France, Aug. 30 -- The problem creates a dangerous trade-off. While protective clothing can reduce contact with pesticides, in extreme temperatures it can also trap body heat and increase the risk of heat-related illness.

Research by the Union of Concerned Scientists (UCS), a US-based advocacy group, has documented the risks that extreme heat and pesticide exposure pose to farm workers.

In the United States, the issue is also part of a wider debate over protections for people working in extreme heat. The Occupational Safety and Health Administration, the federal agency responsible for workplace safety, has proposed the country's first federal workplace heat standard.

It would cover agriculture and other sectors, but has not yet been fi...