Acute Toxicity of Lead, Steel, and an Iron-Tungsten-Nickel Shot to Mallard Ducks (Anas Platyrhynchos)

Abstract

Twenty mallards (Anas platyrhynchos) of both sexes were dosed by oral gavage with Heavi-Shot (H-S; Environ-Metal, Inc., Sweet Home, Oregon, USA) pellets, 20 with steel shot, and 10 with lead (Pb) pellets, all of equal size. All pellets were fired from a shotgun into an absorbent material, retrieved, and weighed prior to introduction into the ducks. Birds were fed whole kernel corn and grit and observed for signs of toxicity for 30 days following dosing. HeviShot pellets lost an average of 6.2% of their mass and steel shot pellets lost 57% of their mass in the birds' gizzards. Almost all (90%) of the Pb shot dosed birds died before the end of the study, while no mortality was observed in the steel or H-S dosed groups. Even though total food consumption differed between the H-S and steel shot groups, mean bird weight change was not different. There were no significant morphologic or histopathologic abnormalities of the liver and kidney in the H-S and steel shot groups. Results indicated that mallards dosed orally with eight No. 4 H-S pellets were not adversely affected over a 30-day period, and that H-S provides another environmentally safe nontoxic shot for use in waterfowl hunting.

Lead Toxicity in Captive and Wild Mallards (Anas Platyrhynchos) in Spain

“…The nonretention of some lead shot in the gizzard is normal. Brewer et al (2003) reported elimination of 8.8% of shot between days 4 and 22 after ingestion. The gradual reduction of shot size observed in our study, until its complete degradation by around day 30, also is normal and in agreement with previous studies (Srebocan and Rattner, 1988).…”

“…Shot pellets retained in the gizzard are ground by the abrasive action of grit and dissolved by the acid secretions of the proventriculus, with lead salts absorbed into the bloodstream (Mateo et al, 1997). The degree of metal erosion of individual shot in the mallard gizzard is directly correlated to the amount of metal that is available for uptake and circulation (Brewer et al, 2003). Differences in degradation can be related to varied diets used in experiments or other factors and should be considered when estimating prevalence of lead shot exposure based on gizzard examinations.…”

“…Given the increasing number of birds killed every year because of lead toxicosis, lead shot was banned for use in waterfowl hunting in the USA in 1991, and led to a subsequent decline in the rate of waterfowl poisoning (Brewer et al, 2003). Lead shot also has been banned in the wetlands of Andalusia (Spain) since 2002 (Mateo et al, 2007).…”

“…Lead shot also has been banned in the wetlands of Andalusia (Spain) since 2002 (Mateo et al, 2007). Lead shot has been replaced by alternative nontoxic shot made out of steel or other materials that contain a mixture of tungsten, nickel, and iron, and these types of shot have been well accepted by hunters (Mateo et al, 1998;Brewer et al, 2003).…”

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).…”