A woman who lives on the edge of farm fields in Sussex has accused the government of failing to protect people from pesticides.
Georgina Downs claims the government's method of assessing the health risk of chemicals sprayed on crops does not address long-term rural residents.
She is asking the High Court to rule the government's approach breaches UK and European law.
Environment Minister Hilary Benn will defend the government's policy.
She told Mr Justice Collins: "I have lived next to regularly sprayed fields for over 24 years and have long-standing health problems."
Ms Downs said there had never been a risk assessment into the affects of long-term exposure to pesticides on rural residents, including pregnant women, babies and other vulnerable people.
She said the government used the "bystander" model which assumed people would only be subjected to a occasional, short-term exposure from one pesticide.
Ms Downs said that was not the reality faced by rural residents "who are repeatedly exposed to mixtures of pesticides and other chemicals throughout the year, and in many cases, like mine, for decades".
Crop sprayers were legally entitled to know what chemicals they were using and had protective equipment, which the public was denied, she said.
The court heard that Ms Downs, who lives near Chichester in West Sussex, has been pressuring the government over pesticides for several years.
The hearing is expected to last for four days.