Australian honeys are the most contaminated in the world with natural poisons linked to chronic disease including cancer, according to international researchers.

Pregnant and breastfeeding women in particular should be wary, experts say, with unborn and breastfed infants at higher risk of organ damage from such toxins.

The news affects varieties of honey sold by many leading brands and widely available on supermarket shelves. While the products do meet more relaxed Australian food safety standards, all but five Australian honeys tested had more contaminants than the European Food Safety Authority would consider safe or tolerable, the research published in the Food Additives and Contaminants scientific journal shows.

The Australian Food Code bans the use of poisonous weeds such as Paterson's curse (also known as Salvation Jane) and Fireweed in human food. Their flowers are laced with chemicals called pyrrolizidine alkaloids that are considered the most common cause of poisoning in humans and livestock worldwide.