The Crazy Reason You're Depressed

It could be a chemical intolerance, not a bad day at work, that's giving you the blues.

By Emily Main


Your coworker's perfume, that lingering smell of someone's overpowering fabric softener, the secondhand smoke floating through a crowded concert hall—for most of us, those are just annoyances that could put a damper on a fun night out or make your workday temporarily unpleasant. But for others, they're seriously debilitating.

"We may have a mild irritation to something, but some people have tremendously adverse reactions to very low levels of chemicals, chemicals most of us can't even smell," says David Katerndahl, MD, professor of family and community medicine at the University of Texas Health Science Center at San Antonio. It's a condition called chemical intolerance, he says, and according to a new study he's just published in the Annals of Family Medicine, the number of people who suffer from it is higher than most medical professionals suspect.

More Than Just Annoying

A chemical intolerance is more than just being annoyed by your coworker's cologne or having an allergic skin reaction to your fragranced laundry detergent. The cause may be genetic, he says, or simply a result of constant low-level exposure over a lifetime that causes an intolerance to build up, which might explain why chemical intolerance is typically diagnosed after the age of 30. People with intolerances to a number of chemicals suffer from multiple chemical sensitivity, or MCS.

According to previous studies, 13 to 33 percent of the public claims to be "unusually" sensitive to chemicals, but just 2 to 13 percent can be classified as chemically intolerant. But according to Dr. Katerndahl's study, 20 percent of the 400 adults he surveyed qualified as chemically intolerant.

And that has huge implications for the health care system. Generally, he says, chemically intolerant adults make more visits to emergency rooms—an average of 23 more per year—than healthy adults. The chemically intolerant adults in his study were also more likely to suffer from allergies, and they were more likely to meet the criteria for major depressive disorder and alcohol abuse. Panic attacks, he adds, are some of the most severe side effects. "It's a sudden overwhelming sense of dread or fear. People often think they're having a heart attack, so they go to ER with no idea what's happening to them," he says. The alcohol abuse could even be a coping mechanism, and not necessarily a side effect of the intolerance. "People may turn to alcohol or drug abuse as a way to deal with the anxiety," he says. A few other conditions you're more likely to have if you're chemically intolerant: heart problems, bronchitis, asthma, pneumonia, sinusitis, hypothyroidism, autoimmune diseases, irritable bowel syndrome, and migraine.

Getting diagnosed with a chemical intolerance might not be easy, either. It's an area that hasn't seen much research since Gulf War syndrome, the first condition linked to multiple chemical sensitivities that physicians believe was caused by pesticide exposures during the Persian Gulf War, and many psychiatrists and specialists tend to disregard both chemical intolerance and multiple chemical sensitivities because they're difficult to define, he says. In many cases, people with chemical intolerance or multiple chemical sensitivity are told they suffer from chronic fatigue syndrome or fibromyalgia, another condition pegged to unexplained chronic pain. "But many primary care physicians are interested in it, because they see so many patients in primary care settings that have different complaints."

Avoiding Chemicals in a Toxic World

All this boils down to the fact that our increasingly chemically saturated world is taking a toll. According to the United Nations, the chemical industry is one of the largest sectors of the world economy, and the production of chemicals is increasing at a rate of 3 to 4 percent each year. In the U.S. alone, there are more than 80,000 industrial chemicals used to produce consumer products, furniture, building materials, and pharmaceuticals, along with thousands of other uses.