The report, published in the October issue of Arthritis & Rheumatism, said more than 8 million Americans suffer from autoimmune diseases, in which the immune system attacks the body’s own tissues.

A team at the Fred Hutchinson Cancer Research Center in Seattle examined death certificate data from 26 states from 1984 to 1998.

Farmers showed increased risk of death, particularly those who worked with crops rather than livestock. Several industrial occupations such as mining and textile machine operators -- as well as timber cutting and logging -- had an increased risk of death from this group of diseases, the report said.