Thank you for bringing this to our attention. We’ve checked the classification of calcium carbonate in SDSs from different manufacturers as well as other sources and agree that calcium carbonate is usually not classified as hazardous under the GHS and that this is consistent with the classification given by suppliers in Australia.
We have been advised that discrepancies between classifications in SDSs etc. can be due to the manufacturers or Chemwatch using a different versions of the GHS. We are in the process of updating the classifications in the List of recommended chemicals for science in Australian schools to ensure that they reflect the Australian GHS classifications according to the Work Health and Safety legislation.