Lab hands and knowing toxic substances in Uganda

How does one know a toxic substance? Perhaps paradoxically, through contact with it, as I show ethnographically from a molecular biology laboratory in Uganda, a site where people routinely handle a range of chemicals, including potentially hazardous toxicants. I analyse an everyday situation in which researchers worked with ethidium bromide, a substance regularly used to stain DNA bands in gels at this Ugandan lab but also in many comparable labs elsewhere. Ethidium bromide is one of the most fear‐inspiring chemicals at this lab; it is considered a potent mutagen and thus counts as highly carcinogenic. While the lab has clear safety procedures concerning how to handle this substance correctly, these are often not implemented in a hard‐to‐control lab setting marked by both material deprivation and a steady flow of unremunerated volunteers who seek to gain practical experience. I show how experienced Ugandan scientists have learned to mitigate their own risk of exposure to ethidium bromide by developing choreographed routines that prevent them from inadvertently touching it. I examine this as a way of ‘handling’ a dangerous substance, developing and habituating skilled movements of hands and bodies that then are passed on to other researchers. It is not an abstract knowledge of a substance's chemical properties that counts here; instead, knowing a toxic substance implies practical routines of handling.