A High Court judge ruled in favour of Georgina Down's bid for a judicial review and said the Government had failed to comply with its obligations to protect rural residents and communities from possible harmful exposure to toxic chemicals during crop spraying.

Mr Justice Collins, sitting in London, said Hilary Benn, Environment, Food and Rural Affairs (Defra) Secretary must rethink the way spraying is controlled and the risks to human health assessed.

Defra had argued its approach to the regulation and control of pesticides was "reasonable, logical and lawful in all the circumstances".

But, the judge said Miss Downs had produced "solid evidence" that residents had suffered harm, raising doubts as to the safety of pesticides under the current regime.

Miss Downs, who lives on the edge of farm fields near Chichester, West Sussex, launched her independent UK Pesticides Campaign in 2001.

The judge described how she was only 11-years-old when first exposed to pesticide spraying "and began to suffer from ill-health, in particular flu-like symptoms, sore throat, blistering and other problems".

Miss Downs has collected evidence of other rural residents reporting health problems including cancer, Parkinson's disease, ME and asthma they believe could be linked to crop spraying.

She accused the Government of failing to address countryside residents such as herself, "who are repeatedly exposed to mixtures of pesticides and other chemicals throughout every year, and in many cases, like mine, for decades".

People were not given prior notification about what was to be sprayed near their homes and gardens, she complained.

In his ruling, the judge said it was interesting to note that the 1986 Control of Pesticides Regulations stated that beekeepers must be given 48 hours notice if pesticides harmful to bees were to be used.

The judge said: "It is difficult to see why residents should be in a worse position."

Mr Justice Collins said "defects" in Defra's approach to pesticide safety "contravene the requirement" of a 1991 EC Directive that harmonises the regulation of "plant protection products".

The judge ruled that the result of his judgment was that Mr Benn "must think again and consider what needs to be done".

Later, Miss Downs said she was "very pleased" with today's "very significant landmark ruling" and called on Prime Minister Gordon Brown to intervene and block any appeal.

She added: "The fact that there has never been any assessment of the risk to health for the long-term exposure for those who live, work or go to school near pesticide-sprayed fields is an absolute scandal, considering that crop-spraying has been a predominant feature of agriculture for over 50 years."