Zero tolerance: The Federal Meat Inspection Act in 1994 defined the presence of E. coli O157:H7 in hamburger as an adulterant. Recalls of E. coli O157:H7 contaminated meat and related illnesses continued to grow over the next decade. With near regularity, E. coli O157:H7 recalls and illnesses seemed to begin in the spring and peak in late summer and fall.