Farmers defended the safety of their 'highly-regulated' pesticide use today after 35,000 people signed a Norfolk woman's petition which claimed agricultural sprays could cause health problems.

Lisa Over, from Foulsham, near Fakenham, petitioned farming minister George Eustice, asking 'that farmers should inform local people when spraying their pesticides, or to spray at night when people are not outside.'

Her petition says the 'continuous spraying of poisonous chemicals over fields near villages and homes can cause all manner of illnesses, especially with houses and villages backing onto these fields, where children and people are indiscriminately subjected to breathing in these sprays.'

The campaigner told BBC Radio Norfolk: 'From some of the message that I've managed to read, they are all saying the same thing. You can taste it, you can hang your washing out and your washing can go yellow, you can smell it, people are having breathing problems, skin problems and depression.

'It is not about people against farmers, it is people for people – and farmers need to take on board that they need to be more careful about what they are doing.'

But despite the thousands of petition signatories, farmers said there was no evidence linking sprays with health problems, as they were tightly regulated and responsibly applied – with any advance warning of their use 'impractical' in the fast-moving world of food production.

Tom Dye is the managing director of Albanwise Farming, based at Saxlingham near Holt, and also one of the East Anglian representatives on the National Farmers' Union (NFU) Combinable Crops Board. He said: 'The pesticides which farmers are able to use today have never been safer, and have never been more highly regulated and restricted than they are now.

'Farm managers have never been better advised and better trained to judge on a day-to-day basis whether they should or should not spray. The standard of training of the operator as well as never been higher, and the application technology and nozzles we use now will mitigate against any drift.

'We don't spray in a wind where we think is going to drift, particularly if it is in the direction of people or wildlife.

'Management decisions change within the space of five minutes to react to the forecast and the conditions at the time. To be able to reliably inform a large group of people is a wonderful idea, but very impractical.'

NFU East Anglia adviser Rachel Carrington added: 'There is no legal requirement on farmers to inform neighbours about planned use of crop protection products and it would be difficult to do so on all occasions because weather conditions play a significant part in determining when spraying takes place. 'This means decisions often have to be taken at short notice.

'However, we do recognise that people living in the countryside sometimes have questions about what is happening nearby, and would like to know who to speak to for answers. We've worked with other organisations to develop the Good Neighbour initiative, which sets out best practice for operators to follow when spraying near to residential areas. The NFU is also part of the Voluntary Initiative that promotes responsible pesticide use.

'If people want to find out more we'd urge them to visit one of the many farms opening to the public for Open Farm Sunday in June. Farmers would be more than happy to answer their questions about what goes on beyond the farm gate.'