Ingested engineered nanomaterials: state of science in nanotoxicity testing and future research needs

Area of Science:

• Nanotoxicology
• Food Science
• Materials Science

Background:

• Engineered nanomaterials (ENM) are increasingly used in food for various functions, including texture enhancement, nutritional fortification, and improved packaging.
• Safety assessment of ingested ENM (iENM) is a growing concern within the nanotoxicology field.
• In vitro monoculture cell models are commonly used for iENM safety evaluations due to cost and ease of use.

Purpose of the Study:

• To systematically review the current state of toxicological testing for iENM.
• To assess the physiological relevance, methodological strengths, and challenges of existing test systems.
• To identify future research needs and priorities for iENM safety assessment.

Main Methods:

• Conducted extensive literature searches in Google Scholar, PubMed, and Web of Science for studies on iENM safety over the last decade.
• Evaluated relevant literature based on criteria including material characterization, dispersion, dosimetry, dose realism, dissolution, and endpoints.
• Analyzed data to identify patterns, trends, and research gaps in iENM toxicity testing.

Main Results:

• Only 21% of reviewed studies used food-grade nanomaterials, and 53% provided adequate physicochemical characterization.
• All in vitro studies lacked proper dosimetry, and 60% did not justify tested doses.
• Few studies considered nanomaterial dissolution kinetics (12%) or prepared standardized dispersions (1 study).

Conclusions:

• Key factors for robust iENM toxicology include using food-grade materials, comprehensive characterization, standardized dispersions, realistic dosimetry, and assessing dissolution/biotransformation.
• Current in vitro models often lack the physiological relevance needed for accurate iENM safety assessment.
• Recommendations are provided to guide future iENM toxicity studies and develop more representative in vitro models.