In this report we assess lead contamination of seabirds from the use of lead shot in Greenland. We have studied thick-billed murre and common eider, the two most important species to seabird hunting, and we evaluate the human lead intake from contamination with lead shot.

In an earlier study we found that the use of lead shot was a significant lead source in the diet of many people in Greenland. The study indicated that lead in the meat exists as small lead fragments, left during the passage of pellets through the breast. However, because of an inhomogeneous lead distribution in samples, the uncertainty of the estimated lead concentration in breast meat was high in the study, in which only a sub-sample of about 1-gram was analyzed.

In this new study we have intended to obtain a more reliable estimate of the human lead exposure. We have done this by analyzing whole breasts from murres. By doing this, all lead fragments in the breast will be included in the chemical analysis. The study showed that the mean lead concentration in whole murre breasts is about 4 times higher than we found when we analyzed 1-gram sub-samples from the same birds.

The lead concentration is low in breasts from eiders killed by drowning, whereas it is very high in eiders killed with lead shot (mean lead concentration 6.1 µg/g wet wt). This level is significantly higher (a factor of about 8) than in murre, and it is much higher (a factor of 44) in eiders killed with lead shot than in drowned birds. In murres 11% of the observations exceed Danish and Canadian residue guidelines for lead, whereas in eiders this is the case for more than half of the birds analyzed.

A calculation of the human lead intake from the diet shows that birds killed with lead shot is a significant lead source, probably the most important single source, of lead in the diet of Greenland population. The highest exposure must be expected in Southwest Greenland during winter, when most seabirds are killed on their wintering grounds. One single eider meal will result in a mean lead intake, which is almost 6 times higher than FAO/WHO's value for "tolerable lead intake" on a daily basis. One murre meal will result in a mean lead intake of 68% of this value.

We have also analyzed wingbones from the eiders, as the lead concentration in bone tissue is considered a good indicator for lead exposure over the lifetime of the individual. We found a low lead level in bones, indicating that the eiders only accumulate lead to a small degree and that lead has no toxic effect on the birds.

	Full report in pdf format (761 KB)

2002-09-13