PAPER REPRISE: Model Estimated Safe Exposure Limits for Engineered Nanoparticles

My student Vignesh Ramchandran and I made an effort in this 2023 paper to estimate the NOAEL (No Observed Adverse Effect Level) for groups of engineered nanoparticles (https://doi.org/10.1115/1.4055157). The NOAEL is the highest dose of an exposure that produces no detectable negative effect in the subject (usually rodents). It is the basis for setting safe exposure limits for people, where it is usually reduced by a factor of between 10 and 100 due to humans’ longer lifespans and other factors.

Interestingly, we identified clusters of nanoparticles that displayed similar combinations of effects with a regression tree model, and estimated NOAELs between 20 and 16,000 micrograms/kilogram for 8 clusters of metal oxide nanoparticles. Uncertainty remains an issue given the data available at the time, but seeing several orders of magnitude difference from one cluster to the next suggests that we might not want to treat all these nano-substances as the same thing when creating regulatory limits.