The wood that is poisonous burning are woods with ivy or vines which are toxic plants and burning them releases toxins into the air.
Woods such as cherry, elder, horse chestnut, laburnum, yew, oleander and rhododendron are considered poisonous and toxic and are not meant to be burnt.
As far as harmful firewood types, driftwood contains dioxins (from the saltwater), and wood from poisonous trees and vines such as poison sumac and oleander can produce toxic smoke.
Brazilian pepper wood is also not good to burn because of the toxic chemicals.
Burning poison ivy, poison sumac, poison oak, or pretty much anything else with the word "poison" in it's name releases the irritant oil urushiol into the smoke.
There are over 100 hazardous chemicals released from wood burning that can be toxic and carcinogenic (cancer-causing).
For example, Benzene and Formaldehyde are two carcinogens released from burning wood.
Woods that are toxic to humans include.
Yew Wood.
Yew wood, while beautiful and workable, contains toxic substances that can pose serious health risks if not handled properly.
Ebony Wood.
Walnut Wood.
Rosewood.
Long-term exposure to wood smoke air pollution has been associated with an increased risk of lung cancer, as well as other types of cancer, including bladder and breast cancer.