The contaminant has been linked to the deaths of more than 300 children in Africa and Asia
Rupa Asha Huq, born to Bangladeshi migrant parents in 1972, has been a former Deputy Mayor of the London borough of Ealing Central and Acton. She is a writer and columnist and a sociology professor at Kingston University.
The 'manhandling' took place during a walkabout, as the Mayor of London was canvassing support for the local Tory candidate, Angie Bray, when Rupa Huq tried to draw him into debate about the issues facing Ealing.
Johnson and Bray can be seen striding along the pavement in pictures published by the 'Independent' when Huq is repeatedly grabbed by the activist who tries drag her away from Johnson.