In the school I work in, there is a risk of the higher needs young children eating the rock salt. Other than doing a risk assessment and ensuring that there is adequate supervision at all times, has anyone else coming across this and how are you controlling it? Have you found an alternative such as gritting school playground with EcoGrit ice melt (but I imagine this will be very expensive for schools to purchase?

When I have to clear snow at home, and at the moment I am snowed in entirely, I use normal salt. This may be a better option fpr you, as it may not be as expensive to buy in bulk, will only form salt water as a by-product and has no 'bits' that higher needs children might think are edible.

The potential down side to this as an option is that the 'bits' often give extra grip underfoot, so it may be that you need to use more pure salt than you would grit to achieve a satisfactory result...