Overdosing Mother Nature, Small Pond: Both scientific and anecdotal information about various drugs’ effects on human physiology bounds. But medicines also have an impact in the wild. Our bodies, homes, and factories are emitting pharmaceuticals that enter waterways and accumulate in fish, bugs, mollusks, crustaceans, birds, and warm-blooded animals. Areas around drug-manufacturing plants are hot spots for pharmaceutical pollution, as are waterways near hospitals and aging sewage infrastructure. Medicinal compounds have even been detected in remote environments, like surface waters in Antarctica. Traces of many drugs — antifungals, antimicrobials, and antibacterials — as well as ones for pain, fertility, mood, sleeplessness, and neurodegenerative diseases have been found in waterways.
While it is difficult to track medicines’ affect in the wild, toxicologists believe their influences on fauna can occur at low concentrations, and may be distinct from their impacts on humans. Lab studies of marine life have demonstrated a variety of symptoms. Amphetamines change the timing of aquatic insect development; antidepressants impede cuttlefish’s learning and memory, and cause marine and freshwater snails to peel off rocks. Drugs that affect serotonin levels in humans cause shore crabs to exhibit “risky behavior,” and female starlings to become less attractive to males, who in turn sing less. Shrimp dosed with Prozac are more likely to swim toward a light source, making them more vulnerable to predators hunting in sunlit areas. When Atlantic small salmon, called smolts, are exposed to anti-anxiety benzodiazepines they migrate nearly twice as quickly as their unmedicated counterparts, meaning the juvenile fish are likely to arrive at the sea in an underdeveloped state and before seasonal conditions are favorable.
Recent modeling shows that a platypus living in a contaminated stream in Melbourne is already likely to ingest more than half a recommended adult dose of antidepressants every day. If current trends persist, scientists estimate that by 2050 the volume of pharmaceuticals diffusing into fresh water could have increased by two-thirds. Humans can appreciate that they can affect the mental health of captive animals; now they should know they may also inadvertently be changing the mental health of wildlife.