Houseplant, excess fertilizer, tray has yellow stains?

I water my houseplants once a week during winter. Off late the plants have started to wilt and dry. I must have added excess fertilizer. The trays are having sticky residue which is yellow brownish in color. Is the residue a result of over fertilization? The residue can be seen on the carpet. I'm not sure how safe it is to have these plants at home any more. Would I be poisoned or get cancer if i touch those trays and pots?