Effects of Embedded Tungsten-Bismuth-Tin Shot and Steel Shot on Mallards (Anas Platyrhynchos)

Abstract

We assessed the potential for embedded steel and tungsten-bismuth-tin (TBT) shot to adversely affect health of mallards (Anas platyrhynchos). Ducks were implanted with three number four steel (n = 19) or TBT (n = 20) shot pellets in their pectoral muscles. None of seven hematology parameters measured differed in response to treatment (P > or = 0.17). At necropsy 1, 2, 4, and 8 wk posttreatment, we observed only localized tissue reactions to embedded steel or TBT shot. Reactions differed grossly: after wk 1, embedded steel shot were enveloped in 0.5 to 2 mm grayish capsules, whereas TBT shot were surrounded by thinner (< 0.5 mm), translucent capsules. Corrosion of steel shot was apparent. Microscopic lesions associated with steel shot were characterized by moderate to severe histiocytic and lymphocytic inflammation and considerable particle deposition, whereas histiocytic inflammation was mild and particle deposition minimal in TBT lesions. Overall scores of inflammation at steel shot implant sites were greater (P < or = 0.043) than at TBT sites during wk 1 and 8. Inflammation at steel implant sites was relatively consistent over the 8-wk period, but decreased (P = 0.0017) at TBT sites by wk 8. Weights of steel shot recovered from muscle tissue declined logarithmically (R2 = 0.978, P = 0.0014) over 8 wk, but TBT shot weights remained unchanged (P = 0.255). Embedded TBT shot, as compared to steel, resisted corrosion and induced comparatively mild inflammatory responses in mallard muscle tissue. However, inflammatory reactions to both embedded steel and TBT shot were localized and had no detectable systemic effects on mallard health under experimental conditions.

Self‐organization of “fibro‐axonal” composite tissue around unmodified metallic micro‐electrodes can form a functioning interface with a peripheral nerve: A new direction for creating long‐term neural interfaces

“…The initial stage of reactive exudate formation on the material surfaces is followed by organization of the exudate into a stable capsule composed of fibroblasts and collagen fibers. [22][23][24][25] Based on our observations, we infer that the inflammatory response to the silicone and tungsten surfaces resulted in stable fibro-collagenous tissue encapsulation of the silicone tube and the micro-wires…”

Embedded Metal Fragments

“…Primarily, these investigations have focused on the safety of implanted medical devices (International Agency for Research on Cancer [IARC], 1999) and the development of "nontoxic" hunting ammunition (Brewer, Fairbrother, Clark, & Amick, 2003;Kelly et al, 1998;Kraabel, Miller, Getzy, & Ringelman, 1996;Mitchell et al, 2001a;Mitchell et al, 2001b;Mitchell et al, 2001c). Little has been done throughout the years to assess the long-term health effects of military-relevant metals and metal mixtures (Kane, Kasper, & Kalinich, 2009).…”

“…These fi ndings reinforced the primary caveat when designing studies with embedded fragments: The material under investigation must be identical, in terms of composition and manufacturing processes, to that found in the fi eld. For example, tungsten-containing hunting ammunition was found to have no adverse health effects when surgically implanted into the muscles of mallards (Kraabel et al, 1996); however, military-grade tungsten alloy compositions induced rhabdomyosarcomas when implanted into the leg muscles of laboratory rodents. Although both these compositions contained primarily tungsten with smaller concentrations of transition metals, they were not manufactured using similar procedures.…”

Assessment of the environmental toxicity and carcinogenicity of tungsten-based shot,

“…Should any tumours have developed within the 30 or 150 day 7 period, legal approval would not have been given. In a separate study, tungsten-bismuth-8 tin shot, when embedded in muscles of mallard ducks for eight weeks, did not produce 9 any adverse or toxic effects (Kraabel et al, 1996). To date, only the study by Kraabel et 10 al.…”