Residue levels of several organochlorines in Tursiops truncatus milk collected at varied stages of lactation

The concentrations of several organochlorines (OCs) were measured in the milk of five healthy bottlenose dolphins, Tursiops truncatus, of various ages and reproductive histories. These dolphins were trained to position at penside to allow for milk collection; samples were collected at various stages of lactation. The highest values in ppm wet weight (lipid weight in parentheses) were: 10.2 (32.4) p,p′-DDE, 0.586 (1.86) p,p′-DDD, 0.251 (0.797) p,p′-DDT and 4.45 (14.1) PCB (as Aroclor 1254), and were found in milk produced by the oldest dolphin (age 34) during what was probably its first, and orphan-induced, lactation. The lowest values recovered were: 0.330 (1.62) p,p′-DDE, 0.027 (0.132) p,p′-DDD, < 0.025 p,p′-DDT and 0.0281 (1.38) PCB, found in milk produced by one of the youngest dolphins (age 16). These data suggest that OCs may be released at levels related to age, reproductive history and lipid content of milk. The collection technique used allows for a serial study without animal injury or mortality.