Nanomaterials (NM) are substances that have at least one dimension in the nanoscale (1-100 nm). In the food industry, nanomaterials can have a multitude of uses. Nanomaterials can be used as food ingredients or dietary supplements that aim to increase absorption, or targeted nutrient delivery. Nanomaterials may also be used to enhance the physical and sensorial properties of a food product, or as a manufacturing aid.
The FDA recommends assessing the safety of nanomaterials on a case-by-case basis, stating that, “there are no food substances intentionally engineered at the nanometer scale for which there are currently enough safety data to consider their use as GRAS” (Amenta, 2015).[1] A change in manufacturing practices to modify a GRAS substance to the nanoscale requires testing to assert safety-in-use of the nanosized substance by a panel of qualified experts.
Considerations in the safety assessment of NMs arise from their physico-chemical properties. Their small size allows them to have a wider distribution, retention and closer interaction with biological systems than larger particles. Due to this small size, NMs may be retained in many cells and organs to a greater extent than larger particles of similar food ingredients. These factors impact systemic exposure and, therefore the toxicological profile of NMs, potentially resulting in new and unique safety concerns not shared with their macro-brethren.
A safety assessment must be initiated with a pre-biological physico-chemical characterization. In addition to describing the chemical composition by providing an applicable chemical formula, defining a source (when a food substance is of natural biological origin), and determining impurities and contaminants profile, physical properties are important to assess including, but not limited to melting and boiling points, specific gravity, refractive index, optical rotation, pH, solubility, reactivity, particle size, size distribution, surface area, surface charge, agglomeration potential, chromatographic, spectroscopic and spectrometric characteristics (U.S. Food and Drug Administration (2014) Guidance for Industry: Assessing the Effects of Significant Manufacturing Process Changes, Including Emerging Technologies, on the Safety and Regulatory Status of Food Ingredients and Food Contact Substances, Including Food Ingredients that Are Color Additives).[2]
Characterization of NM toxicological potential includes a diverse array of both in vitro and in vivo tests that need to be performed, in light of how NM physico-chemical properties impact the test systems.
In vitro tests include cytotoxicity assessment and assessment of metabolic activity of cells. Additionally, genotoxicity assays can also be performed in vitro to evaluate mutagenic and clastogenic potential. Challenges to in vitro genotoxicity test systems include limited nanomaterial diffusion across the bacterial cell and lack of bacterial endocytic ability for the Ames test (OECD 471) and NM interaction with cytochalasin B affecting the in vitro micronucleus assay (OECD 487). Recommendations for in vitro genotoxicity assessments include extensive dose-response investigations relating dose to physiologically relevant levels when possible and avoiding excessively high doses; justification of dose selection with toxicity and cytotoxicity data; assessment of NM exposure to the target tissue cells; use of the micronucleus test adaptations instead of the Ames test and the use of the HPTR forward mutation (OECD 476) assay to evaluate mutagenic potential (Doak, 2012).[3] Correlative in vivo genotoxicity tests, such the COMET, pig-a and in vivo micronucleus assays, also are recommended to help assess misleading positive results and potential effects of chronic exposures (ENV/JM/MONO, 2014).[4]
The need to perform in vivo safety testing should be evaluated based on individual product characteristics. Determining the amount of a food substance that can be consumed involves the application of a safety factor to a “no observed adverse effect level” (NOAEL). This NOAEL is obtained by performing in vivo safety studies. FDA recommends conducting a comprehensive toxicology assessment, based on Red Book guidance (Redbook 2000, 2007) and standard guidelines.[5] Safety assessments, using in vivo testing outcomes, should be performed in light of toxicokinetic investigations, organ and systemic NM distribution and elimination as well as bioavailability data. In certain instances, additional studies may be warranted on a case-by-case basis when toxicological endpoints, such as risk of alloimmunization, may not be addressed using the standard guidelines.
Guest Author: Odete Mendez, DVM, Ph.D., DACVP, DABT
Director of Toxicology and Pathology
Product Safety Labs
With over 40 years of experience, Product Safety Labs is a leader in providing the Food Additive & Dietary Supplement industry with toxicology, pharmacology and analytical chemistry services. We have helped many Sponsors develop data required to achieve Generally Recognized as Safe (GRAS) status for products and supported regulatory submissions to worldwide agencies.
Product Safety Labs has developed expertise in the measurement of specific nutrients in foods by conducting hundreds of PER, PDCAAS and bio-availability tests.
More information about Product Safety Labs can be found at http://www.productsafetylabs.com/.
References
[1] Amenta V, Aschberger K, Arena M, Bouwmeester H, Botelho Moniz F, Brandhoff P, Gottardo S, Marvin HJ, Mech A, Quiros Pesudo L, Rauscher H, Schoonjans R, Vettori MV, Weigel S, and RJ Peters. (2015) Regulatory aspects of nanotechnology in the agri/feed/food sector in EU and non-EU countries. Regul Toxicol Pharmacol. 73(1):463-76.
[2] U.S. Food and Drug Administration (2014) Guidance for Industry: Assessing the Effects of Significant Manufacturing Process Changes, Including Emerging Technologies, on the Safety and Regulatory Status of Food Ingredients and Food Contact Substances, Including Food Ingredients that Are Color Additives. Accessed June 15, 2016: http://www.fda.gov/RegulatoryInformation/Guidances/ucm300661.htm
[3] Doak SH, Manshian B, Jenkins GJ and N Singh. (2012) In vitro genotoxicity testing strategy for nanomaterials and the adaptation of current OECD guidelines. Mutat Res. 745(1-2):104-11.
[4] ENV/JM/MONO (2014) 34 Genotoxicity of manufactured nanomaterials: report of the OECD expert meeting
[5] US FDA Toxicological Principles for the Safety Assessment of Food Ingredients. (2007) Redbook 2000.