The U.S. Coast Guard announced in a bulletin earlier this week that it as well as officials from the Department of Homeland Security agencies are monitoring vessels and cargo headed to the country that were in the Tianjin, China port during either or both of the explosions that left hundreds dead or injured.

“Vessels impacted by the Tianjin explosions are expected to call on U.S. ports over the next several weeks,” the Coast Guard said in its bulletin to maritime industry officials. “There have been no reports of vessels with confirmed hazardous debris or residues onboard, however U.S. companies are looking for reassurances regarding the health and safety of those who handle shipping containers across the supply chain.”

Nearly 150 people were killed in the blasts that happened at the port on Aug. 12 and Aug. 15, with another 27 listed as missing, according to the Chinese state-run news agency Xinhua.

While the blast has made international headlines, Coast Guard officials are concerned about the lack of information known about what contaminants to which ships, cargo and crew members may have been exposed. They urged vessel owners and operators to inspect for ash or other debris from the blasts that landed on the ship or cargo containers.

“There is not yet available a comprehensive list of chemicals that were involved in the Tianjin incident; however, several hazardous chemicals are reported to have been in the main warehouse, including sodium cyanide (UN1689) and calcium carbide (UN1402),” the bulletin stated.

Of particular concern to federal officials are any vessels that were in the port on either or both days and had cargo bays or other hatches open during the blasts and subsequent fallout. Any suspected hazardous conditions, illnesses or unknown substances discovered on board should be reported to Coast Guard officers immediately, according to the bulletin.

The Coast Guard has the power to prohibit a ship from entering an American port or direct it to a location where it can be evaluated safely for any potential threats.

“Representatives of impacted vessels should be prepared to demonstrate to the cognizant (Coast Guard) and (U.S. Customs and Border Protection) authorities the actions that they have taken to ensure that no hazardous conditions exist onboard their vessels or with the cargo as a result of the explosions in Tianjin,” the Coast Guard said. “Federal government experts are currently developing guidelines for sampling testing to facilitate those efforts.”

Those guidelines will be delivered to the Coast Guard’s captain of the port at each port location as soon as possible, according to the bulletin.

As U.S. officials released the bulletin, China announced through Xinhua it has arrested a dozen officials authorities said were suspects in the blasts. According to Chinese police, those arrested were suspected of illegally storing dangerous chemicals and other toxic materials at the port. In addition, 11 port executives and government leaders were being investigated for their roles as well.

First responders represented a significant amount of the casualties. According to Xinhua, 89 firefighters and nine police officers are among the dead, and 15 firefighters and two law enforcement officers are among the missing.