Overview
A twenty-year post-mortem monitoring programme at the Oostvaardersplassen (OVP) nature reserve in the Netherlands measured 13 trace elements and heavy metals by ICP-MS in the livers of 346 Heck cattle, red deer, and Konik horses, establishing species-specific reference intervals and documenting temporal trends in hepatic concentrations of lead (Pb), cadmium (Cd), arsenic (As), chromium (Cr), nickel (Ni), Co, Cu, Fe, Mn, Mo, Se, V, and Zn across 2003–2023.
Key numbers
Total n = 346: Heck cattle 167, red deer 96, Konik horses 83. LOQ (mg/kg dry weight): As 0.4, Cd 0.1, Cr 0.1, Co 0.1, Cu 1, Fe 10, Pb 0.1, Mn 0.1, Mo 0.1, Ni 0.1, Se 0.4, V 0.1, Zn 5.
Reference intervals for “non-indicative of disease” animals (mg/kg dw, 95% RI):
Heck cattle (n=38 for RI): Cu 2.0–70.5; Fe 232.9–2,578.2; Pb not quantifiable–4.6; Mn 6.1–14.6; Mo 0.6–6.4; Se not quantifiable–1.2; Zn 43.1–383.7. As, Cd, Cr, Ni, V were below LOQ in >50% of samples.
Red deer (n=57 for RI) and Konik horses (n=53 for RI): reported in Tables 4 and 5 of the source. Horses showed elevated Fe and Pb relative to cattle; red deer showed comparatively higher Cu. Temporal declines in Fe and Pb were statistically significant across all three species (p < 0.01), with additional year-related declines in Co, Cu, and Zn in cattle, and Cr, V, and Zn in horses.
Methods (brief)
Post-mortem liver sampling from carcasses submitted for pathological examination 2003–2023. Approximately 100 g liver homogenized, dried at 103°C for dry weight, digested in 65% HNO3 by microwave, diluted with ultrapure water, internal standards added (Ge, Sc, Tl). ICP-MS (Agilent). ISO 17025-compliant laboratory. Dry-weight basis throughout. As and Ni were >50% below LOQ in horses; As, Cd, Cr, Ni, V were >50% below LOQ in cattle and red deer, so these elements were excluded from regression and RI analyses for those species.
Note on arsenic: the paper reports total As by ICP-MS without speciation; values should be treated as total arsenic (tAs), not inorganic arsenic (iAs).
Implications
Certification: Heck cattle and red deer livers are sold as game or semi-wild meat products in Netherlands and broader EU markets. Pb concentrations (upper RI 4.6 mg/kg dw in cattle) and the temporal declining trend align with reduced environmental Pb inputs. Cd was detectable but majority of samples below LOQ (0.1 mg/kg dw). The study documents that livestock reference intervals do not apply directly to free-living herbivores, which is relevant to any certification program assessing game liver as a food matrix.
Courses: Illustrates environmental monitoring application of ICP-MS for long-term wildlife health and food-chain contamination trends.
App: Liver from free-ranging cattle and deer is a relevant food matrix for heavy metal occurrence; this study provides NL-specific baselines.
Related evidence
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