Abstract
The eco-exposome represents the totality of chemicals present in an organism. To understand how internal exposure of fish relates to chemicals originating from external media (water, sediment), we conducted a 21-d caging study using fathead minnow (Pimephales promelas, FHM) as model species. Four sites in/at Lake Superior were chosen that reflect sources of two broad groups of environmental contaminants: Two pond sites with a legacy contamination by persistent organic pollutants (POPs), one site close to a wastewater treatment plant (WWTP) outlet showing more recent and regularly discharged compounds, and one creek expected to show a mixed contamination from both compound groups. We determined total water concentrations, freely dissolved concentrations in sediment pore water, and the FHM's body burden of organic micropollutants after 2 and 21 d of exposure. Of the 456 target compounds analyzed in FHM, 123 were quantified in water, 165 in sediment and 100 in FHM tissue samples. Chemical profiles and concentrations at the different study locations varied according to their classification as legacy or recently contaminated sites, with the site impacted by the WWTP showing the highest overall concentrations. Only 77 substances quantified in FHM were also detected in water and/or sediment and after applying additional quality and consistency measures, 37 of the 100 substances detected in FHM could not be directly linked to water and/or sediment. Therefore, chemical concentrations in water and sediment cannot simply predict the eco-exposome in fish, which underscores the need of body burden analysis to comprehensively understand an organism's exposure.