Shoes are made of petrochemicals parts which is put together with adhesive. Final product of shoes are contained petroleum materials and solvent so that it contains Toluene, Benzene, Ethylamine which are harmful to human body. And it also contains toxic substance rom material processing process.
So, after shoes are completed to ship into containers and display
on store, the serious problem is caused by shoes emit toxic substance which has to be settled long time ago.
From production process, shoes normally laid on warehouse with high temperature and humidity which helps to grow fungus. Fungus effects final products quality badly. In case of nature leather products,
if they got fungus on surface, it has to be scrapped.
When customers wear shoes, shoes can be contaminated with sweats from human body and microbe breeding is causing bad smells.
Those factors are caused of foot related disease.