Coal-Tar Sealants

Concerns for the environment and public health, as well as Maine law prohibiting sale and application

Maine Law | Frequently Asked Questions | Additional Resources | DEP Contacts

Many parking lots and driveways are coated with sealcoat, a dark, viscous liquid, to maintain and improve the appearance of the underlying pavement. Coal-tar sealants contain high levels of polycyclic aromatic hydrocarbon compounds (PAHs), which are known and probable carcinogens. Stormwater runoff from areas treated with coal-tar sealants can carry PAHs into streams, lakes, and marine waters, putting fish, other aquatic life and human health at risk.

Coal-tar sealcoat impacts
Coal-tar-based sealcoat is a potent source of PAHs and related chemicals. Worn particles of coal-tar-based sealcoat are transported by rain, wind, tires, and even our feet from pavement to other environmental settings. Sealcoat product (A), after it dries, gradually abrades to a powder and becomes part of the dust on the pavement (B). Pavement dust is transported by rainfall runoff (C) to stormwater-management devices (D) or to receiving streams and lakes (E). Pavement dust also adheres to tires (F) that track it onto unsealed pavement, and wind and runoff transport the dust to nearby soils (G). Sealcoat particles tracked into residences can become incorporated into the house dust (H). Graphic from USGS Fact Sheet 2016-3017.

Maine Law

In 2019, the Maine legislature enacted P.L. 2019, Ch. 493, An Act Concerning Pavement Sealing Products, which prohibits the sale and application of coal-tar sealant products on driveways and parking lots. Beginning in October 2023, wholesale and retail sales of coal-tar sealant products are prohibited, and application of coal-tar sealant products is prohibited beginning in October 2024.

The Department is responsible for ensuring compliance with the law. In 2022 and 2023, DEP provided information to retail stores and wholesale suppliers to raise awareness about the law and provide an opportunity to obtain alternatives by the time the ban comes into effect.

Frequently Asked Questions

Why are PAHs an environmental and health concern?

Coal-tar-based sealcoat products contain about 1,000 times more PAHs than asphalt-based sealcoat. PAHs are a concern because many cause cancer, mutations, birth defects or death in fish and other aquatic life. EPA has classified several PAHs as probable human carcinogens. Exposure to PAHs, especially early in childhood, has been linked to an increased risk of lung, skin, bladder, and respiratory cancers.

How can I tell if a product contains coal-tar?

Check the product’s MSDS (material data safety sheet) and look at its CAS (Chemical Abstracts Service) number. The CAS number for coal-tar is 65996-93-2. Choose products without this CAS. Some products may have a “coal-tar free” label.

What can I use instead of coal-tar sealants?

Petroleum asphalt-based sealants (CAS number 8052-42-4) are a readily available alternative to coal-tar-based sealants. Asphalt-based sealants have significantly lower concentrations of PAHs and lower potential for contributing harmful material into the environment. Asphalt-based sealants have been used in the western United States for decades.

Pavement options such as pervious concrete, permeable asphalt and paver systems do not require any sealants. These types of pavements also allow stormwater to naturally infiltrate, resulting in decreased runoff.

Web Sources and Additional Resources

DEP Contacts

General Questions
Wendy Garland (207) 615-2451,

Compliance/Enforcement Questions
Pam Parker (207) 485-3038,