Chemical toilet cleaners often contain highly caustic sodium hypochlorite (chlorine), which is found in most bleaches. This pollutes rivers and ponds and destroys bacterial balance in sewage. It is poisonous to human beings and should not be breathed in. Always keep it in a locked cupboard. DO NOT mix toilet cleaners, as a dangerous gas will form.
Alternative
Use vinegar to remove lime-scale and as a disinfectant. Clean the toilet with a lavatory brush and cloth and wipe down the surrounds with vinegar and hot water.
