Disclaimer: Articles referenced are from 2016-17. Some ingredients/stats about dryer sheets may have changed very significantly since then so this article was written to give a general idea about their health hazards.
As of 2017, the United States Consumer Product Safety Commission didn't require ingredient lists on dryer sheets.
"Seven hazardous air pollutants and 25 volatile organic compounds (VOCs)" were found in the laundry vent emissions of a particular experiment of "scented fabric softening and dryer sheets" used in clean washers and dryers. Included were chemicals present in automotive tail pipe exhaust; benzene and acetaldehyde have no safe level(1).
Fourty-four percent of tested scented laundry products gave off one or more cancer-causing air pollutants(1).
A 2016 study found that 12.5% of folks believed scented laundry products were causing them health problems. These included "respiratory issues, runny noses, asthma attacks, skin issues, migraines and even gastrointestinal symptoms."(1)
Some more rapidly-noticed effects of laundry-product scents are "migraines, asthma attacks, eye and throat irritation and contact dermatitis." Some dryer sheets are especially polluted and may have quaternary ammonium compounds, infamous for bringing on asthma. Other chemicals endanger wild animals(1). Important to remember: skin is "the most absorbent organ in your body."(2)
"Benzyl alcohol- Causes irritation within the upper respiratory tract... nausea, vomiting... and dramatic drops in blood pressure."(2)
"Acetaldehyde... in fake fragrance blends... adversely impacts the kidneys, nervous and respiratory systems."(1)
In the 1990s, an EPA/industry-generated list made of common ingredients in fabric softeners included multiple ingredients implicated in neurological disorders. Brain damage could come from - choloform(2).
Simply line-drying clothes outside saves energy and avoids toxic laundry scent chemicals(2).
My mom uses wool dryer balls in our clothes dryer - a much healthier option!
References:
1. Zerbe, Leah. "Stop Using Dryer Sheets Immediately!" Dr. Axe: Co-Founder of ANCIENT NUTRITION. Dr. Axe. June 14, 2017. Web. November 4, 2023. https://draxe.com/health/dryer-sheets/.
2. DailyHealthPost Editorial. "Dryer Sheets Cause Hormone Imbalance, Neurotoxicity, Respiratory Problems, and Even Cancer." Daily Health Post. Daily Health Post. April 23, 2016. Web. November 4, 2023. https://dailyhealthpost.com/dryer-sheets-dangers/.