - Pharmaceutical/food grade titanium dioxide particles are absorbed into the bloodstream of human volunteers, Pele et al., Particle and Fiber Toxicology, 12:26, September 2015
  - Oral exposure to titanium dioxide (TiO2) nanoparticles: from crossing the oral and intestinal epithelium to fate and effects in the body, Bettini S and Houdeau E, Biology today, September 2014
  - Titanium dioxide nanoparticle impact and translocation through ex vivo, in vivo and in vitro gut epithelia, Brun E et al., Particle and Fiber Toxicology, 11:13, 2014
  - Size and surface charge of gold nanoparticles determine absorption across intestinal barriers and accumulation in secondary target organs after oral administration, Schleh C et al., Nanotoxicology, 6(1), 36-46, 2012
  - Nano- and microparticulate drug carriers for targeting of the inflamed intestinal mucosa, Collnot EM et al., J Control Release, 161, 235-46, 2012
  - Origin and fate of dietary nanoparticles and microparticles in the gastrointestinal tract, Powell JJ et al., J Autoimmune, 34, 226-33, 2010 ; studies have also shown that silica or silver nanoparticles agglomerate in water or in acidic environments (such as the stomach) but reindividuate in the intestine where the pH is neutral; they can then more easily cross the intestinal barrier²See our file The entry points, fate and behavior of nanomaterials in the human body?,veillenanos.fr.

• then accumulate in the organs³Nanotechnologies and nanoparticles in food and feed, Afssa (now ANSES), March 2009: the digestive tract, liver and spleen are the main target organs. After oral administration of 60 nm silver nanoparticles to rats for 28 days, silver was found in the stomach, kidneys, liver, lungs, testicles, brain and blood: see Kim, JS et al. Twenty-eight-day oral toxicity, genotoxicity, and gender-related tissue distribution of silver nanoparticles in Sprague-Dawley rats, Inhale. Toxicol., 20 (6), 2008 (digestive tract, liver, spleen but also stomach, kidneys, lungs, testicles, brain), in the blood and inside the cells ;

• cause disturbances or even deleterious effects, in particular on the intestinal microbiota⁴See for example:
  - A systematic review on the effects of nanomaterials on gut microbiota, Utembe W et al., Current Research in Microbial Sciences, 3, 100118, 2022
  - Nanoparticles in the Food Industry and Their Impact on Human Gut Microbiome and Diseases, Ghebretatios, Metal., Int. J.Mol. science., 22(4):1942, 2021
  - Impacts of foodborne inorganic nanoparticles on the gut microbiota-immune axis: potential consequences for host health, Lamas B et al., Particle and Fiber Toxicology, 17:19, 2020 :

In addition to the health repercussions of ingesting nanoparticles, it should be noted that environmental risks are also poorly understood and of concern.

Many scientific uncertainties

Much is still unknown today about the repercussions that the ingestion of nanomaterials can have on human health. Oral nanoparticle toxicity studies are rare and many may have had methodological weaknesses that make it difficult to use their results. The experimental conditions still poorly reflect the way consumers are exposed; the nanomaterials considered are often synthesized in the laboratory and therefore different from the nanomaterials (and nanomaterial residues) that consumers actually ingest. Furthermore, the physico-chemical characteristics nanoparticles tested and their interactions with the food matrix are insufficiently documented. Nevertheless, progress has recently been underway, thanks to improvements in researcher practices, tools and protocols.

