A scientific basis for proposed quality assurance of a new screening method for tumor-like growths in the planarian, Dugesia dorotocephala.

: Various abnormal growths appear on planarians, Dugesia dorotocephala, during and after exposure to polychlorinated biphenyls (PCBs) 28, 110, and 126; Aroclor 1254; cadmium sulfate; and L-buthionine-(R,S)-sulfoximine (BSO). Daily observations under magnification were used to describe the location, development, and morphology of three different types of tumor-like growths ("tumors"). "Post-head tumors" were found to be highly invasive, progressive, and lethal to the animal depending on concentrations and combinations of the compounds used. Survivors from post-head tumors exhibited aberrant morphogenesis, but developmental abnormalities were eventually shed. Post-head tumors occurred within 2 weeks of initial exposure, while "round tail tip tumors" appeared after 2-3 weeks. The rate of progression and invasiveness was greater for the round tail tip tumors. "Pigmented rose thorn tail tumors" occurred in low incidence (4-20%) and appeared to be harmless and noninvasive, requiring months to develop from the first appearance of pigmentation. The aggressive, proliferative, and invasive characteristics of post-head and round tail tip tumors are analogous to those of malignant tumors, while pigmented rose thorn tumors were benign. High dose of cadmium alone were sufficient to initiate the post-head and round tail tip tumors. PCBs potentiated the tumorigenicity of low cadmium doses and enhanced the very low spontaneous incidence of pigmented rose thorn tumors. PCBs also impaired motor activity, causing the graceful gliding locomotion to be replaced by a twisting serpentine movement accompanied by muscular dystrophy. In addition, high (50 micrograms) doses of PCB 110 depressed activity, while lower (5 micrograms) doses and 50 micrograms Aroclor 1254 induced restlessness and enhanced locomotion. These data provide the basis for quality assurance.