Organic ultraviolet filters in Irish sediments and biosolids

This study provides baseline data on the concentrations of selected ultraviolet filters (UVFs) in 81 inland and transitional sediments as well as in 21 agricultural biosolid samples sourced from seven wastewater treatment plants (WWTP) across Ireland. Concentrations of five prominent UVFs were determined: 4-methylbenzylidene camphor (4-MBC); benzophenone-3 (BP-3); 2-ethylhexyl-4-methoxycinnamate (EHMC); homosalate (HMS); and Octocrylene (OC). Mean concentrations in sediments were as follows: OC (3.66 ng/g); HMS (2.35 ng/g); 4-MBC (1.87 ng/g); BP-3 (0.19 ng/g); and EHMC (0.04 ng/g). Based on 95th percentile concentrations in sediments (MEC₉₅), HMS, EHMC, and 4-MBC were found to pose moderate ecotoxicological risk. Concentrations found in Irish sediments were found to be low compared to similar studies internationally. Arithmetic mean concentrations of UVFs in Irish biosolids were: OC (666 ng/g); HMS (453 ng/g); 4-MBC (13.9 ng/g); EHMC (12.7 ng/g); and BP-3 (1.28 ng/g). Fewer international data are available for these UVFs in biosolids, though available results indicate Ireland to have low levels compared to those found internationally for EHMC, 4-MBC, BP-3, and OC. This study is one of the first to report of concentrations of HMS in WWTP-derived biosolids and highlights the need for similar assessments internationally based on levels found in biosolids as well as in sediments. Ongoing monitoring in sediment is required for HMS and 4-MBC following their restrictions under the EU's Cosmetic Products Regulation (CPR), to ensure that environmental levels fall to levels concomitant with low ecotoxicological risk. Meanwhile, further assessments are required for OC, EHMC, and BP-3 to facilitate thorough evaluation of their environmental risks.