Toxic Chemical Pollution: 2001
Skaare, J.U., Bernhoft, A., Wiig, O., Norum, K.R., Haug, E., Eide,
D.M., and Derocher, A.E.
Title: Relationships between plasma levels of
organochlorines, retinol and thyroid hormones from polar bears
(Ursus maritimus) at Svalbard.
Publication: Journal of Toxicology and
Environmental Health Part A 62(4): 227-241, 2001.
© Taylor & Francis
were determined between retinol and the thyroid hormones thyroxine
(T4) and triiodothyronine (T3), respectively, and the
organochlorine contaminants (OCs) polychlorinated biphenyls
(PCBs), 1,1-dichloro-2,2-bis-(4-chlorophenyl)ethylene (DDE),
hexachlorobenzene (HCB), and hexachlorocyclohexanes (HCHs) in
blood plasma from polar bears (Ursus maritimus) caught at
Svalbard. The blood samples were collected from free-ranging polar
bears of different age and sex in 1991-1994. The retinol
concentration and the ratio of total T4 (TT4) to free T4(FT4)
(TT4/FT4 ratio) decreased linearly with increasing concentrations
of PCBs and HCB. Retinol was also negatively associated with HCHs,
while the TT4/FT4 ratio was positively associated with DDE. The
concentrations of retinol and thyroid hormones were significantly
higher in females than in males. However, the TT4/FT4 and TT3/FT3
ratios were significantly higher in males than in females. The
concentrations of thyroid hormones were negatively correlated with
age in male bears, while in females, thyroid hormones did not
change with age. The OCs were found to explain 12, 30, and 7% of
the variation of retinol concentrations and the TT4/FT4 and
TT3/FT3 ratios, respectively, after correcting for age and sex.
The potential consequence of these associations for the individual
and the population is unknown.