Several approaches to monitor the bioavailability and ecotoxicity of pentachlorophenol (PCP) in sterile and non sterile soils as a function of aging are reported. Porapak resins and water were used to assess the bioaccessibility and the bioavailability of PCP in soil. Aging effects were observed mainly after 240 d of aging. Actual bioavailability, measured as PCP bioaccumulation in earthworms, decreased more markedly with time. The ecotoxicological biomarker neutral red retention time (NRRT) displayed a dose dependent effect but no aging effects after exposing the earthworms to polluted soils. Nevertheless, mortality of earthworms increased after 240 d at 150 mg kg(-1) contamination. In contrast, the luminescent biosensor Pseudomonas fluorescens pUCD607 evidenced in non sterilized samples a slight reduction of ecotoxicity in time related to the degradation of the molecule. Once again, results highlight the necessity to study the fate of soil pollutants with different chemical and biological approaches. Different PCP degradation pathways and/or the different sensitivity of earthworms and bacteria could explain the different behaviours observed.