The aim of this work was to determine the content of lead (Pb), chromium (Cr), cadmium (Cd), arsenic (As), copper (Cu), strontium (Sr) and thallio (Tl) in blood, milk and urine from cows fed forage irrigated with sewage water and cultivated in the vicinity of the Popocat epetl volcano and determine the rate of transfer of these elements from blood to milk and urine. Digestion was performed in a microwave oven (CEM-MarsX). The determination was made using an ICP -OES. The Cd in the blood was significantly higher than in milk and urine. The Cr in the blood was higher than in the urine. In milk the content of Pb and Cu was significantly higher than in blood. Sr and Tl concentration in the urine was higher than that detected in milk and blood and Pb in blood. Milk transfer Index revealed a significant difference in relation to the TI values found in the urine and only in the case of Cu in milk was TI > 1. In urine, the values found of Sr and Tl were higher than milk TI. It is concluded that when metals are ingested by cows in fodder, they are easily transferred to milk and urine through the blood. Presence of heavy metals in the different matrices determines the degree of environmental and trofic chain contamination with which we can consider the cow a biomarker.