Al Gore, the self-styled squeakiest-clean and deepest-green politician in American history, has some explaining to do.
His environmental organisation has taken money to raise awareness about the need for clean water from a controversial chemicals company involved in the aftermath of one of the world's worst pollution disasters.
Dow Chemical, the United States firm which now owns the leaking pesticides factory responsible for thousands of deaths in Bhopal, India, was sponsoring Live Earth events in 150 cities yesterday. The events aim to raise money for clean water programmes.
Research by environmental organisations has found dangerous levels of highly toxic chemicals in rivers, lakes and other water supplies close to several factories owned by Dow and its subsidiaries in countries including the United States, Brazil and South Africa.
Dow's factories at its global headquarters in Midland, Michigan, have been accused of contaminating the region, including the Tittabawassee River floodplains, with high levels of dioxin - one of the "dirty dozen" most dangerous chemicals.
In 2007, the highest level of dioxin contamination ever measured by the US Environmental Protection Agency was found in the Michigan Saginaw River. Residents were advised to avoid contact with river sediments and not to eat locally caught fish.
Campaigners are outraged by what they call Dow's blatant attempt to paint itself as a green company and divert attention from the Bhopal scandal, where 25 years after the 1984 disaster at the plant (then owned by Union Carbide) thousands of villagers are still forced to use contaminated water which causes birth defects, cancer and skin disorders.
Live Earth, which has accumulated celebrity supporters and thousands of activists worldwide since its climate change concert in 2007, has been criticised by campaigners for joining forces with a company which has a track record of, at best, being slow to clean up toxic spills that pollute water, damage ecosystems and endanger lives.
Three weeks ago, Amnesty International asked Live Earth to reconsider the sponsorship unless Dow publicly agreed to clean up Bhopal. Live Earth did not respond.
Dow has branched into water purification technologies. Campaigners claim the sponsorship deal is part of its wider strategy to exploit business opportunities in water scarcity.
Tim Edwards from the International Campaign for Justice in Bhopal said: "This is categorically a green-washing exercise. It is one plank of Dow's Human Element campaign which started in 2006 to clean up their image by marketing themselves as a sustainable, environmental, caring company and repair the damage caused by scandals such as Bhopal."
Dow is the sole sponsor for 24 hours of fun-runs and concerts organised by Live Earth, which hopes to create a global movement to tackle water shortages affecting one in eight of the world's population. Greenpeace, which for years has been highly critical of Dow's environmental record, refused to comment because it supports Live Earth.
Scot Wheeler from Dow said: "The sheer scale of the world water crisis requires that diverse organisations including NGOs and corporations come together to create and implement solutions ... As a founding member of Global Water Challenge and a world leader in chemistry, Dow is well positioned to provide breakthroughs and global initiatives that supply safer water to those in need."