'Toxic' pesticide Dichlobenil used on London Underground
A "toxic" chemical was put on weeds on London Underground (LU) up to 18 months after European Commission (EC) guidance was given against its use, BBC London has learnt.
LU said it had done nothing wrong because after announcing the ban on using Dichlobenil, the EC gave a period of grace which meant it could be used until 18 March 2010.
But some campaigners believe, as a public body, LU should have stopped using it as soon as the EC said it was dangerous to do so.
On 18 September 2008, the EC announced Dichlobenil had been assessed for effects on human health and the environment and, "it was concluded that there are clear indications that it may be expected that it has harmful effects on human health, and in particular consumer exposure from drinking water."
The ban of authorisations for Dichlobenil came into effect on 18 March 2009, and the period of grace ended on 18 March 2010.
A Freedom of information request submitted by BBC London showed 11,925kg of a weed killer called Viking Granular - which contained Dichlobenil - was used in 2008 and 2009, and 8,925kg in 2010.
Nick Mole, from the campaign group Pesticide Action Network, said: "The reason it had its approval revoked at European level was because it was contaminating water and there was a potential human health impact with potential links to cancer.
"Certainly, as soon as it was taken out of approval they [Transport for London] should have wound it down immediately and not pushed it right up to the legal limit.
"That would have been the responsible way forward."
Gill Erskine, from the Health and Environment Alliance which looks at how the environment affects health in the European Union, said: "It can cause birth defects in rabbits.
"There have been lots of tests on rats, mice, and hamsters. And it's also been shown to cause prostate and breast cancer.
"It seems surprising that Transport for London would continue to use a chemical that's known to be toxic to our health."
Phil Ufton, from LU, said it had used the period of grace to continue to use Dichlobenil because it needed time to find an alternative weed killer.
"LU hasn't done anything wrong in terms of legislation," said Mr Ufton.
"We had to go through a trial period to determine which was the most effective solution.
"We do have an obligation to make sure that we do clear vegetation off our railways.
"We couldn't just stop using it, we had to use something."