When we take medication, some can pass through us intact and go down the toilet. Once in the sewers, these drugs are not removed during the treatment process, and end up in the waterways. To find out how pharmaceutical waste finds its way into aquatic creatures, Erinn Richmond at Monash University in Australia and her colleagues sampled flies, beetles, other insects and spiders from six waterways in the greater Melbourne region. Overall, the group detected 69 medications in the invertebrates. Organisms near wastewater plants contained the highest levels, but low levels were also detected in those from more pristine areas. Richmond presumes river-borne pharmaceuticals probably accumulate in flies and beetles while they are underwater larvae, then transfer to spiders that feed on them after they emerge as adults. Other predators in the food web such as fish, platypuses, birds, bats and frogs may also become cross-contaminated, she says. Her team calculated that trout and platypuses feeding on insects near wastewater plants would consume anti-depressant doses up to half the level normally prescribed to humans. The impacts of this are not certain, but previous studies have found that high-level exposure to anti-depressants causes fish to become less vigilant about avoiding predators. Male birds also seem to sing less to females when exposed to the drugs.