From Fig 2. of https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7789336/

Mechanism of DNA methylation and histone modification alterations induced by nanomaterials and nanoparticles:

Exposure to NMs and NPs alters the functioning of chromatin-modifying proteins, e.g., DNA methylation and demethylation machinery, and histone-modifying enzymes, causing changes in the pattern of DNA methylation and histone modifications.

One of the most common effects of NMs and NPs is the induction of cellular stress, e.g., oxidative and endoplasmic reticulum stress, and metabolic disturbances, e.g., one-carbon metabolism and the citric acid cycle.

These events are causing DNA damage and repair response and metabolic alterations affecting the functioning of chromatin-modifying enzymes.

Any or all of these events may result in hypomethylation of DNA and altered histone modification patterns.

Additionally, exposure to NMs and NPs causes activation of the inflammatory response that, in turn, may cause DNA hypermethylation and histone modification changes