The complexity of assessing the risks associated with the ingestion of nanomaterials

One of the problems that is likely to persist, however, relates to the great complexity of the risk assessment related to the ingestion of nanomaterials : the toxicity of nanoparticles differs according to their physico-chemical characteristics (size, shape, degree of agglomeration, etc.). However, these characteristics are very variable according to the nanomaterials and can evolve throughout their life cycle :

• depending on the conditions under which the nanomaterials are synthesized, stored, possibly coated;
• by the transformations they undergo during cooking and the preparation of dishes or in the digestive tract²¹Mammalian gastrointestinal tract parameters modulating the integrity, surface properties, and absorption of food-relevant nanomaterials, Bellmann S et al., WIREs Nanomed Nanobiotechnol. 2015 (for example in contact with the acid medium of the stomach, etc.)
• during interactions with the packaging and/or with the other ingredients and chemical substances with which the nanomaterials are found mixed (before then during ingestion and digestion); one can fear, for example, a “cocktail effect” with certain other synthetic molecules²²Nanomaterials, combined with other substances, could become (more) dangerous? Toxicologists often work by isolating substances, which makes it impossible to establish the interaction effects of a plurality of substances entering the body..

The risk assessment must also take into account:

• individual susceptibility (stress increases intestinal permeability to xenobiotics, for example)²³See also E. Houdeau (INRA), “Nanoparticles and the intestinal barrier: understanding the crossing mechanisms”: Slideshow, Agronomic Innovation Crossroads (CIAG), November 2012; Academic article, Agronomic Innovations, 24, 105-112, 2012 ;
• duration and period of exposure²⁴Susceptibility of Young and Adult Rats to the Oral Toxicity of Titanium Dioxide Nanoparticles, Small, 9(9/10), 2013, knowing that according to a recent study, children consume two to four times more titanium than adults due to the ingestion of sweets with high levels of titanium dioxide nanoparticles²⁵Titanium Dioxide Nanoparticles in Food and Personal Care Products, Weir A. et al., About. Science. Technology., 46 (4), pp 2242-2250, 2012

Since 2009, a broad consensus on the need to strengthen research on the risks associated with ingested nanos

In 2009, the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO) convened a meeting of experts on the impact of nanotechnology on food safety: the investigation report which resulted from it, published in 2011, lists the research needs to better assess the risks in the field. 

Since 2009, ANSES has called for improving knowledge of the dangers and consumer exposure to nanomaterials. In October 2016, ANSES was contacted by its supervisory ministries to study the risks associated with nanoparticles in food, and more specifically:

• carry out a detailed study of the agri-food sector with regard to the use of nanos in food,
• prioritize the substances and/or finished products of interest according to relevant criteria determined during the expert appraisal,
• carry out a review of the available data (toxicological effects and exposure data)
• and depending on their availability, study the feasibility of a health risk assessment for certain products.

A "working group" ("WG nano food") composed of independent experts was set up in 2017. The first results of the expertise, initially expected by the end of 2017²⁶Response to question N° 85181 from MP Yves Daniel, Ministry of Social Affairs, Health and Women's Rights, October 2016; See as well ANSES is calling for applications from scientific experts to set up a "Nanos & Food" working group (WG), ANSES, January 2017, were published in mid-2020 in a report identifying food products containing (or likely to contain) nanomaterials²⁷See ANSES, Nanomaterials in food products; Collective expert reportMay 2020.
In 2021, ANSES published a second report: a specific guide to assess the health risks of nanomaterials in food complementary to investigation report on the same subject published a few months earlier by the EFSA.

At the end of 2022, ANSES published its opinion and report on the risk assessment of the nanometric fraction of the food additive E171 which points to the lack of toxicological data available to carry out a complete assessment of the additive E171 and recommends limiting the uses and exposure of workers and consumers to nanomaterials, “by promoting the use of safe products, devoid of manufactured nanomaterials, and by limiting these uses to those ultimately considered to be duly justified and subject to a documented demonstration of the acceptability of the risk”.

Notwithstanding the broad consensus on the need to strengthen research on the risks associated with ingested nanomaterials, which is still limited today.

Pending conclusive evaluations, the marketing of food products containing nanoparticles continues

In the meantime, consumers therefore continue to ingest nanoparticles of titanium dioxide, silica, silver, etc., most often without knowing it, lack of application by the industry of the labeling obligation !

