Bull. Environ. Contam. Toxicol. (1996) 56:244-250 © 1996 Springer-Verlag New York Inc. Porphyrins as Biomarkers of Methylmercury and PCB Exposure in Experimental Quail C . Le o nzio , M. C . Fo ssi, S. C a sini Dipartimento di Biologia Ambientale, Università di Siena, Via delle Cerchia 3, 53100 Siena, Italy Received: 20 June 1994/Accepted: 21 August 1995 Chemicals such as heavy metals and polyhalogenated hydrocarbons have a high capacity to interfere with the enzymatic processes responsible for haem biosynthesis. These compounds can produce accumulation in tissues and organs and increased elimination of porphyrins in excreta (Andrew et al, 1990). The development of fast and easy analytical methods and the wide variety of biological media in which porphyrins can be detected have suggested their use as biomarkers of environmental pollution (Akins et al, 1993; De Matteis and Lim 1994). The analysis of porphyrins in the excreta is of special interest because it enables non- destructive monitoring of wild animals in the assessment of threatened or endangered species (Fossi et al, 1994). Methylmercury and PCBs are ubiquitous global pollutants and there is evidence they accumulate in terminal consumers, particularly those belonging to marine trophic chain (Renzoni et al, 1986; Yamashita et al, 1993). There have been some reports on methylmercury-induced (e.g. Woods et al, 1991; Bowers et al,, 1992; Miller and Woods 1993) and PCB-induced porphyria (e.g. Vos and Pennings, 1971; Miranda et al, 1987; Elliot et al, 1990; Miranda et al, 1992) but little data on their combined effect. In order to investigate the quality of porphyrins as biomarkers we performed an experiment in which Japanese quail were fed a diet containing methylmercury and polychlorobyphenyls (PCBs as Arochlor 1260) individually or combined in different ratios. The present study aims to provide preliminary data on liver and fecal levels of porphyrins in response to methylmercury and PCB administration, and on whether the indicator is sensitive to synergism or antagonism between the two compounds, administered simultaneously. MATERIALS AND METHODS Forty adult male Japanese quail (Coturnix coturnix japonica) were acclimatized and then divided into seven groups: a group of ten quails was kept as controls and the other 6 groups, each of five quail, were fed diets containing: 2.5 mg/kg of mercury as methylmercury (ME2.5), 25 mg/kg of mercury as methylmercury Correspondence to: C. Leonzio 244