Presence of heavy metals in raw bovine milk from Machachi, Ecuador

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Francisco De la Cueva
Alexandra Naranjo
Byron Humberto Puga Torres
Eduardo Aragón


The evaluation of heavy metals in milk can be considered as an indicator of environmental contamination of a place, so the objective of the investigation was to determine the presence of Lead, Mercury and Arsenic in raw milk from Machachi, Pichincha Province-Ecuador. Fifty eight samples were collected from twenty nine dairy farms with extensive grazing system and located up to a maximum of one kilometer around the Municipality of Machachi, where there is industrial activity and is near the Panamericana Sur. The samples were analyzed using the atomic absorption spectrophotometry technique by a hydride generator (Mercury and Arsenic) and with a graphite furnace (Lead). All the samples analyzed showed Lead levels, with an average of 0.208 mg/kg (range between 0.0016 to 0.719 mg/kg), of which 98.28% (57/58) contain levels higher than the maximum allowed by the NTE INEN 9 of 0.02 mg/kg. Mercury was also detected in four samples (mean of 0.00009 mg/kg, range between 0.00 to 0.002 mg/kg) and Arsenic in two samples (mean of 0.00003 mg/kg, range 0.00 to 0.001 mg/kg), however, the They were below the limit allowed by the Codex Alimentarius (0.01 mg/kg) in food in general. With the results obtained, it is concluded that there could be an area contaminated with Pb, so continuous monitoring of milk should be carried out, and the investigation should be expanded to possible sources of contamination, such as drinking water, irrigation water, fodder and food received by dairy cows in the area.
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