AOHC: How Does Chemical Exposure Impact the Sense of Smell?

The nose knows. "The olfactory system is the oldest and most complex sensory system capable of conveying environmental information across long distances," according to Pamela Dalton, Ph.D., of Monell Chemical Senses Center at the University of Pennsylvania.

And, as Dalton told attendees at the American Occupational Health Conference (AOHC) in Atlanta yesterday, "In the workplace, the olfactory system is one of the most important warning systems."

Our sense of smell warns us away from a number of potentially harmful chemicals and substances, she said, partially because of the "miasma theory of disease. Bad smells equal sickness."

Our sense of smell impacts us in several ways, she noted:

  • Safety Warning signal for toxic gases, spoiled food, social blunders.
  • Quality of life Enhances enjoyment of food and beverages, intimate relationships.
  • Clinical significance Olfactory loss is an early signal of Alzheimer's Disease and other neuro-degenerative diseases.

However, warned Dalton, "Self-assessment of olfactory acuity is not reliable, particularly when loss is gradual."

Occupational chemical exposure can have an adverse effect on the olfactory system, said Dalton. Olfactoxins, substances that selectively target olfactory systems, can cause irreversible damage to the olfactory system. Then there are psychotoxins, substances that cause workers to manifest symptoms when smelling something perceived to be toxic.

Dalton suggested checking worker olfactory systems in one indication of chemical exposure. She noted workers exposed to one chemical, ammonia, for example, are often more sensitized to it and can identify it at very low levels, levels lower than workers who were never exposed to it.

Another indication of chemical exposure is a condition called dysosmia, which is distortion in the perception of odor quality. Olfactory receptors regenerate, said Dalton, often in four to six weeks after exposure. However, following dysfunction due to chemical exposure, the regeneration process gets disrupted.

"It's like a switchboard operator plugging you into a wrong number," said Dalton. For example, coffee might taste like lemonade, or a hamburger might taste like broccoli.

Age, disease and exposure history can impact a worker's sensitivity to odors, and risk perception and personality traits can influence the way a worker processes odor information. Dalton said the following perceptions of odors can trigger adverse effects through cognitive mechanisms:

  • Beliefs about odor source and consequences of exposure.
  • Adverse reactions of coworkers.
  • Stress or anxiety from other sources that might make workers more aware of smells is workplace.
  • Personality factors.

"In summary," said Dalton, "olfactory perception is a significant source of environmental information. Adverse responses to odorous chemicals can be mediated by beliefs and expectations, personality or stress, and psychosocial influences, such as reactions of coworkers.

"Perceptions of risk/toxicity signaled by odor may underlie many episodes of chemical intolerance or adverse symptoms from chemical exposure," Dalton concluded.

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