Every year, a “dead zone” appears in the Gulf of Mexico due to a gigantically large algae bloom. This summer, the National Oceanic and Atmospheric Administration predicted the dead zone to be the size of both Delaware and Connecticut combined.

The origins of the dead zone are traceable to over a thousand miles away from the farms of the upper Midwest, and all points further south. The origin, in other words, is farm run-off of nutrients from manure and chemical fertilizers. 

Farmers in these states have animals that produce manure. They also use fertilizers on their fields. With time and rainfall, nutrients from these sources seep into the Mississippi and any of its countless tributaries. Making their way eventually to the Gulf of Mexico, these nutrients in the manure and fertilizers combine with the heat of the Gulf to spawn catastrophically large algal blooms that kill everything in its wake.

Well-meaning farmers of the Dakotas, say, or Minnesota, or Wisconsin, may never know of the distant consequences of their actions. As such, it’s nearly impossible, and perhaps even unfair, to hold any one person responsible. How would you ever know, for instance, that this farmer’s fertilizer applications, as opposed to that farmer’s application, led in part to the dead zone that occurs so far downstream in space and time? In general, we can rightly say that farm manure and the application of chemical fertilizer and its subsequent nutrient-rich run-off cause of the dead zone in the Gulf, but for any one particular farmer it is much harder to make a causal attribution. 

The Gulf of Mexico dead zone, along with its distant causes, is a perfect analogy to the use of prescription opioids and the resultant opioid epidemic of addiction and overdose.