PLEASE understand that I am NOT trying to inflame any one!
BUT, let's look at the reality of life aboard a boat! If you are weekend/short vacation sailing in known first world areas, You what ever you need in small quantities you feel is required.
OR, live with a small problem during the short time aboard.
We were cruising full time (24/7) for years at a time and most of the time in some very remote areas, areas with a known large cockroach infestation.
Our option was/is to live with a large infestation or take action. Living with roaches is NOT an option for us!!!
MANY options exist to combat the bugs, some better than others, and some that are no good at all!
In that vain, we looked at and used MANY types of weapons against the buggers! We first started with boric acid, then boric acid with additives like sugar, condensed milk, cookies, etc.... The strait acid is a powder and only sits on flat surfaces and needs to be replaced often. And you breath the fumes as it's stirred up around the boat. Wash or vacuum and you need to start over.
Our video (posted in my first reply) above shows what we found works, and works well. Since moving aboard in 1996, to date, we have NO cockroaches! And we even had cardboard (from very remote stores) aboard at times.
*** LET ME RESTATE THAT, since 1996 to date – NO COCKROACHES ***
Weather a product is OK for a human to eat (as determined by the government) has NO baring on the subject. Sorry, but don't get me started on what food is safe for us, GMO & all!
The “chalk” we use is never in anything we eat! It is used to mark the sides of the hull and areas where the bugs crawl. All the sites are normally out of sight to us. AND, it stays in place for months and years and still works!!!!!!! In the years, it would have taken 10s of pounds of boric to do what one small chalk stick has done!
In the USA, we have found it in discount stores and Asian markets.
What ever a captain chooses to use, all of the option and usage should be weighed, What it is, how dangerous it is, how much is required, how often must it be used.
Sailing & cruising is dangerous in itself, we all try to lower the risk, the fuel & oil are not safe to eat, but we use them. We try to keep all unsafe chemicals out of our water, after all, it's where we live!