An eminent British cancer specialist stated that there was no evidence that the notorious defoliant, Agent Orange, was a carcinogen while he was being paid as a consultant by its manufacturer, it was reported last night.

Sir Richard Doll, the epidemiologist, whose pioneering work in the 1950s proved that smoking caused lung cancer, was receiving a consultancy fee of $1,500 a day in the mid-1980s from Monsanto, then a major chemical company and now better known for its GM crops business.

While in its pay, Sir Richard wrote to a Royal Australian Commission investigating the potential cancer-causing properties of Agent Orange, made by the company and used by the US in the Vietnam War.

According to documents seen by The Guardian, Sir Richard said that there was no evidence that the chemical caused cancer.

Millions of litres of Agent Orange — so called because it was stored in drums marked with an orange band — was sprayed on to South-East Asia. The propensity of it to cause birth defects was noticed in laboratory animals in 1969 and its use was suspended in 1971.

The chemical affected a generation of Vietnamese children born from the 1970s onwards, who showed abnormally high levels of skin diseases, cancers and congenital deformities. Other documents seen by the newspaper revealed that Sir Richard had also been paid a £15,000 fee by the Chemical Manufacturers’ Association and two other leading companies, Dow Chemicals and ICI, for a review that largely cleared vinyl chloride, used in plastics, of any link with cancers, apart from liver cancer. His conclusions were disputed by the World Health Organisation but manufacturers’ trade associations used his findings to defend the chemicals for more than a decade.

Yesterday Professor John Toy, medical director of Cancer Research UK, which funded much of Sir Richard’s work, defended his reputation.

Prof Toy said that times had changed and that the accusations needed to be put into context.

He said: “Richard Doll’s lifelong service to public health saved millions of lives. In the days he was publishing it was not automatic for potential conflicts of interest to be declared in scientific papers,” However, some scientists, including Swedish Professor Lennart Hardell, believe that Sir Richard’s work has led to the underestimation of the role of chemicals in causing cancer.

He said: “It is OK for any scientist to be a consultant to anybody, but then this should be reported in the papers that you publish.”

Sir Richard, who died last year, was revered in the medical and scientific establishment for his research that proved that the biggest lifestyle cause of cancer was smoking.

Monsanto said last night that it could not confirm how much work Sir Richard did for it butsaid he was an expert witness for Solutia, a chemical business spun off from Monsanto, as recently as 2000.

Times Recommends

• Time-worn Freddie gives up Test matches
• Brighton company 'involved in cyber attack'
• The art of survival: it’s all in the mind