From dog attacks, strangulation and rape, to injured fishermen being thrown overboard and left to drown, trafficked people can suffer extreme violence and severe health problems no matter where they end up working, researchers have found.
In the largest ever study into the health of trafficking victims, researchers interviewed more than 1,100 men, women and children in Southeast Asia who had been trafficked into at least 15 sectors - including factory work, domestic labour, sex work and fishing.
"While we all hear about the horrors of human trafficking, when you get the statistical findings like this, it tells you that these nightmares are not isolated cases or necessarily the worst of the stories that get told," Cathy Zimmerman, one of the researchers, said in an interview.
Most previous studies looked at the health of women trafficked into sex work.
What this study found was that women trafficked for other forms of labour, including factory work, domestic work and as brides, suffered worse mental health problems than those trafficked into sex work.
They were more likely to suffer from post-traumatic stress disorder and high levels of anxiety, Zimmerman told the Thomson Reuters Foundation.
Men trafficked as fishermen worked for the longest periods, about 19 hours a day seven days a week, spending on average 16 months at sea with no means of escape, Zimmerman said. One man reported being at sea for about 10 years.
Some told researchers they saw captains pushing injured fishermen overboard.
"Murders were definitely witnessed," Zimmerman said.
Domestic workers were some of the worst affected, because they were extremely isolated, often did not speak the language of the family, and were kept indoors working long hours for months or years at a time, she said.
The worst violence was reported by women trafficked as brides.
"It makes it very clear that trafficking is not just about sex work, but is about exploitation in a huge range of sectors from which a lot of us probably benefit," Zimmerman said.
"We don't want workers to be out of a job, we just want them to have good working conditions," she added.
Zimmerman and others from the London School of Hygiene and Tropical Medicine joined researchers from the International Organization for Migration to carry out the study in Vietnam, Cambodia and Thailand.
The resulting report "Health of trafficked persons", was published in The Lancet medical journal on Wednesday.
About half those interviewed had been physically or sexually abused. Many had experienced extreme violence - they had been attacked with knives or dogs, burnt or strangled.
Most of the victims had worked long hours in appalling conditions, which meant injuries were common and usually went untreated. A few had lost limbs.
About 70 percent of men and women, and 35 percent of children, said they had never had any freedom.
The researchers found a lot of physical health problems, but the most common and severe symptoms were related to mental health. Depression, anxiety and post traumatic stress disorder were prevalent. Five percent said they had tried to commit suicide in the four weeks before the interview.
Study lead author Ligia Kiss, at the London School of Hygiene and Tropical Medicine, said survivors of trafficking urgently need access to healthcare, including mental health care.
Zimmerman said: "Health is one of those things that everybody always thinks somebody else is going to do because there's a 'health sector', and it's not the case with people who end up in a shelter."
"You need to have referral systems to the health system, and the health system needs to be prepared to receive people who are trafficked ... with an understanding of what trafficking means to health," she added.
Very little is known about what makes someone vulnerable to being trafficked, Zimmerman said.
"Trafficking cannot be explained by poverty alone. There are lots of poor people in the world who don't get trafficked," she said.
"There has been lots of awareness raising. But really, is it enough to say: 'Hey, if you migrate you could be trafficked'?
"What this study does, is hopefully puts numbers to the problem so that real action is taken to prevent exploitation, and resources are there to help people to recover who might fall prey to these abuses," Zimmerman said.