Mechanical, Chemical, Structural, and Radiological Changes in Pigeon Bone, Associated with The Dietary Intake of Nickel Recovery Slag

Article history: Received 22 June 2019 Accepted 05 July 2019 Available online 15 July 2019 Slag from nickel smelting operations in the Sudbury basin in Ontario, Canada, has become ubiquitous. This material rich in heavy metals such as iron, upon ingestion has the potential to effect physical, radiological, chemical, mechanical, and structural changes in biological systems. In this work, we analyzed the effects of slag ingestion through diet, on several quantitative and qualitative parameters of the tibio-tarsal bones in pigeons (Columbia Livia Domestica). The specimens were maintained on a seed diet and divided into a control group (n = 9) provided (normal) clean limestone grit, and an experimental group (n = 9) provided slag-based grit, both for a period of one year. Their tibio-tarsal bones were harvested for analysis. Quantitative analytical methods included conventional density measurements, caliper-based cortical thickness measurements, bone mineral density measurements using Dual Energy X-ray Absorptiometry (DEXA), calcium and iron concentration measurements using mass spectrometry, and the determination of Young’s Moduli and ultimate breaking strength (both in compression) using a universal testing machine (UTM). Qualitative microscopy studies, both optical and electron including energy dispersive spectroscopy (EDS) were carried out for both sample groups. A Welch’s t-test (single tail) was used to compare means of the seven quantitative parameters between control and experimental samples; in six of these parameters, a statistically significant difference was found (p ≤ 0.05). Microscopy, both optical and electron coupled with EDS analysis revealed structural differences in bone between the two groups. Engineering hardness testing of grit types in the dietary components revealed that the slag ingested by the experimental group was approximately twice as hard (Brinell and Rockwell hardness) as the limestone grit in the control group diet. We conclude that slag ingestion through diet in the species examined, is associated with measurable changes in mechanical, chemical, structural, and radiological properties of the tibio-tarsal bones.