The occurrence of EDCs (OP, NP, BPA, and E1) and estrogenic activities were investigated in the water, suspended solids, sediments, and fish from the Nan River, Phitsanulok, Thailand. The samples were collected from 12 sites along the Nan River, which was divided into 3 zones as upstream, midstream (municipality area) and downstream. Gas chromatography-mass spectrometry (GC-MS) was used to determine EDCs concentrations and yeast estrogen screen (YES) bioassay was used to test for estrogenic

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... vity. The results from this study showed that in water samples, OP, NP, BPA, and E1 were found in ranges of 0.87-10.09 ng/L, 179.63-1,164.41 ng/L, 34.97-1,554.14 ng/L, and ND-9.73 ng/L, respectively. In sediment samples, NP, BPA, and E1 were found in ranges of 5.55-35.60 ng/g, 5.15-7.62 ng/g, and 1.32-11.31 ng/g, respectively, while OP not detected at all sites. In suspended solids samples, OP, NP, BPA, and E1 were found in ranges of 4.04-18.03 ng/L, 225.29-554.90 ng/L, 10.80-22.61 ng/L, and 6.48-22.28 ng/L, respectively. In addition, in fish samples, OP, NP, BPA, and E1 were found in ranges of 62.40-600.98 ng/g, 5,623.75-5,7281.48 ng/g, 9.04-44.12 ng/g, and 5.62-133.82 ng/g, respectively. For the results of estrogenic activities in terms of the EEQ for water, sediment, suspended solids, and fish samples were found in ranges of 0-0.985 ngEEQ/L, 0-0.168 ngEEQ/g, 0-0.391 ngEEQ/L, and 0.087-0.873 ngEEQ/g, respectively. Risk assessment of EDCs present in water, sediments, suspended solids, and fish indicated low to medium risk.