Chronic level of exposures to low-dosed MoS2 nanomaterials exhibits more toxic effects in HaCaT keratinocytes

Molybdenum disulfide nanomaterials (MoS2 NMs) have shown significant role as photocatalysts, lubricating agents and sterilant due to their remarkable physicochemical properties. Because of the increasing demand for MoS2 NMs in numerous industrial domains, greater occupational exposure and subsequent NMs release into environment would be unavoidable. However, much efforts have been made to uncover the biological effects of NMs at unrealistic high concentration or acute duration, placing constraints on setting the realistic occupational exposure thresholds with confidence. In order to fill the current knowledge gap, this study aimed to evaluate the nanotoxicity of MoS2 NMs with or without surface defects under the more realistic exposure mode. Noteworthily, the artificial sweat transformed-occupational exposure-cytotoxicity investigation of MoS2 NMs was established as the main studied line. And the high cellular internalization and augmented oxidative stress triggered by surface defect could be recognized as the main factors for triggering serious cellular damage. Moreover, the HaCaTs exhibited loss of cell membrane integrity, dysfunction of mitochondria, disorder of endoplasmic reticulum and damages of nuclei after chronic exposure, compared with acute exposure. The study provided closely realistic exposure scenarios for NMs which exhibited significant difference from acute toxic investigation, enriching understanding towards real environmental safety of NMs. [Display omitted] •The study provided real toxic investigation of MoS2 with or without defects.•The sweat transformed - occupational exposure - toxicity investigation was established as studied line.•Higher toxicity was triggered by sweat transformed MoS2 after chronic exposure than acute exposure.•High internalization and oxidative damage caused by defect were main factors for serious nanotoxicity.•The function of main organelles and cellular defense were disturbed after occupational exposure.