@Bruce Woodruff I thought this pertinent: The dictionary definition of Chemical Warfare is: tactical warfare using substances with irritant, burning, poisonous, or asphyxiating properties. 

Because of its potency and low cost, drug dealers have been mixing fentanyl with other drugs including heroin, methamphetamine, counterfeit pills, cocaine, or crack, increasing the likelihood of a fatal interaction.Family sues Airbnb after 19-month-old dies of fentanyl toxicity during stay in Florida rentalEnora Lavenir died Aug. 7, 2021, one day after her family checked into an Airbnb rental https://www.nbcnews.com/news/u... 

I didn't know the PM could do an analysis for us, and hadn't thought to ask for anything like that because we kind of irritated him by asking him why the rent hadn't been paid and why the neighbors (who had to literally track us down) were contacting us about the lack of care that the yard was receiving.

Has something replaced toxic mortgage products?  

Also an irritating, ill-behaved, noisy traffic hazard.

Just a warning though, the smell of KILLZ (oil) and Polyurethane are both toxic and you will wonder for the first few days if the cure is worse than the disease.have Fun!

as for insects, litter the place with diatomaceous earth (makes the most sense between tenants, but can be used around humans and pets)worse problem with much contact is dry skin/rash.the powder is crushed diatomes (creature shells, chemically silica-ish) in effect it's micro shards of glass which wedge in the crevices of the exoskeletons. so bugs eventually get clumped up with the stuff and can't move. and sometime pierces the innards. so either way they die.it's organic, non toxic. just don't wallow in it, and don't let kids/pets play in it.

However, they didn't accept my explanation and got irritated because it seemed that I didn't 'trust' them, by the way I have a good relationship with them. 

You may want to warn your tenants that their counter top may be toxic.

I have found that humanizing the checkout procedure is less irritating to those guests who believe they should not have to clean up after themselves.