When it comes to the chemical free-for-all that generally characterizes industrial agriculture’s approach to modern farming, there’s no doubt that the public has become increasingly wary of pesticides. But what about all that fertilizer?

Somehow, the chemicals used to feed crops don’t seem to have aroused quite the same level of suspicion as those used to kill weeds and pests. Most of us are at least vaguely aware that fertilizer-laden runoff—not to mention waste seeping from huge factory farms—has been blamed for today’s toxic algae blooms and the 6,000-square-mile “dead zone” in the Gulf of Mexico, which sounds like a sci-fi ecological horror film that happens to be true.

But a report released this week from the heartland—which is to say, the heart of industrial farming—suggests that we might do well to start worrying about what the deluge of fertilizers is doing to our bodies too.

Just as it has taken years for the public to begin to accept that carbon dioxide, of all things—the stuff we exhale—could possibly be a pollutant and responsible for global warming, the same might be said for the nitrogen found in fertilizers. After all, nitrogen comprises nearly 80 percent of our atmosphere. How bad could it be?

Well, in addition to those toxic algae blooms, the folks at the Iowa Environmental Council found in a review of prior research that consumption of drinking water containing higher levels of nitrates—nitrogen-based compounds often associated with fertilizer runoff—has been linked to a number of human health effects. Those include birth defects related to brain and spinal development as well as bladder and thyroid cancers.