A fury erupted Tuesday over Mayor Michael Bloomberg's remarks that a police detective who worked on the World Trade Center cleanup is "not a hero" because his death was ruled unrelated to the toxic debris.

The family of retired police detective James Zadroga and the city's police unions called for an apology from the mayor, saying his comment was heartless. They said every member of the police force is a hero for putting their lives on the line, particularly those who worked in the months-long cleanup at ground zero after the Sept. 11, 2001, terrorist attacks.

Zadroga put in more than 400 hours at ground zero, and his death at 34 made him a symbol of ailing Sept. 11 workers around the country. A New Jersey medical examiner ruled last year that Zadroga died from inhaling the toxic ground zero dust.

Speaking Monday to students at Harvard University, where he was accepting a public health award, Bloomberg was asked about the idea of applying hard science to public policy. In his answer, he brought up Chief Medical Examiner Charles Hirsch's recent conclusion that Zadroga's fatal lung disease was not from trade center dust but was from ground-up pills he had been injecting.

Zadroga's family disputes Hirsch's findings about drug use. The family has released more than 100 pages of medical records that showed Zadroga developed breathing problems just after the 2001 attacks.

The family had sought Hirsch's opinion as part of the city's required process to include additional names on the official Sept. 11 victims list and memorial wall to be built at ground zero.

"The mayor is a political person, he's acting on a political agenda — to me, he's heartless, he has no compassion whatsoever for people and their lives and their families," said the detective's father, Joseph Zadroga.

Detectives' Endowment Association President Michael Palladino said the police force had lost faith in the mayor and City Hall, and that Bloomberg's comments stung the hundreds of rescue workers who say they have become sickened after working on the cleanup.

"Hirsch's findings and the mayor's comments are an insult to the families of those first responders who made the ultimate sacrifice, like Jimmy Zadroga, and all those other first responders that are still suffering with the illness of 9/11," Palladino said.

At a news conference in Brooklyn, Bloomberg backpedaled carefully, praising the detective for his "impressive record."

"I did not mean to hurt the family or impugn his reputation," Bloomberg said.

It is not the first time that Bloomberg — who took office less than four months after the Sept. 11 attacks — has been accused of being insensitive to Sept. 11-related matters. In his first year as mayor, he angered victims' relatives when he said he favored a "less is more" approach to the memorial. He further offended them when he said downtown residents would not want to live next to a "cemetery."