Poultry workers in the US are routinely being denied toilet breaks to the point they are forced to wear nappies at work, a report by Oxfam America has found.
Staff on production lines for major suppliers are mocked, ignored and made to feel fearful they will lose their jobs when they ask to got to the toilet, the study found, after interviewing workers for three years.
"Too many workers tell stories about urinating on themselves, or witnessing coworkers urinating on themselves," it said.
Some have "made the uncomfortable decision to wear adult diapers to work" to avoid having to ask to leave the production line and risk punishment, the report said.
As well as resorting to wearing nappies, employees "restrict intake of liquids and fluids to dangerous degrees."
Women who are menstruating or pregnant have been prevented from using the toilet, workers said.
The report found that when staff are allowed to use the toilet during their lunch break, they are forced to wait in long queues.
Oxfam America named Tyson Foods, Perdue Farms, Pilgrim's Pride and Sanderson Farms as the employers in the report.
Most of America's big chicken farms are based in the southern states of Texas, North and South Carolina, Arkansas, Mississippi, Alabama, Georgia, Virginia and Tennessee and employ around 250,000 people.
Tyson Foods told NBC News: "We're concerned about these anonymous claims and while we currently have no evidence they're true, are checking to make sure our position on restroom breaks is being followed and our Team Members' needs are being met."
Perdue Farms said employees receive two 30-minute breaks during each eight-hour shift.
"If an associate has a health or other reason why they need more frequent restroom breaks, they can visit the onsite Wellness Center for support services or talk with Human Resources to request an accommodation for their condition," it said.
Pilgrim's Pride called the health and safety of its employees "core to who we are as a company" and said the Oxfam claims, if true, would be "clear violations of company policy."
The National Chicken Council and the US Poultry and Egg Association called Oxfam's report into question: "We're troubled by these claims but also question this group's efforts to paint the whole industry with a broad brush based on a handful of anonymous claims," it said
"We believe such instances are extremely rare and that US poultry companies work hard to prevent them."