No Stupid Questions

There was a theory a while back that Napoleon died from arsenic poisoning due to the damp Mediterranean climate causing the decay of a green wallpaper using an arsenic based dye. It didn't end up being entirely true but he may have been slowly poised by environmental arsenic throughout his life. Here is an article about it.

Arsenic is a naturally occurring element in the Earth's crust as metallic crystals or combined with other elements. Being a heavy metal, arsenic bioaccumulates. That is, it builds up in the body over time, so slow poisoning is possible.

At work I learned that cyanide is actually very dangerous because it accumulates its effects. Like you have a little now and a little later, then suddenly you can't get up from bed so you call in sick. Its dangerous stuff.

Source of radiation given to someone to hold in their wallet/pocket

don't be Don, don't be Don, don't be Don

Oh thank God.

Ricin was used in Breaking Bad. Fairly easy to produce and administer.

Alcohol is a very effective slow acting poison.

Thallium was pretty famous for this until its mechanism of toxicity and antidotes were better understood. Slow acting, tasteless, odorless, colorless, symptoms weird and mimic other things. Used to be used for rat poison but the risk of accidental exposure was too high. Requires late 1800s technology.

Hey siri, remind me!

If you want long-term, look to the liver. Alcohol will destroy it over time, but so will viral hepatitis. Have you considered slow acting diseases like hepatitis or HIV? Or something intensely carcinogenic?

Am not sure if helpful, or if this would be somewhere you could visit for reference.

The Alnwick Victorian poison garden is fascinating and perhaps even has ideas for you.

https://www.alnwickgarden.com/the-garden/poison-garden/

https://en.m.wikipedia.org/wiki/Alnwick_Garden

Hope this helps. Am hoping to get to visit one day.

You could go for Paracetamol/Acetaminophen. The lethal dose is quite low and in theory low enough someone could poison someone else with it. And once symptoms set in people's livers are often beyond rescue and they die a very gruesome death unless we find a transplant organ in time.(And even then survival is not guaranteed)

And it's relatively save to use in writing as it is coated/mixed with enough bittering agent these days that it actually wouldn't work that well to secretly posing someone.

If you need something with a shorter timeframe Methanol is an option.

And of course there's always Dihydrogen monoxide-everyone who has even had one drop of it will die eventually but the time range depends on the dose. With very high doses people die in minutes,with medium doses (this is actually sometimes used by inmates to kill themselves) they die within a day, with lower dose after decades, but some die mere days after they ingested the mere last drop of it. Nasty stuff and very available.