Overview
Oliveira Filho and colleagues measured cadmium, lead, copper, iron and zinc by ICP-OES in 142 raw milk samples from cows on 14 farms in the Garanhuns microregion of Pernambuco, Brazil, and tested whether road proximity, effluents and milking method explained the levels. Lead exceeded the Brazilian limit of 0.05 mg/L in 29.6% of samples, while cadmium was below 0.02 mg/L in all. Farms within 3 km of a major road produced milk with markedly higher cadmium and lead. Arsenic and mercury were not measured.
Key numbers
- Lead: mean 0.043 ± 0.002 (SE) mg/L, median 0.040, range 0.013 to 0.098 mg/L (Table 1, p. 5).
- Cadmium: mean 0.007 mg/L, median 0.006, range 0.002 to 0.016 mg/L (Table 1, p. 5).
- 42 of 142 samples above 0.05 mg/L lead; 138 of 142 above 0.020 mg/L (Section 3.1, p. 5).
- Milk from farms near major roads had 94% more cadmium and 90% more lead than milk from distant farms (Section 3.2, p. 7).
Methods (brief)
Five milliliters of milk were microwave-digested in nitric acid and analyzed in duplicate by ICP-OES. Detection limits in the digest were 0.012 µg/L for cadmium and 0.036 µg/L for lead, and all samples were above them. Blanks were subtracted and recoveries were 90 to 110%; no certified reference material is named. A general linear model, PCA and cluster analysis tested farm factors.
Evidence Fitness
A reasonably large on-farm sample with dates and a stated QA program. Results are per liter of raw milk from individual cows, not retail milk, and fat level is not separated. This is a proxy for semi-skimmed-milk and does not link that page. Group values for the road and effluent comparisons are shown only in figures.