Contaminants in caribou tissues from northern Québec

Abstract

Recent findings that cadmium, an atmospheric pollutant, was present at relatively high concentration in cervids from southern Québec triggered a study on contamination of caribou tissues. Following the Chernobyl accident, caribou tissues were also investigated for radionuclides. Cadmium concentrations varied according to organ, age, sex and time of collection. In fall, it averaged 27.5 (S.E. = 3.5; n= 50), 2.3 (0.3;40), and 0.1(0.01;17)/u.g • g" 1 (dry weight) in the kidneys, liver and rumen wall respectively; in skeletal muscles and the heart, mean concentrations reached 0.002 (0.001;33) and 0.003 (0.003;7) fxg • g" 1. Lead and mercury were measured in the liver for a smaller number of animals; concentration averaged 1.4 (0.2;41) and 0.7 (0.03;41) (xg • g _1 (dry weight) for the first and the second element respectively. In general, cadmium and mercury levels were higher in Québec animals than in those from Norway, while concentrations were comparable for lead. Only 10-15 percent of cesium 137 present in northern Québec originated from Chernobyl, the rest being due to earlier atmospheric nuclear weapon testing. Among tissues examined, kidneys contained the highest cesium level, followed by skeletal muscles. Mean cesium concentrations in caribou meat varied between 166 (16;4) and 1129 (74;9) Bq • kg" 1 (wet weight) according to area and month of collection. Caribou feeding habits and regional variation in lichen contamination may explain oberved differences. Those cesium levels were the highest observed throughout northern Canada in 1986-1987. In Québec, the consumption of caribou kidneys and liver is not recommended mainly because of cadmium; consumption of caribou meat poses limited risks with respect to heavy metals or cesium but other natural and artificial radionuclides must be measured before making final recommendations.

Levels of Cadmium, Lead, Mercury and 137caesium in Caribou (<i>Rangifer tarandus</i>) Tissues from Northern Québec

“…Mean Cd concentrations measured in kidney, liver, and muscle of caribou from the GRTM region were lower than those reported a few years earlier in the same region (liver: 1.2 -2.9 µg • g -1 ; kidney: 11.7-40.7 µg • g -1 ; muscle: 0 -0.20 µg • g -1 ; . Mean Pb concentrations in liver were also lower than those reported in the earlier study from the GRTM region (1.1 µg • g -1 ; Crête et al, 1990). Mean Pb concentrations in our kidney samples were similar to those found in caribou from the Northwest Territories (0.20 -2.7 µg • g -1 ), but concentrations in our liver samples were generally higher than those from caribou in the Northwest Territories (0.07 -0.34 µg • g -1 ; Elkin and Bethke, 1995).…”

“…Total mercury liver concentrations from the LR region were smaller than earlier levels found in the same region (0.5 µg • g -1 ; Crête et al, 1990). Levels found in the GRTM regions must therefore have decreased to an even greater extent.…”

“…Not surprisingly, age was associated with kidney log Cd levels. In other cervids, older animals usually exhibit higher levels (Wolf et al, 1982;Froslie et al, 1986;Crête et al, 1989Crête et al, , 1990Eriksson et al, 1990;Stansley et al, 1991;Rintala et al, 1995;Borch-Johnsen et al, 1996). Continued retention is known to induce a progressive accumulation of Cd in soft tissues, particularly in kidneys (Goyer, 1991).…”

“…Moreover, the Chernobyl accident, which occurred in 1986, resulted in a 14 -15% increase in concentrations of fission-related isotopes in Canadian Arctic lichens (Taylor et al, 1988). The presence of anthropogenic heavy metals, such as cadmium (Cd), lead (Pb) and mercury (Hg), and radioisotopes, such as 137 caesium ( 137 Cs), has been documented in different wildlife species in these remote regions (Crête et al, 1987(Crête et al, , 1989(Crête et al, , 1990(Crête et al, , 1993Thomas et al, 1992, Gamber andScheuhammer, 1994;Elkin and Bethke, 1995;Langlois and Langis, 1995;Kim et al, 1998;Braune et al, 1999;Aastrup et al, 2000;Larter and Nagy, 2000).…”

“…Although caribou are harvested from different regions in northern Québec, regional trends in toxic compound levels have not been investigated in the area. Crête et al (1989Crête et al ( , 1990 focused primarily on the caribou herd belonging to the George River region. Harvested caribou may also originate from the more westerly Leaf River region.…”