Summary
This study measured concentrations of eight potentially toxic elements (cadmium, arsenic, chromium, nickel, lead, manganese, copper, and zinc) in paired liver and muscle samples from broiler chicken, goat, and beef cattle collected from slaughterhouses and retail markets in Peshawar, Islamabad, Gujrat, and Lahore, Pakistan (92 paired samples from 2022 to 2023). Analysis was by ICP-MS (Agilent 7500cx). Zinc and copper had the highest concentrations overall; arsenic, lead, nickel, and cadmium occurred at lower but environmentally relevant levels. Beef liver exhibited the highest contamination levels, exceeding FAO/WHO permissible limits for lead, copper, and cadmium in up to 40% of samples. Under high-consumption scenarios, THQ values for arsenic, chromium, copper, and zinc exceeded the safety threshold (greater than 1), highlighting beef products as a source of chronic dietary risk. Principal component analysis revealed three dominant contamination co-variation patterns: geogenic groundwater enrichment (arsenic, chromium, nickel); atmospheric and industrial dust (lead, cadmium, manganese); and mineral-enriched feed additives (zinc, copper).
Key numbers
| Measure | Value | Units | Matrix | Source location |
|---|---|---|---|---|
| arsenic (As) median, mutton muscle | 83.8 | µg/kg dry weight | Mutton muscle | p. 7, Figure 2 |
| arsenic (As) median, mutton liver | 29.1 | µg/kg dry weight | Mutton liver | p. 7, Figure 2 |
| FAO/WHO ML, lead (Pb) in liver | varies by species | mg/kg | Reference | p. 3 |
| cadmium (Cd) in up to 40% of beef liver samples exceeds FAO/WHO limit | 40% | percentage exceedance | Beef liver | Abstract |
| Cu in up to 40% of beef liver samples exceeds FAO/WHO limit | 40% | percentage exceedance | Beef liver | Abstract |
| lead (Pb) in up to 40% of beef liver samples exceeds FAO/WHO limit | 40% | percentage exceedance | Beef liver | Abstract |
| THQ greater than 1 for arsenic (As), chromium (Cr), Cu, Zn under high consumption | greater than 1 | dimensionless | Beef consumers | Abstract |
| Ingestion rate, chicken muscle (high consumption) | 500 | g per day | Reference scenario | Methods |
| Ingestion rate, mutton and beef (high consumption) | 250 | g per day | Reference scenario | Methods |
| Annual per capita meat consumption (Pakistan) | 32 | kg per year | National estimate | p. 2 |
| Sample n (total) | 92 | paired liver/muscle samples | 4 cities | Methods |
| Recovery range | 80 to 104% | percentage | QC | Methods |
Arsenic concentrations in mutton muscle (median 83.8 µg/kg dry weight) were significantly higher than in liver (29.1 µg/kg dry weight) (p less than 0.05), suggesting distinct tissue distribution pathways for arsenic. Mutton and beef muscle contained the highest arsenic and zinc concentrations. Chicken muscle showed elevated chromium levels.
Methods (brief)
92 paired fresh meat samples from slaughterhouses and farms in Peshawar, Islamabad, Gujrat, and Lahore, January 2022 to December 2023. Liver and muscle separated for each sample. Dried at 60 degrees C for 24 hours, ground, digested with 2 mL 65% HNO3 and 1 mL 35% H2O2 overnight then 800 W, 120 degrees C/10 minutes then 800 W, 170 degrees C/30 minutes (microwave, Mars CEM). ICP-MS (Agilent 7500cx). CRM: IAEA-350 Tuna Fish Flesh Homogenate. Recovery 80 to 104% for all elements. LODs: cadmium (Cd) and As at µg/kg level, chromium (Cr), nickel (Ni), lead (Pb) at µg/kg level (see Table S1 for specific values). Statistical analysis: SPSS v27, Shapiro-Wilk, log transformation, Kruskal-Wallis H test.
Evidence fitness
This is a multi-city, multi-species, paired tissue study that provides evidence on tissue-specific accumulation differences across the main meat types consumed in Pakistan. The beef liver finding, with up to 40% exceedance of FAO/WHO limits for lead, copper, and cadmium, is a food safety concern for offal consumers. The arsenic and chromium THQ exceedances under high-consumption scenarios identify a risk pathway relevant to both Pakistani consumers and food safety regulators. PCA source apportionment distinguishes geogenic from anthropogenic contamination drivers.
Limitations
Sampling is market-based, not formal random probability sampling, so results are interpreted as screening-level representation. All concentrations on dry-weight basis; conversion to fresh-weight needed for comparison with regulatory limits typically expressed on wet-weight basis. Arsenic speciation not performed; total arsenic used in carcinogenic risk calculation may overstate risk.
Related evidence
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