Kitchens have many things in them, and many things that can cause cancer.
Teflon:
Bad Drinking Water:
Sources used: BALCO Medical Centre, EWG.org, Naturopathy
Now, I'm saying this before putting in all the research, but, I doubt there are that many carcinogens in your bedroom. But we'll see.
Mattress:
Air Fresheners:
Source used: thehealthy
Pretty much, dogs can be affected by most things. It's not like there's any specific carcinogen, it's just all of them. If you leave out a mothball, the dog can get it; if the dog is licking the upholstry or something like that, they are licking the flame-retardant chemicals; if you do literally anything, the dog can probably get to it. A lot of it's just going to be ingestion though.
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I'm just going to pick the kitchen since that seemed like one that had a lot.
The general idea is: check things before you buy them for chemicals, and buy natural and safe kitchenware. Get spices and stuff from trusted venders who check their products for things like lead, buy cast iron or even ceramic to avoid chemicals like Teflon that are on non-stick items, and buy a water filter for your tap; things can get in the water supply and ground water, plastic bottles can leach into the water.
I've learned that there are a lot of things within your home that contain carcinogens. I've also learned that a lot of them are flame-retardants. I now know what items have carcinogens and ways to counter and avoid them.