Civil rights campaigner Rev Al Sharpton has called for a ban on racist and derogatory terms in rap lyrics at a series of rallies held across the US.
Rev Al Sharpton attended the protest rally in Detroit
Sharpton believes the entertainment industry should be pressured to clean up musicians' lyrics under the threat of the withdrawal of public money.
The Day of Outrage rally included protests in New York, Los Angeles, Detroit, Houston and Chicago.
Some people in the music industry have defended rappers' free-speech rights.
Public money, in the form of pension funds, is frequently invested in big business corporations such as entertainment companies Time Warner, Viacom and Vivendi.
"The opposition has tried to use the argument of free speech, but they don't have the freedom to use peoples' pension funds against their own will and interest," Rev Sharpton told Reuters.
But Clark McKinley, a spokesman for the Californian Public Employees Retirement System - the biggest US pension fund - said their job was to maximise returns, not make moral judgements.
DJ Don Imus was fired for using racist remarks on air
Rev Sharpton was among those who demanded that US radio DJ Don Imus be fired for referring to black female basketball players as "nappy-headed hos" in April this year. Imus was later sacked by CBS.
The campaigner staged an earlier rally in New York in May, picketing the major music labels and calling for an industry curb on sexist and racist insults.
Industry players claim the derogatory terms at the centre of the debate should be blanked out of radio versions of their songs.
"We take issues regarding the role of women and minorities in society very seriously," said a statement from Warner Music Group in May.
"We edit explicit lyrics, including those that are the focus of the current public debate, from content."