I’m afraid I don’t have much interesting to say about this link, but I just can’t scrape my jaw off the floor. There’s a story on Alternet about the incidence of autoimmune disorders, The Autoimmune Epidemic: Bodies Gone Haywire in a World out of Balance. I’m simply floored by some of the accounts, the numbers, and the whole phenomenon. I wish I had something to add, but I thought the least I could do was point out the story to some of our readers.
The autoimmune system is of special interest to those of us concerned about how environmental factors affect the development of organisms, including humans, because it is one of the clear cases of a system that gets substantial input from the environment to accomplish basic functions. We also find that it offers all sorts of interesting examples of non-genetic forms of heredity, including influences in utero and the widely-recognized importance of breast feeding for shaping the immune system. Less widely understood are the effects of changing environment on immune system functions in things like allergies.
Autoimmune disorders are at the more severe end of the spectrum, and I wouldn’t even hazard to guess at the influence of environment on their emergence. As the article points out, the rates of autoimmune disorders have grown significantly over recent decades: from the story on Alternet (all close paraphrases), the incidence of lupus has nearly tripled in the US in four decades and may have increased more rapidly among African-Americans; rates of multiple sclerosis have increased all over the industrialized world; the incidence of Type 1 diabetes, in which the immune system attacks insulin-producing cells in the pancreas, has increased fivefold, with stunning increases in very young children; and a host of other conditions, such as scleroderma, Crohn’s disease, autoimmune Addison’s disease, and polymyositis, all evidencing markedly increasing rates. The numbers presented in the story, especially the assertion that one in twelve Americans — one in nine American women — will contract some autoimmune disorder almost beggars the imagination.
Author of the book on which this story is based, Donna Jackson Nakazawa, says that according to most epidemiologists with whom she’s talked, the increasing rates may be due in part to better diagnosis, but that some of the numbers cannot be explained this way; they’re simply too great. The question then is what is causing this increase, and environmental causes — something in industrialized societies that convinces individuals’ immune systems to turn on their bodies — seems to be at fault. Nakazawa lays out some pretty damning circumstantial evidence for a whole range of chemicals, but the most salient fact, as far as I was considered, was the simple increase in the number of synthetic chemicals around us. As Nakazawa says in an interview, on average 1700 new chemicals are added to our environments each year. Potential culprits include pesticides, textile dyes, paints, solvents (such as TCE), benzene, asbestos, silica dust, asbestos, PCBs and vinyl chloride, among other things. Makes me more and more glad I moved to a farm and drink rainwater! Nakazawa suggests that it’s likely not any one chemical that leads to these outcomes. She talks about a ‘barrel effect’; combine a whole range of things — stress-related cortisol, heavy metals, food additives, environmental chemicals, even hormones linked to women’s reproductive cycles — and you may get autoimmune disorders if the body’s ‘barrel’ of agents fills to a critical level. As she says in an interview:
…once the immune system becomes overburdened it can begin to send misread signals, causing the immune system to make costly mistakes and attack the body itself. Unfortunately in modern life we’ve created a perfect storm of factors — a plethora of chemicals, heavy metals, processed food additives, viral hits and stressors — for today’s autoimmune epidemic to take hold. So much of what we encounter in twenty-first century life is causing our barrel to fill to the brim — and spill over. At that point, disease strikes.
What I find interesting — well, sobering as hell — is that the autoimmune system seems to be one area where the human body’s plasticity leads to great variation; that is, when we ask what parts of the body are plastic, we at neuroanthropology tend to point to the nervous system, the brain, the endocrine system, even muscles and the like. But here’s a case where it’s clear that the immune system is one of the more plastic in our bodies, with potentially detrimental effects in an environment where so many new reactants are introduced.