Use of multiple lines of evidence to provide a realistic toxic substances control act ecological risk evaluation based on monitoring data: D4 case study

Abstract

D4 (octamethylcyclotetrasiloxane) is a high-production-volume cyclic volatile methyl siloxane with a wide range of industrial and consumer applications. This study conducted a robust ecological risk evaluation for D4 using exposure data collected under a nation-wide environmental monitoring program facilitated under the Toxic Substances Control Act (TSCA). This ecological risk evaluation was conducted consistent with the principles outlined in the U.S. Environmental Protection Agency's (EPA's) Guidance to Assist Interested Persons in Developing and Submitting Draft Risk Evaluations under TSCA (U.S. EPA 2017a). The evaluation examined multiple lines of evidence (LoEs) to determine the potential risks from D4 to aquatic receptors in rivers and streams in the United States from municipal wastewater treatment plant (WWTP) discharges and discharges from manufacturing, processing, and/or formulating (MPF) facilities after onsite wastewater treatment. The LoEs consisted of comparing D4 concentrations measured in water and sediment to toxicity thresholds derived from laboratory studies; comparing D4 concentrations measured in biota tissue to critical target lipid body burdens (CTLBBs); comparing fugacity-based chemical activities between toxicity thresholds and measured environmental concentrations; and assessing benthic macroinvertebrate community structure and habitat suitability. The approach taken moves beyond a standard deterministic hazard quotient approach to incorporate more advanced methods for risk prediction, using distributions rather than conservative point estimates of exposure to obtain a realistic view of the probability of harm, consistent with EPA's stated intent to "strive to utilize probabilistic approaches for exposure assessments included in a risk evaluation" (U.S. EPA 2017b). The risk evaluation concluded there is negligible risk to water column and sediment receptors from D4 discharged from MPF facilities after onsite wastewater treatment or from municipal WWTPs that may treat a mix of industrial and consumer wastewater.

Ecological Approach in Managing the Technology of Oil Refineries

“…To determine the probability of random events, failure (failures) and their consequences, three methods can be distinguished: Multiplicative, contingent valuation method of failure-free operation and the objective function method (Belskaya et al, 2014;Nusz et al, 2018).…”

Analysis of Volatile Methylsiloxanes in Water using a Small-scale Liquid-liquid Extraction Method followed by Gas Chromatography-mass Spectrometry (LLE-GC-MS)

“…WWTPs effluents are usually discharged to a surface water body (aquatic ecosystem), making them the main source of numerous contaminants to the environment, which can potentially cause risks to ecological receptors. This may result in the direct exposure of aquatic receptors and benthic invertebrates through the contact and/or ingestion of sediments, and indirect exposure through the aquatic food chain (Nusz et al 2018). Some studies have revealed that VMSs are potentially toxic to living organisms, since at high doses they affect the reproductive systems of animals, are carcinogenic, and harm the respiratory tract (Tran et al 2019).…”

Potenciais riscos associados à qualidade de sedimentos em zonas de prospecção mineral: Rio da Várzea, Rio Grande do Sul - Brasil

“…No passado, os sedimentos foram considerados um sumidouro para nutrientes e contaminantes ambientais, no entanto, atualmente, sabe-se que existe um equilíbrio dinâmico na interface sedimento/coluna de água que possibilita o intercâmbio de espécies químicas que podem apresentar riscos aos ecossistemas hídricos (HERATH et al, 2018;NUSZ et al, 2018;PJEMAN et al;. A avaliação do risco associado aos sedimentos de fundo pode ser definida como processos que caracterizam a probabilidade de que efeitos ecológicos adversos possam ocorrer sobre essa matriz ambiental ou estejam ocorrendo como resultado da exposição a um ou mais fatores de stress (CHAPMAN;HOLLERT, 2006;GERBERSDORF et al, 2015;PASCAUD et al, 2015).…”

“…Na busca por estratégias inovadoras na avaliação dos riscos associados à qualidade dos sedimentos, estudos recentes têm voltado sua atenção para investigações que associem linhas de evidência tradicionais (engenharia, física, química, ecotoxicologia e ecologia) com respostas oriundas de técnicas modernas de microbiologia e biologia molecular, abordagem de múltiplas linhas de evidência, ou quando associada a respostas de microbiologia e biologia molecular denominada 'Triad plus X' (BURTON;JOHNSTON, 2010;CHAPMAN, 2017;WIEPRECHT, 2015;NEDRICH et al, 2018;NUSZ et al, 2018).…”

“…Abordagens distintas vêm sendo empregadas por agências ambientais mundiais para o manejo e gestão de sedimentos contaminados, destacando-se os valores guias da qualidade dos sedimentos (VGQS), disponibilizando uma série de referências numéricas (BURTON, 2002(BURTON, , 2010MOZETO et al, 2006;NUSZ et al, 2018 (POMPÊO et al, 2013;USEPA, 2005;BURTON, 2002). Segundo essa abordagem, as bactérias oxidam a matéria orgânica presente nos sedimentos utilizando sulfatos como receptores de elétrons, gerando sulfeto de hidrogênico e compostos reduzidos de enxofre (BURTON, 2010;OMEE, 1993;SILVERIO et al 2006;USEPA, 2005).…”