Are cellulose nanocrystals harmful to human health? The answer might depend on the route of exposure, according to a review of the literature by Associate Professor Maren Roman. But there have been few studies and many questions remain.

Writing in the journal Industrial Biotechnology, Roman pointed out discrepancies in studies of whether cellulose nanocrystals are toxic when inhaled or to particular cells in the body. She said that more studies are needed to support scant research results that the nanocrystals are nontoxic to the skin or when swallowed.

Cellulose nanocrystals are produced from renewable materials, such as wood pulp. Biocompatible and biodegradable, the low-cost, high-value material is being studied for use in high-performance composites and optical films, as a thickening agent, and to deliver medicine in pills or by injection. But before a material can be commercialized, its impact on the environment and human health must be determined.

Roman reviewed published studies about the effects of cellulose nanocrystals on the respiratory system, gastrointestinal system, skin, and cells, and found conflicting results. “The discrepancies in the results are not surprising,” she said, “considering that the studies all used different cell lines, cellulose sources, preparation procedures, and post-processing or sample preparation methods.”

She was also critical of much of the research for overlooking chemicals that may be present in cellulose nanocrystals from prior processing. “Only by careful particle characterization and exclusion of interfering factors will we be able to develop a detailed understanding of the potential adverse health effects of cellulose nanocrystals,” Roman concluded.

Read the full press release.