Incident cases were women employed for at least
one year in the electrical manufacturing plant during
the period of 1974 to 2005 and who were diagnosed
with breast cancer (International Classification Of
Diseases (ICD), IX rev.: 174) in the period of 2002
to 2009, resided in Lombardy and had no previous
diagnosis of breast cancer in the period 1999 to 2001,
as identified according to the Lombardy hospital
discharge records.