[1] WHO, Geneva, Switzerland
[2] Publ Hlth & Med Sociol, Geneva, Switzerland
[3] Cairo Univ, Dept Ind Med & Occupat Dis, Cairo, Egypt
[4] El Azhar Univ, Fac Med G, Dept Community & Ind Med, Cairo, Egypt
[5] El Azhar Univ, Fac Med G, Dept Community & Ind Med, Occupat Hlth, Cairo, Egypt