Perhaps the biggest point for the question of racism is that fact that the play was written by a white man for another white man to perform in blackface. At the time, blackface was a novelty in performance (for another example, see Ben Jonson' THE MASQUE OF BLACKNESS). Aside from these general considerations, there are moments in the play that speak directly to racism:
1. In the first scene of the play, Iago tells Brabantio (Desdemona's father) " Even now, now, very now, an old black ram is tupping your white ewe." The quote references Othello's race and associates with a kind of predatory sexuality. This is echoed later in the play when Iago admits he is afraid of Amelia being similarly seduced by the Moor. Iago later compares Othello to a "barbary horse," another animal image used as a comparison for Othello.
2. In the same scene, Roderigo refers to Othello as the "thick-lips."
3. When Emilia discovers Othello after he has murdered Desdemona, she calls him a "blacker devil." This points to the larger issue of associating Othello's race with his jealous, irrationality and rage. This connects to Othello's much-debated trance in Act 4, Scene 1 which could be attributed to his being overcome by his jealous emotions.
The other side of the argument is that Othello is clearly beloved by most of the characters in the play and it is only Iago's machinations that undo him.
1. Desdemona defends her decision to marry him in Act 1 by stating "That I did love the Moor to live with him, My donwright violence, and storm of fortunes, may trumpet to the world."
2. When Cassio fears that Othello may have died at the beginning of Act II, he laments, "O, let the heavens Give him [Othello] defense against the elements."
The general picture painted by the men who surround Othello is that he is highly respected. This respect shared by the majority of the characters could be used to mitigate any concerns about race in the play. Also, since he iis subjected to evil manipulation, he is made more accessible to the audience.