BANGKOK : Thai consumers and farmers have been left wondering about the safety of common herbs such as chilli and lemon grass.

This comes after authorities listed 13 everyday plants as hazardous substances - alarming farmers who frequently use them in natural pesticides.

Ginger, lemon grass, and chilli are some of the most common herbs used in Thai cooking, herbal medicine and organic farming.

Their inclusion, along with 10 other frequently used herbs, as hazardous substances has caused confusion and worry among farmers, consumers, non-governmental organisations and health advocates.

Organic farmers like Suthan Soonthornchot say that making natural pesticides from readily available natural growing plants like neem and citronella are cheaper and better for farmers' health and the environment.

Mr Suthan is dismayed at the latest move.

He said: "The 13 plants are the ones that Thais usually eat, and now we feel scared when we cook them. Some people even gave up eating them altogether. Announcing that these plants were hazardous and using a 'skull and crossbones' image has really caused me to panic."

Environmental activists are also confused, especially since the government has been encouraging farmers to grow organic crops for their taste and greater profitability.

Authorities admit that a bad choice of words - singling out specific plants as toxic or hazardous - has caused undue controversy.

Wichar Thitiprasert, director, Agricultural Regulations Office, said: "The aim or objective is just to control the chemical, not the plant itself." They said the plants themselves are perfectly safe, but concentrated plant extracts contain strong chemicals that could be harmful if not used properly.

And moving the 13 types of plants from Category 2 to Category 1 under the Hazardous Substances Act means they will be less regulated, not more. This is in line with organic farmers' requests and the government's own policy of supporting low impact and organic farming.

Mr Wichar said: "We want to encourage them to produce (natural pesticides) and we want the farmers to have alternatives by not just buying the synthesised chemicals from the shop. They have an alternative to select, if they want to buy a natural substance."

The Agriculture Ministry said it intends to clear up any remaining misconceptions in a public forum, as well as through a public campaign.