Think you're not seeing the forest through the trees here. Yes, people commit suicide. How many of them do it where they work? The fact that you're championing "only" 4 at work suicide attempts is a bit disconcerting. I've been working in a place of business for over 17 years. Not once has some one tried to kill themselves at work, let alone 4 attempts in one year.
First of all, they do it at their workplace because they live at their workplace in company dormitories. They don't go anywhere else, it's like company towns found anywhere else in the world when industrialization occurs.
Secondly, these are very big workplaces. I'm sure your place of business does not have anywhere near the numbers of people that work at these operations.
Third, the suicide rate among any population of a large enough sample is going to be greater than zero. It's just a fact of life that some people kill themselves, and their reasons for doing so are as diverse and complicated as people are. The fact that suicide rates at Foxconn are lower than the Chinese population as a whole is the forest you're looking for. It says that working at Foxconn is better than the alternative. The conditions may not be up to western standards, but it's better for them to have a job under those conditions than to not have a job at all. There is only one reason for labor costs to be so low, and that is because there are far more people needing a job than there are jobs available. Suicide should not be considered in a vacuum. Suicide, when taken into account as just one cause of death among many, should be weighed against starvation, disease, and homelessness those workers are not suffering from as a result of their Foxconn employment. Foxconn offers a clear net good, and workers there are not only elevating themselves, but giving their future generations a leg up towards middle and upper class living. Yes, some are going to kill themselves. Some are going to get AIDS, too, or get hit by a train. We should not blindly ascribe all causes of death to one's employer, at Foxconn, in China, or anywhere else. Instead, look at the actual statistics, and see that Foxconn employment correlates to a lower rate of suicide. Working at Foxconn does not make people want to kill themselves, it makes people not want to kill themselves.
Using your iPhone should not fill you with white liberal guilt, it should fill you with the satisfaction that your consumerism is helping to lift people up out of poverty in a country desperate for jobs. If we make enough iPhones and iPads in China, eventually the Chinese workers will have enough money and living standard expectations that the conditions will improve, labor costs will increase, and our iPhones and iPads will have to be made somewhere else. China will specialize in something other than cheap unskilled labor, and the great wheel of macroeconomics will continue to turn giving us all more wealth and more stuff all over the world.