Dangers to Brain, Mind and Health

Dr. Katy Nelson, ND

Under normal breathing conditions, air and airborne particulates are adsorbed in lungs. Scent is different. Evaporated non-particulates like fragrance are absorbed through our nose into our brain where it is used physiologically to guide behavior and promote survival. Both the nose and the lungs have specialized physical and chemical defense mechanisms, including immune reactions such as sneezing, coughing, and tear and mucous production, which attempt to protect us from harmful airborne agents. But what happens to our health, our brains and especially our mind, when exposure taxes normal immune response? This is the second part in a series examining what we may be doing to ourselves, others and our environment when we use synthetic scents and “air fresheners.”

In Part 1 we learned that environmental information about taste, touch, temperature, sound, etc., gathered by every sense organ except the nose, is translated to the brain via the central nervous system traveling through the spine. Smells, odors, fragrances, smoke and other vapors, however, have a direct access to the brain. Traveling upward through the nose, scents pass through a skull opening called the “cribriform plate” where they are received by cells of the “olfactory bulb” (OB). Scent chemistry then transfers through the OB nerves ending in an area of the brain known as the limbic system.¹

A complex of interconnected nuclei, the limbic system governs emotions, mood, motivation, memory and learning. It governs pain and pleasure including the release of several hormones affecting our sexuality.¹ It has also been discovered to be involved in epileptic seizures.² Thus, what we inhale through our nose may influence us quite profoundly, affecting our physical brain and mental health. This power to influence, even manipulate, is certainly not lost on manufacturers and marketers. Consider the “new car smell”.

In Part 1 we also learned that manufacturers are not required by the FDA to reveal ingredients considered to be proprietary trade secrets. However, two of the identified ingredients in synthetic “air fresheners”, ethanol and formaldehyde, used to aerosolize other ingredients including synthetic fragrance, are known neurotoxins and suspected carcinogens. Because these compounds readily evaporate they are called Volatile Organic (carbon containing) Compounds, or “VOC”s.³ [VOC awareness has created a market for VOC-free paints.]

Many organisms, including mammals and fish, have a major detoxification pathway in the liver known as the Cytochrome P450 (CYP) pathway, a “superfamily” of enzymes that oxidatively modify or degrade hormones, fats, drugs and chemicals into safer metabolites.⁴ This pathway may be activated or inhibited by compounds, a fact doctors must consider when prescribing a “safe and effective” drug dose. VOCs and PAHs (Polyaromatic Hydrocarbons) activate (“induce”) the liver’s CYP pathway and are metabolized by it when intact.

Over thirty year ago, scientists discovered a link between the CYP, circadian rhythms (“biological clocks”) and the pineal gland, located just outside the limbic area of the brain.⁴ More recently, scientists have discovered the existence of the CYP system in the brain, although they point out that mammalian brain levels are “considerably lower than in the liver.”⁵

What happens when pollution levels increase? Although not mammals, a study of rainbow trout exposed to higher levels of PAHs revealed higher CYP levels⁵, demonstrating an amount of organism adaptability.

Another form of adaptation, “neurogenesis”, known to occur in the OB and the limbic areas governing new memory, learning and emotion, is demonstrated in new research published in 2015 using “post mortem brain samples from Douglas-Bell Canada Brain Bank”. New stem cells were discovered to migrate into place in the OB before they are mature,⁶ and therefore become “accustomed” or reset to new levels in their more toxic environment.

But, what happens when pollution levels or frequency taxes the CYP? In the above brain bank study, stem cell migration and maturation in the OB were discovered to be affected in samples from depressed and suicidal individuals.⁴ In the rainbow trout studies, “reproductive disturbances” were linked to PAH induction of the CYP in male brain cells associated with sperm development.⁵

Indirect reproductive disturbances were also found. Children of factory PAH environmental exposed workers have an increased risk of childhood brain tumors. “Fetal growth and neurodevelopment, including verbal IQ” have a threefold adverse risk associated with prenatal PAH exposure compared to only post natal exposure, with a protective effect noted by breastfeeding for at least six months.⁷

Far from being friendly helpers for social settings, synthetic fragrances in air fresheners, candles and even body products contribute to mood disorders, memory and learning impairments, epileptic seizure medication, and reproductive disorders including neurologic deficits among prenatally exposed populations. Do we really want them?

Economics in a free market society generally promotes a return of profit into generation of greater profit, through research, product development and lobbying. Thus, we must remember that when we buy products which are antithetical to our health and nature, we will reap a reward of corporate investment antithetical to our health and nature.

In part 3, we’ll examine other, safer alternatives.

Nelson_headshotKaty Nelson, ND, (Bastyr ’94), with an office since 1997 in Michigan’s rural Upper Peninsula on the shores of beautiful Lake Superior, promotes our Nature devoted profession through consultation, writing and mentoring. She is joined by Bastyr grad, former mentoree and Pediatric specialist, Alicia Smith Dambeck, LAc CH (also ad locum in St. Paul with Amy Johnson Grass, ND). Since 2011, Dr. Katy has been ad locum herself in SW FL for family matters.


  1. Vokshoor, A, Meyers, AD. Olfactory System Anatomy. : Overview, Olfactory Epithelium, Olfactory Nerve and the Cribriform Plate. 2013. Available at: http://emedicine.medscape.com/article/835585-overview. Accessed June 15, 2015.
  2. Nouri, S. Epilepsy and the Autonomic Nervous System. Benbadis SR, ed., eds. : Overview, Methodology, Ictal (Peri-ictal) Autonomic Changes. 2013. Available at: http://emedicine.medscape.com/article/1186872-overview. Accessed June 28, 2015.
  3. Volatile Organic Compounds (VOCs). Definition Page. 2014. Available at: http://toxics.usgs.gov/definitions/vocs.html. Accessed June 28, 2015.
  4. Froy, O. Cytochrome P450 and the biological clock in mammals. National Center for Biotechnology Information. 2009. Available at: http://www.ncbi.nlm.nih.gov/pubmed/19275546. Accessed June 28, 2015.
  5. Andersson, T, Goksøyr, A. Distribution and induction of cytochrome P450 1A1 in the rainbow trout brain. Fish Physiol Biochem Fish Physiology and Biochemistry. 1994;13(4):335–342. doi:10.1007/bf00003438.
  6. Mechawar, N. Study on neurogenesis in the olfactory bulb. ScienceDaily. 2015. Available at: http://www.sciencedaily.com/releases/2015/05/150521144040.htm. Accessed June 15, 2015.
  7. Jedrychowski, WA, Perera, FP, Camann, D, et al. Prenatal exposure to polycyclic aromatic hydrocarbons and cognitive dysfunction in children. Environ Sci Pollut Res Environmental Science and Pollution Research. 2014;22(5):3631–3639. doi:10.1007/s11356-014-3627-8.
Recommended Posts
Showing 1 comments
  • Lori

    I’m trying to find out more about Air Wick Pure. Having difficulty finding anything that doesn’t lead to their website. Thank you for this series! I stopped using all these toxic fragrances in my home 2+ years ago.

Leave a Comment