29 CFR §1606.8

1. (a)The Commission has consistently held that harassment on the basis of national origin is a violation of title VII. An employer has an affirmative duty to maintain a working environment free of harassment on the basis of national origin. 8
2. (b)Ethnic slurs and other verbal or physical conduct relating to an individual's national origin constitute harassment when this conduct:
   1. (1)Has the purpose or effect of creating an intimidating, hostile or offensive working environment;
   2. (2)Has the purpose or effect of unreasonably interfering with an individual's work performance; or
   3. (3)Otherwise adversely affects an individual's employment opportunities.
3. (c)[Reserved]
4. (d)With respect to conduct between fellow employees, an employer is responsible for acts of harassment in the workplace on the basis of national origin, where the employer, its agents or supervisory employees, knows or should have known of the conduct, unless the employer can show that it took immediate and appropriate corrective action.
5. (e)An employer may also be responsible for the acts of non-employees with respect to harassment of employees in the workplace on the basis of national origin, where the employer, its agents or supervisory employees, knows or should have known of the conduct and fails to take immediate and appropriate corrective action. In reviewing these cases, the Commission will consider the extent of the employer's control and any other legal responsibility which the employer may have with respect to the conduct of such non-employees.