Are ferric phosphate slug pellets really safer?

The Jan/Feb issue of Which? Gardening calls into question the claims that ferric phosphate slug pellets, which are approved for use by organic growers, are really safe for pets and wildlife.

Slug pellets made with ferric phosphate contain chelating agents to make the iron more soluble and thus toxic to slugs.

Which? reports research by Dr Kathy Lewis head of the Agriculture and Environment Research unit at the University of Hertfordshire. She says, “Without chelating agents, the slug pellets would not kill slugs. The chelating agent releases the iron molecules and the slug then essentially dies of iron poisoning”

There are two risks says Dr Lewis, “Iron is toxic to many species, including humans, domestic pets and birds.” She goes on to say, “One of the chelating agents, EDTA, is also toxic… particularly to earthworms and this is not good news for gardeners.”

The magazine concludes that there isn’t much to choose between metaldehyde and ferric phosphate pellets. Neither should pose a danger if used according to manufacturer’s instructions.

Which? mentions also that new ferric phosphate pellets that do not contain chelating agents are soon to appear on our shelves, including some from Doff. But what other ingredients they contain has not been disclosed.