Borax (sodium tetraborate decahydrate) is classified by the EPA as ‘not acutely toxic’ and they have stated that “there were no signs of toxicity observed during the study and no evidence of cytotoxicity to the target organ.” A further study has showed that a dose of 2g is needed to cause harm to a young child (0-4 years). The amount of borax contained in a child’s slime as made in a Fun Science party, workshop or club is roughly 0.025g and therefore does not constitute a harmful dose.
Studies have also shown that borax cannot be absorbed through unbroken skin and is not irritating to unbroken skin.
However, as a precaution we recommend that children and adults wash their hands after playing with their slime and that the slime be kept out of the reach of younger siblings and pets due to the risk of accidental ingestion.
If the slime is accidentally ingested, you should monitor your child for symptoms of feeling unwell, stomache ache, vomiting, diarrhoea, headaches and dizziness. If you observe any of these or any other unusual behaviour from your child, you should take them immediately to your local hospital’s emergency department and let them know that they have swallowed a borax containing product.
For more information visit https://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPP-2005-0062-0004