Levels and implications of polychlorinated hydrocarbons in male Australasian harriers

Breast tissues from four male Australasian harriers (Circus approxmans) were analysed for polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) pesticides at the AgriQuality Environmental ultra-trace analytical unit. The harriers were injured birds collected and euthanased over the period from 1998 to 1999 by Bird Rescue Wanganui-Manawatu. The total toxic equivalents (I-TEQ) considering all the PCDD/F and PCB congeners, ranged from 3.7 to 47.7 pg/g wet weight. While these I-TEQ values are higher than previously reported for New Zealand avian species, the values are relatively low when compared to the concentrations in raptors that have been reported internationally. The I-TEQ values in Australasian harriers were dominated by the PCB congeners, contributing approximately 65% of the I-TEQ. This finding is consistent with previous studies on New Zealand avian species and recent studies examining the congener compositions of raptor samples. The dominant PCB congeners in the harrier samples were congeners #153, #138 and #180. The highest concentration for a PCB was 65 ng/g wet weight for congener #153. The only congener that was below detection limits in all samples was #81. The PCB congeners with the highest toxic equivalency factor (TEF) values #126, #77 and #169 were present at concentrations in the approximate range of 0.1 to 0.01 ng/g wet weight. The dominant PCDD/F congeners were OCDD and 1,2,3,6,7,8-HxCDD, while 1,2,3,4,6,7,8-HpCDD and OCDF were also found in high concentrations compared to the remaining congeners. The highest concentration for an individual congener was 24 pg 1,2,3,6,7,8-HxCDD /g wet weight. The only analysed congener that was below detection limits in all samples was 1,2,3,7,8,9HxCDF. Although three of the four sample residues in this study exceeded the adopted reference dose of 7 pg I-TEQ /g, it is unlikely that the current levels of PCDD/ Fs and PCBs in Australasian harriers are causing population level effects. Nevertheless, the data suggest that there is little environmental assimilative capacity for I-TEQ.