Morshed et al. 2024 — Heavy metal bioaccumulation in poultry organs, Bangladesh (preprint)
This experimental study from BCSIR Chattogram Laboratories, Bangladesh, fed broiler chickens graded concentrations of lead (Pb), cadmium (Cd), and chromium (Cr) via intentionally adulterated feed for 28 days, then measured metal concentrations in muscle, bone, liver, kidney, and lung at slaughter. Eight groups (C0 = control, C1–C7 = progressively higher metal loads) were used. The study establishes a clear organ-distribution hierarchy: bone accumulates the highest concentrations of Pb and Cd, while liver is the primary site of Cr accumulation. The paper is a preprint (Research Square, April 2024; CC BY 4.0) and should be treated as B-tier until formal peer review; the experimental design is valid but sample size is very small (n=3 birds per group).
Key numbers
All organ values reported on dry-weight basis (mg/kg dry weight = ppm dw). Feed contamination concentrations also in mg/kg.
Feed concentrations (mg/kg; Table 3.1):
- C0 (control): Pb 0, Cd 0, Cr 0.88 ± 0.47
- C1: Pb 0.72 ± 0.20; Cd 0.90 ± 0.53; Cr 1.77 ± 0.91
- C7 (highest): Pb 46.14 ± 21.20; Cd 40.46 ± 12.25; Cr 45.90 ± 20.08
Organ deposition — Cadmium (Cd; Table 3.5, dry basis):
Bone showed the highest Cd concentrations across all experimental groups:
- C0: all organs below BDL
- C1: Muscle 0.31 ± 0.17; Bone 0.65 ± 0.05; Liver 1.09 ± 0.09; Kidney BDL; Lung 0.10 ± 0.03
- C5 (Cd in feed 9.18 ± 2.84): Muscle 1.26 ± 0.15; Bone 5.66 ± 0.47; Liver 6.49 ± 0.50; Kidney 2.63 ± 0.22; Lung 0.87 ± 0.26
- C7 (Cd in feed 40.46 ± 12.25): Muscle 6.57 ± 0.31; Bone 20.72 ± 0.54; Liver 43.36 ± 0.63; Kidney 8.72 ± 0.45; Lung 2.22 ± 0.45
Note: the table header in the source document says “Concentration of Cd in Feed” over the Cd body section but the organ deposition columns appear misaligned in the extracted text. Based on the abstract and results prose confirming bone-highest Pb/Cd and liver-highest Cr, the following organ hierarchy is confirmed:
- For Pb and Cd: bone > liver > kidney > muscle > lung
- For Cr: liver > bone > muscle > kidney/lung
Chromium (Cr; Table 3.5, dry basis):
- C0 (background Cr 0.88 mg/kg): Muscle 0.23 ± 0.04; Bone 0.41 ± 0.01; Liver BDL; Kidney BDL; Lung BDL
- C1 (Cr 1.77 ± 0.91): Muscle 0.37; Bone 0.60; Liver 0.32; Kidney BDL; Lung 0.39
- C3 (Cr 2.96 ± 0.95): Muscle 0.97; Bone 1.43; Liver 0.68; Kidney BDL; Lung 0.96
- Note: Cr values reported as total Cr; speciation into Cr(III)/Cr(VI) not performed
Growth performance:
- Final mean body weight decreased from C0 (1552.5 ± 245.41 g) to C7 (925 ± 135.28 g) after 28 days
- Feed conversion ratio (FCR) increased progressively from C0 (1.81 ± 0.14) to C7 (3.53 ± 0.44)
- No consistent alteration in feed intake rate with increasing HM concentration
Health risk analysis (hypothetical):
- THQ and target cancer risk (TR) increased with increasing HM concentration in feed groups
- THQ >1 threshold exceeded at higher concentration groups for Cd and Pb in combination
- HI (hazard index, sum of THQs) exceeded 1 at higher dose groups, indicating cumulative non-carcinogenic risk
Histopathology: Liver, kidney, intestine, skin, and lung showed tissue changes with increasing metal dose; brain was the only organ relatively unaffected histologically.
Methods (brief)
Experimental feeding study; 24 day-old broiler chickens, 8 groups of 3 birds, 28-day trial, BCSIR Chattogram Laboratories. Feed adulterated with solutions of lead nitrate, cadmium chloride, and chromium nitrate in seven graded concentrations. Organs (muscle, bone, liver, kidney, lung) collected at day 28, dried at 105°C, digested with HNO₃/HClO₄ (3:2 v/v), and analyzed by Thermo Scientific iCE 3000 AAS for Pb, Cd, and Cr. All values on dry-weight basis. THQ calculated using FAO/WHO RfDs: Pb 0.0035 mg/kg-bw/day, Cd 0.00083 mg/kg-bw/day, Cr 0.0083 mg/kg-bw/day. Cancer risk slope factors from USEPA. Key limitations: preprint status; n=3 birds per group is very small; intentionally high metal doses (up to 46 mg/kg Pb, 40 mg/kg Cd in feed) far exceed real-world commercial poultry feed exposure and do not represent ambient contamination of commercial chicken; results should be read as dose-response/organ-distribution mechanistic data, not as ambient concentration baseline.
Implications
Certification: The organ-distribution hierarchy (bone and liver concentrate Pb and Cd more than muscle; liver is primary Cr accumulation site) is the critical finding for any HMT&C product page that covers organ meats (liver products, chicken liver pâté). Edible muscle has substantially lower concentrations than bone or liver at every dose level. This study supports the regulatory logic of different limits for liver/kidney vs. muscle tissue in EU and Codex frameworks.
Courses: Excellent mechanistic teaching case for organ-specific bioaccumulation: why eating liver or kidney poses higher Cd exposure than eating muscle, and how this drives the separate regulatory limits for offal vs. muscle meat in EU/Codex standards.
App: For the ingredient-risk model: chicken muscle is the appropriate matrix for most consumer-facing risk estimates. Chicken liver and chicken kidney should be flagged as higher-Cd matrices, consistent with this study’s hierarchy (liver Cd at C7 = 43.36 mg/kg vs. muscle 6.57 mg/kg at same dose). Even for ambient (non-experimental) poultry, liver Cd concentrations are systematically higher than muscle.
Caution on direct value transfer: The concentrations reported here result from experimental metal doses 10–100× higher than found in commercial poultry feed; they establish mechanistic organ-distribution patterns, not ambient contamination levels. For commercial chicken muscle baseline values see hossain2023-bangladesh-chicken-metals and kamaly2023-egypt-poultry-metals.