The United States Coast Guard and Customs and Border Protection are monitoring vessel traffic and cargo departing the port in Tianjin, China, following the explosions earlier this months, over concerns that there may be hazardous ash, debris, or residues on vessels or cargo bound for U.S. ports.

“There have been no reports of vessels with confirmed hazardous debris or residues onboard,” said A Coast Guard notice. “However, U.S. companies are looking for reassurances regarding the health and safety of those who handle shipping containers across the supply chain. The federal government is working with local, state and federal port and international partners to coordinate efforts to identify any potential risks on inbound vessels and cargo to help ensure public safety.”

Vessels impacted by the Tianjin explosions are expected to call on U.S. ports over the next several weeks.

Based on the currently available, the Coast Guard is concerned that impacted vessels and cargo may have an increased risk of exposure to potentially hazardous chemicals. Several hazardous chemicals are reported to have been in the main warehouse, including sodium cyanide and calcium carbide.

“Given the substantial size of the explosions and the suspected hazardous chemicals that were involved,

ships and cargo in port at or near the times of the explosions may have been exposed to potentially

hazardous dust, ash, or debris,” said the Coast Guard notice.

The Coast Guard is primarily concerned about vessels that had cargo bays or hatch covers open when the blasts occurred, and any cargo or containers that were exposed during the explosions.

“The mere presence of vessel or cargo in Tianjin in the time window of concern does not necessarily mean that the impacted vessel must have been exposed and has a hazardous condition,” the Coast Guard added. “However, out of an abundance of caution, the Department of Homeland Security is monitoring all U.S. bound cargo and vessel traffic that were in the port of Tianjin on or after August 12.”

Regulations require the timely reporting of any potential hazardous conditions to the nearest Coast Guard Captain of the Port.