Health Risk Assessment of Heavy Metals in Local and Imported Milk Consumed in Nnewi, Nigeria

Abstract

This study assessed the potential health risks associated with cadmium (Cd), mercury (Hg), lead (Pb), zinc (Zn), iron (Fe), copper (Cu), and arsenic (As) in locally produced and imported milk consumed in Nnewi, Anambra State, Nigeria. A total of 24 milk samples were collected and categorized into four groups: locally produced liquid milk, imported liquid milk, locally produced powdered milk, and imported powdered milk. Heavy metal concentrations were determined using atomic absorption spectrometry.

The results showed that locally produced liquid milk contained the highest concentrations of Cd, Zn, Fe, Pb, and Cu, while imported powdered milk exhibited the highest levels of arsenic and mercury. Significant differences (p < 0.05) were observed in copper concentrations between foreign and local powdered milk samples, as well as in cadmium, zinc, and iron concentrations between foreign and local liquid milk samples.

The estimated daily intake (EDI) of iron from liquid milk exceeded the reference oral dose across all age groups, indicating a potential health risk. The hazard quotient (HQ) values for all metals in powdered milk were below one, suggesting no significant non-carcinogenic risk. However, the hazard index (HI) values exceeded one for several milk sample groups, indicating potential health risks to consumers, with the highest HI observed among females and powdered milk consumers.

The study concludes that heavy metal contamination of milk poses a significant public health concern. Continuous monitoring and strict regulatory control of both locally produced and imported milk are essential to assess dietary exposure to heavy metals and mitigate potential health risks.