If you start putting used toilet brushes in the post, I will no longer accept any mail. Are you not confusing biodegradable with repair? Wooden brushes with bamboo bristles or something instead of poo post?
You do know that all sorts of unpleasant things are sent through the post, correct? A neighbor of ours when I was growing up literally shipped bull semen, that was a large part of their business.
And sewage is regularly sent through the mail as well, many municipal sewage-treatment plants ship samples to specialized labs for analysis. Toilet-brushes are far from the most disgusting things sent through the mail, and unless you clean your toilet without flushing any waste in the bowl first they aren't even that dirty. Considering the prevalence of sanitizing toilet cleaner, it wouldn't surprise me if the average brush is cleaner than the door handles of a public restroom.
