The American Chemical Society maintains the most comprehensive database of commercial chemicals in the United States. Fifteen thousand new chemicals are registered to the database not every year, not every month, not every week, but every day: 15,000 per day. We’re exposed to these chemicals directly through the products that use them (such as personal care products) as well as incidental exposure (such as agricultural drift containing pesticides and herbicides).
For decades, scientists have become concerned about how these chemicals find their way into water, soil, and air by pathways such as wastewater systems—for example, when people urinate out pharmaceuticals or dump drugs down the sink or toilet. The concentration of such chemicals in the environment is extremely low compared to direct exposures by factors of hundreds of thousands or even hundreds of millions. After release into the environment, some chemicals find their way into plants and animals—and us.
Because of advances in monitoring technology, it’s possible to detect these background exposures in concentrations never before possible. According to environmental health scientist Deborah Swackhamer of the University of Minnesota, “We don’t know what these background levels mean in terms of environmental or public health.”
Remember that “we don’t know” means we don’t know. It does not mean it’s safe to be exposed. So once again, we are the subjects of an uncontrolled, involuntary medical experiment.
A few years ago, I reported on the effect of Prozac® in ultra-minute amounts. Researchers found that background levels of that famous serotonin reuptake inhibitor killed off Great Lakes bacteria (Kaufman, 2011). What does that mean for our own gut bacteria—from either a dose of the drug or from a chronic exposure to background levels in our drinking water?
We already know that our gut bacteria have a crucial role in our physical and mental health, working not only on digestion and nutrition but on immunity and mood—our gut produces something like 40% of the neurotransmitter serotonin, the levels of which Prozac® inhibits by block serotonin’s reabsorption. A recent literature review in the journal BioEssays discusses how gut microbes affect the eating behavior of their hosts (that’s you and me) in order to get the food they need.
This is a novel perspective because it’s not just about what physiological functions gut bacteria perform. It’s about those functions from the bacteria’s perspective. It is, actually, an ecological perspective—not as a metaphor so that you’ll treat you microbiome with care but as an actual description of how you live with other creatures essential to your health—and theirs.
The mechanism is this: if you eat something a microbe species doesn’t like, it produces biochemicals that have negative mood and taste effects; if you eat something a microbe species likes, it does the opposite (biochemicals that have positive mood and taste effects).
From an ecological perspective, this is a classic strategy for the evolution and stability of an ecosystem: everyone gets what they want to eat, with some tolerance or resistance from other members of the community. Another feature of the relationship between eating behavior and gut microbes is that microbe diversity and composition are closely associated with host diet, nutrition, and energy metabolism—for example, body weight and composition.
To connect this to the Prozac® thread, note that the phenomenon of obesogens (chemicals associated with weight gain) was first observed in people taking antidepressants, in particular serotonin reuptake inhibitors such as Prozac®.
So here’s the question: what effect does exposure to those 15,000 chemicals per day have on our microbiome? And what effect does that have on our health generally, not just our eating habits?
We don’t know.
And those who are asking tend to ask fairly narrow questions, although they seem huge. I’ve already mentioned the effect of background Prozac® concentrations on Great Lakes bacteria. The decrepit Toxic Substances Control Act has researchers performing outmoded risk assessments on individual chemicals—I haven’t mentioned the little bit we know about what happens when someone is exposed to multiple chemicals or what happens when a chemical released into the environment transforms into some other chemical that might be more dangerous or less dangerous (we don’t know) or what happens from exposures to background electromagnetic radiation (ionizing, for example from nuclear power plants, and non-ionizing, for example from smart phones) or combined exposures to radiation and chemicals.
We don’t know.
But I digress. You could conclude that you’re swimming in a toxic soup. That’s not the point I want to make. I want to draw your attention to the fact that, from an environmental health and public health and your body’s health standpoint, those 15,000 chemicals per day need to be seen as an ecological problem.
What I mean is that it is grossly inadequate to perform a risk assessment that tells us what concentration of one of those 15,000 chemicals will kill half the population of lab animals—that’s a basic benchmark in risk assessment. That tells us nothing. What it does is allow regulators to permit a chemical’s use and for us to be mollified with fairy tales about its safety.
We still don’t know what the effect is on life—the society of organisms that live their lives together, its members variously tolerating, resisting, avoiding, and supporting each other, evolving and sustaining itself through time.