Distribution paths of endocrine disrupting phenolic compounds in waterbirds (Mergus merganser, Alca torda, Clangula hyemalis) from the Southern Baltic

Abstract

This study determined the distribution of phenol derivatives in the organisms of waterbirds and the factors influencing their bioaccumulation and affinity to specific tissues. Concentrations of bisphenol A (BPA), 4-tert-octylphenol (4-t-OP) and 4-nonylphenol (4-NP) were determined in the brains, subcutaneous fat, kidneys, livers and pectoral muscles of goosanders Mergus merganser (GO), long-tailed ducks Clangula hyemalis (LO) and razorbills Alca torda (RA). The birds came from the winter by-catch (2014-2016) in the Southern Baltic. Different distribution routes of individual phenol derivatives in the birds were established, most likely due to their ability to bind to proteins and/or dissolve in lipids. BPA and 4-NP accumulated most in the muscles (BPA <2.0-223.0 ng^.g^-1 dw, 4-NP 26.0-476.4 ng^.g^-1 dw), livers (BPA <2.0-318.2 ng^.g^-1 dw, 4-NP 60.7-525.8 ng^.g^-1 dw), and kidneys (BPA <2.0-836.1 ng^.g^-1 dw, 4-NP 29.3-469.2 ng^.g^-1 dw), while 4-t-OP was stored mainly in the brains (2.6-341.1 ng^.g^-1 dw), subcutaneous fat (0.7-173.7 ng^.g^-1 dw) and livers (<0.5-698.8 ng^.g^-1 dw). The liver was the only organ where all compounds showed a positive correlation with each other and alkylphenols were also positively correlated with each other in tissues with high fat content (brains and subcutaneous fat), and negatively in muscles. Despite the different trophic levels of birds, the concentrations of phenol derivatives in the tissues between individual species in most cases did not differ significantly. However, between the species on a similar trophic level, the higher biomagnification coefficient was calculated for LO feeding on benthos, and the lower for RA feeding on pelagic fish (p < 0.05). The good condition of birds, resulting in large intestinal fat stores, promoted on the one hand the penetration of phenol derivatives from the intestine to the liver, and on the other hand their accumulation in subcutaneous fat, thereby protecting the brain.

Keywords: Bisphenol A and alkylphenols; Brain; Kidneys; Liver; Muscles; Subcutaneous fat.