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Concentrations of Cadmium, Lead and Mercury in Raw Bovine, Ovine, Caprine, Buffalo and Camel Milk

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Overview

Parsaei and colleagues measured cadmium, lead, and mercury in 1100 raw milk samples from multiple animal species. The study is routeable for milk and dairy occurrence evidence because it reports ppb concentrations by species, age, and season. It found the highest concentrations in raw bovine milk and seasonal elevation in spring.

Key numbers

  • Sample frame: 1100 raw milk samples collected from dairy farms in Isfahan Province, Iran between January 2017 and January 2018, comprising bovine (n=300), ovine (n=250), caprine (n=250), buffalo (n=150), and camel (n=150) milk from 2-5-year-old animals.
  • Overall mean concentrations: Cd 3.62 +/- 0.35 ppb, Pb 11.73 +/- 1.09 ppb, and Hg 4.35 +/- 0.42 ppb.
  • Overall ranges: Cd 0.06-14.03 ppb, Pb 0.12-33.62 ppb, and Hg 1.03-10.38 ppb.
  • Raw bovine milk had the highest reported means: Cd 4.05 +/- 0.38 ppb, Pb 12.36 +/- 1.21 ppb, and Hg 5.76 +/- 0.53 ppb. Raw camel milk had the lowest: Cd 1.22 +/- 0.11 ppb, Pb 3.14 +/- 0.26 ppb, and Hg 2.36 +/- 0.21 ppb.
  • Animals at least five years old showed roughly two-fold elevations over the overall species means. Bovine 5≤ animals: Cd 10.33 +/- 1.26 ppb, Pb 23.72 +/- 2.29 ppb, Hg 7.14 +/- 0.68 ppb. Buffalo 5≤ animals: Cd 12.02 +/- 1.04 ppb, Pb 28.61 +/- 1.02 ppb, Hg 8.24 +/- 0.65 ppb (Table 2).
  • Spring samples were the highest across all species. Buffalo spring: Cd 12.00 +/- 1.01, Pb 25.59 +/- 2.12, Hg 8.11 +/- 0.60 ppb (Table 3).
  • The authors report that overall mean Cd and Hg concentrations were below the standard allowed limits they tabulated, while overall mean Pb concentrations exceeded those limits.

Methods (brief)

Mercury was determined by cold vapor atomic absorption spectrophotometry using a FIAS 4100 flow injection mercury/hydride analyzer (Perkin Elmer, Foster City, CA, USA) at 253.7 nm. Cadmium and lead were determined by graphite furnace atomic absorption spectrophotometry on a Perkin Elmer 4100 with pyrolytic platform graphite tubes (AS-40), using ascorbic acid and palladium for matrix modification. Accuracy was verified against reference material BCR No 150. Mean recoveries were 88% for Hg, 93% for Cd, and 96% for Pb. Reported detection limits (3xSD) were 0.11, 0.041, and 0.039 mg/L for Hg, Cd, and Pb respectively; see Verification notes regarding the apparent unit inconsistency between these LOD values and the reported sample minima.

Implications

Certification: Supports raw milk and dairy context, especially seasonal and species variance.

Courses: Useful for teaching seasonal variance and animal-species differences in dairy metals.

App: Can inform dairy ingredient priors with geography and raw-milk caveats.

Update history

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