What you need to know about coal tar sealants

Sealants are widely used liquids that are applied to driveways and parking lots to protect and improve the appearance of paved surfaces. Coal tar-based sealants are the most commonly used sealant type in the Midwest. Coal tar sealants have been the subject of recent scrutiny for the risk they pose to human health, water quality, and aquatic life. Coal tar is a byproduct of coal. Coal tar is composed of Polycyclic Aromatic Hydrocarbons (PAHs), which represent a class of chemicals known to cause cancer, genetic mutations, and birth defects. Coal tar sealants contain nearly 1,000 times higher PAH concentrations than asphalt-based sealants.

Where are PAHs from coal tar sealants found?

  • PAHs are released into the air during and after application of coal tar sealants; wind can disperse them
  • Tire abrasion and street sweeping dislodges PAHs from surfaces coated in coal tar and results in pavement dust
  • Pavement dust is transported by runoff to stormwater systems and waterbodies where it sticks to sediments
  • Pavement dust is blown into nearby soil resulting in soil contamination
  • Walking on surfaces sealed with coal tar introduces PAHs into homes where it settles as household dust

PAHs in the Grand Traverse Bay watershed

In 2018, the State of Michigan conducted sediment testing in Traverse City area waterways. These results show that PAH levels are elevated in sediments in both Kids Creek and the Boardman River. Results also indicate that these concerning PAH levels are likely due to the wide-spread local use of coal tar sealants.

How can I be exposed?

  • Inhaled during activities on or near a surface coated with coal tar sealants
  • Walking on surfaces coated in coal tar sealants can introduce PAHs into the home
  • Skin contact either directly or by touching toys or other objects that have been in contact with pavement sealed with coal tar

What are the health effects of PAHs from coal tar sealants?

  • Humans
    • Birth defects
    • Increased cancer risk
    • Genetic mutations
  • Aquatic species such as fish and invertebrates:
    • Stunted growth
    • Reduced reproduction
    • Immune system impairment
    • Increased cancer risk
    • Premature death

Who regulates coal tar sealants?

Townships and municipalities have recently enacted bans on the sale and use of these products, including Traverse City (2020) and the Village of Elk Rapids (2018). Some states have issued state-wide bans on coal tar sealants and other sealants that contain high concentrations of PAHs. Coal tar sealants are not regulated by the federal government or the State of Michigan.

What can I do to protect myself and my family from PAHs in coal tar sealants?

  • Consider eliminating seal coating as a maintenance practice for paved surfaces
  • Seek alternative sealant products with lower levels of PAHs
  • Remove shoes before entering homes to avoid tracking in pavement dust
  • Encourage local officials to stop using coal tar and other high PAH sealants on public paved surfaces
  • Advocate for a local coal tar and high PAH containing sealant ban in your community
  • Educate others about the human health and environmental risks of using coal tar sealants (printable brochure)