The proposed fines cover two shipments of materials in May and June 2014, and come less than two weeks after the FAA proposed a $350,000 fine against Amazon for a shipment that injured several UPS workers who handled a package.

Amazon has 30 days to respond to the FAA.

The FAA said Amazon in May 2014 sent packages containing corrosive rust stain preventer from Illinois to Florida. Workers at FedEx’s sorting facility in Lake Wales, Fla., discovered one of the containers leaked through the cardboard box. The FAA proposed a $78,000 fine.

The FAA also proposed a $52,000 fine after it said Amazon sent a flammable gas from Whitestown, IN., to Glendale, Calif., in June 2014. Workers in UPS’s Louisville, KY. sorting facility discovered the container. The shipments were not properly marked as hazardous materials, FAA said.

Earlier this month, the FAA alleged that on Oct. 15, 2014, Amazon sent a UPS package with a one-gallon container of a corrosive drain cleaner for transportation by air from Kentucky, to Colorado.

The package leaked and nine UPS employees who came into contact with the box reported feeling a burning sensation and were treated with a chemical wash, the FAA said, in proposing a $350,000 fine.

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That’s the largest fine the FAA has proposed imposing on Amazon.

Amazon said in a written statement earlier this month that it ships “tens of millions of products every day and (has) developed sophisticated technologies to detect potential shipping hazards and use any defects as an opportunity for continuous improvement.”

Earlier this month, the FAA said that from February 2013 to September 2015, the government found Amazon had violated the hazardous materials regulations 24 other times and is seeking a total of nearly $1.3 million in fines. In at least 15 instances, hazardous material leaked.