Overview
Fuentes-Gandara and colleagues sampled raw milk from bulk tanks on 25 farms in Atlantico, Colombia, in the 2018 to 2019 dry season and the 2019 rainy season, and measured lead, chromium, arsenic and mercury. Year-round medians were lead 2.23, arsenic 2.93 and mercury 0.18 ug/L, with chromium much higher (median 44 ug/L). Lead, chromium and arsenic rose in the rainy season, and the zone around metropolitan Barranquilla had the highest levels.
Key numbers
- All samples: lead mean 3.19, median 2.23 ug/L (25th to 75th percentile 0.25 to 5.03) (Table 1, p. 1047).
- All samples: arsenic mean 2.46, median 2.93 ug/L; mercury mean 0.35, median 0.18 ug/L (Table 1).
- Lead mean 9.71 ug/L in the rainy season versus 1.10 ug/L in the dry season (Results, p. 1047).
Methods (brief)
Microwave digestion of 5 mL milk in nitric and hydrochloric acid; lead and chromium by graphite furnace AAS, arsenic by hydride generation AFS, mercury by direct mercury analysis. Detection limits 0.5 ug/L lead, 0.8 arsenic, 0.1 mercury, 0.2 chromium; spike recoveries 88 to 94 percent. Results per litre, kept unconverted.
Evidence Fitness
Good design (two seasons, 25 farms, sensitive methods) but several text statements conflict with Table 1, including a claim that lead exceeded the EU 20 ug/L limit when all reported statistics are below 10 ug/L. Cadmium was not measured. For semi-skimmed-milk this is a proxy: raw farm milk, fat level not separated and not retail, so that page is not linked.