I''m a white male working in a predominant minority staffed and managed company. Several managers have accused me of racism.

As more minorities and women become business owners and managers, we have seen an increase in cases in which nonminority males have experienced discrimination and what lawyers call "hostile work environment."  The law prohibits discrimination or harassment based on race, and it applies equally to minority and nonminority workers.  Just as it is unlawful for a white business owner or supervisor to discriminate against or harass an African American worker, it is unlawful for a minority owner/supervisor to discriminate against or harass a white employee.  Though you really don't provide enough facts for me to give you much guidance, repeated allegations that a white employee is a "racist" made by an African American owner or supervisor may create a "racially hostile work environment" which violates the law.  I suggest you contact your local human rights or civil rights commission for guidance.