NEW YORK, Feb 24 (Reuters) - New Jersey's ports and the public have suffered since the nation deregulated truckers, a new study said on Tuesday, citing problems ranging from increased pollution to reduced loading efficiencies.

After the United States deregulated truckers in 1980, many large companies were replaced by small companies that hire independent contractors and pay them by the load, according to the Rutgers University study.

Nearly 75 percent of the 299 contractors surveyed own their trucks, have net earnings of $28,000 a year, and lack healthcare.

As a result, their diesel vehicles tend to be older -- 11 years -- are less safe and spew 10 times more particulate pollutants than modern vehicles, the survey said.

Lack of health insurance means they might have to turn to public clinics or emergency rooms, which drives up spending by the state and federal government.

"The public bears the brunt of these costs, as well as the costs of injuries caused by the use of unsafe rigs and chassis carrying freight containers," the study said.

With the U.S. economy in recession, export-driven states are focused on keeping this sector strong, while competition among ports is intensifying.

Recent statistics for the New York City area, California and Connecticut demonstrate sharp differences among ports and between exports and imports.

New Jersey's ports are the busiest on the Atlantic coast, the biggest in the New York City area. Imports handled by all of the New York City area ports fell 2 percent in the first 11 months of last year, while exports rose 12.8 percent, according to the Port Authority of New York and New Jersey.