En presenting his guide to risk assessment of nanos in food (2021) as well as his opinion and report on the risk assessment of the nanometric fraction of the food additive E171 (2022), ANSES recalled "the need to limit the exposure of workers, consumers and the environment to nanomaterials" and recommend “to favor safe products, devoid of these substances”.

Certainly, the additive E171 containing titanium dioxide nanoparticles has been banned in food in France in 2020 and in the European Union in 2022, but it remains authorized for the moment in medicines and cosmetics (or, in toothpaste or lipsticks and lip balms for example, it is likely to be ingested ).

Given the dangers, calls for caution and the precautionary principle 

Government recommendations on nanos in food

In front of many uncertainties concerning the risks of nanos in food, many public or para-public organizations have issued recommendations concerning the use of nanomaterials or nanotechnologies in the food sector²⁸See in particular the numerous reports from the public authorities listed in our bibliography. Among the most comprehensive reports is theOpinion on the ethical issues of nanotechnology in the agri-food sector of the Commission de l'éthique en science et en technologie du Québec published in 2011, with nine concrete recommendations that give a good overview of the recommendations issued by various actors in other frameworks, with the advantage of being relatively well articulated here and almost complete..

These recommendations can be schematically summarized as follows:

• carry out a scientific and technological watch on nanotechnological applications in the food industry and the associated risks;
• deepen research on risks ;
• inform the public;
• consult the population;
• develop the interministerial exchange of information on the state of scientific knowledge on risks;
• to allow the public evaluation of the innocuity and the legal framework of the products concerned;
• demand transparency from manufacturers andlabeling of the products concerned.

NGOs have called for a moratorium on nanos in food for years

Among the NGOs that have spoken out against the use of nanomaterials in everyday consumer products²⁹See among 51 actors' notebooks organizations that took a stand during the national public debate on nanotechnology of 2009-2010., various NGOs³⁰See in particular the NGO reports listed in our bibliography specifically called for a moratorium on the use of nanomaterials in food, including:

• at an international level, ETC-Group since 2004 in Canada, then Which? in the United Kingdom, Friends of the Earth Australia and the United States, As you say to USA
• then in France, from 2009 France Nature Environnement³¹See the France Nature Environnement (FNE) Actor's Notebook entitled " The urgency of controlling the risks associated with nanoparticles and nanomaterials! » and made for the national public debate on nanotechnology 2009-2010 : FNE explicitly asked for a "partial moratorium on nano-objects for non-medical use and in contact, in their normal use, for the general public, with the human body" (including food products and packaging).ou Friends of the Earth, and more recently, from 2016, Agir pour l'Environnement then AFOC in 2017.

Consumers unwilling to play guinea pigs

In a general context where consumers are increasingly suspicious of industrial food³²See for example Food: faced with doubts, Internet users organize themselves, The World, April 15, 2013, consumer reluctance and distrust of nanoparticles in food are growing. In general, consumers expect more transparency and do not want to be “nano-food guinea pigs”³³Nanotechnologies: all nano-food guinea pigs?, Basta!, January 14, 2010, which they already are, reluctantly, since our food already contains nanomaterials – and not only “virtual” nano objects like those used at INRA for the study mentioned above carried out in 2011.

Since 2016, the petition "Stop nanoparticles on our plates!" » launched by Agir pour l'Environnement, demanding a moratorium on nanoparticles in common food products, collected more than 52 signatures.

In 2011, INRA researchers concluded that"in situations of uncertainty and controversy, decision-makers should pay particular attention to participatory or deliberative modes of communication". THE'Citizen Science association has been campaigning in this regard for several years for the establishment of citizens' conventions whose recommendations should be taken into account by the authorities.

The INRA researchers add that "this communication must be accompanied by a strong policy guaranteeing the safety of nano-foods in a context of mistrust among European consumers". It remains to be determined who should bear the cost of such a security policy aimed at reassuring the population about applications whose benefits have yet to be proven and of which the agri-food industry and certain research laboratories seem to be the main beneficiaries, more than consumers: is it the taxpayers to pay or the companies hoping to profit from their commercialization ?