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Filters: Author is Stephen B. Weisberg  [Clear All Filters]
2022
Hampton, L. M. Thornto; Bouwmeester, H.; Brander, S. M.; Coffin, S.; Cole, M.; Hermabessiere, L.; Mehinto, A. C.; Miller, E.; Rochman, C. M.; Weisberg, S. B. 2022. Research recommendations to better understand the potential health impacts of microplastics to humans and aquatic ecosystems. Microplastics and Nanoplastics 2 (18).

To assess the potential risk of microplastic exposure to humans and aquatic ecosystems, reliable toxicity data is needed. This includes a more complete foundational understanding of microplastic toxicity and better characterization of the hazards they may present. To expand this understanding, an international group of experts was convened in 2020–2021 to identify critical thresholds at which microplastics found in drinking and ambient waters present a health risk to humans and aquatic organisms. However, their findings were limited by notable data gaps in the literature. Here, we identify those shortcomings and describe four categories of research recommendations needed to address them: 1) adequate particle characterization and selection for toxicity testing; 2) appropriate experimental study designs that allow for the derivation of dose-response curves; 3) establishment of adverse outcome pathways for microplastics; and 4) a clearer understanding of microplastic exposure, particularly for human health. By addressing these four data gaps, researchers will gain a better understanding of the key drivers of microplastic toxicity and the concentrations at which adverse effects may occur, allowing a better understanding of the potential risk that microplastics exposure might pose to human and aquatic ecosystems.

 (466.11 KB)
Mehinto, A. C.; Wagner, M.; Hampton, L. M. Thornto; Burton, Jr, A. G.; Miller, E.; Gouin, T.; Weisberg, S. B.; Rochman, C. M. 2022. Risk-based management framework for microplastics in aquatic ecosystems. Microplastics and Nanoplastics 2 (17).

Microplastic particles (MPs) are ubiquitous across a wide range of aquatic habitats but determining an appropriate level of risk management is hindered by a poor understanding of environmental risk. Here, we introduce a risk management framework for aquatic ecosystems that identifies four critical management thresholds, ranging from low regulatory concern to the highest level of concern where pollution control measures could be introduced to mitigate environmental emissions. The four thresholds were derived using a species sensitivity distribution (SSD) approach and the best available data from the peer-reviewed literature. This included a total of 290 data points extracted from 21 peer-reviewed microplastic toxicity studies meeting a minimal set of pre-defined quality criteria. The meta-analysis resulted in the development of critical thresholds for two effects mechanisms: food dilution with thresholds ranging from ~ 0.5 to 35 particles/L, and tissue translocation with thresholds ranging from ~ 60 to 4100 particles/L. This project was completed within an expert working group, which assigned high confidence to the management framework and associated analytical approach for developing thresholds, and very low to high confidence in the numerical thresholds. Consequently, several research recommendations are presented, which would strengthen confidence in quantifying threshold values for use in risk assessment and management. These recommendations include a need for high quality toxicity tests, and for an improved understanding of the mechanisms of action to better establish links to ecologically relevant adverse effects.

 (1.3 MB)
2021
Moore, S.; Hale, T.; Weisberg, S. B.; Flores, L.; Kauhanen, P. 2021. California Trash Monitoring Methods and Assessments Playbook. SFEI Contribution No. 1025. San Francisco Estuary Institute: Richmond, Calif.

As municipalities and water-quality regulatory agencies have implemented programs and policies to improve management of the trash loading to storm drain conveyances, there has been increased interest in using a common set of methods to quantify the effectiveness of management actions. To create a foundation for developing a consistent, standardized approach to trash monitoring statewide, the project team performed a method comparison analysis, based on two seasons of fieldwork. This analysis facilitated the assessment of the accuracy, repeatability, and efficiency of some already developed trash monitoring methodologies already in use, as well as help to investigate a new, innovative method (cf. Fielding Testing Report on trashmonitoring.org). Methods developed by the Bay Area Stormwater Management Agencies Association (BASMAA) for use in the San Francisco Bay Area were compared to methods developed by the Southern California Stormwater Monitoring Coalition (SMC) for use in coastal southern California. One of the chief goals of these comparisons was to understand the similarities and differences between the already existing methods for detecting, quantifying, and characterizing trash in selected environments. Readers will find that the data bear out remarkable levels of accuracy and precision with quantitative metrics that help to align methods and management concerns. Furthermore, the degree of correlation among tested methods were especially high, offering greater opportunities for inter-method comparisons.


The findings of this project are intended for use by public agencies, non-profit organizations, private consultants, and all of their various partners in informing a statewide effort to adopt rigorous, standardized monitoring methods to support the State Water Board’s Trash Amendments. Over the next couple of decades, such public mandates will require all water bodies in California to achieve water quality objectives for trash.

 (299.99 MB)
Moore, S.; Hale, T.; Weisberg, S. B.; Flores, L.; Kauhanen, P. 2021. Field Testing Report: California Trash Monitoring Methods. SFEI Contribution No. 1026. San Francisco Estuary Institute: Richmond, Calif.

Trash has received renewed focus in recent years as policy makers, public agencies, environmental organizations, and community groups have taken many steps towards trash quantification and management across California. The range of management actions is matched by the diversity of monitoring approaches, designed to determine key attributes associated with trash pollution on California’s lands and in its waterways.

This report describes the field testing associated with a project designed to validate the accuracy, precision, and practicality of several trash monitoring methods, practiced across the state. Additionally, the project measured the efficacy of a novel monitoring method designed to detect trash via remote sensing and machine learning. Readers will find details about each respective method -- the specific approach to
landscape characterization, the qualitative or quantitative measures undertaken, the team-based quality assurance for data collection -- as well as the approach that the testing team adopted to ensure efficient, accurate, and useful validation of the methods.

Because the validation efforts integrated multiple methods, using multiple teams at a selection of common sites, the field testing report yields useful statistical information not only about each method individually, but about the comparability of the results. The report illustrates the
correlation factor associated with different forms of trash metrics, associated with different methods practiced on the same assessment sites. The results illustrated a generally high degree of correlation among different methods, which promises opportunities to compare results meaningfully across methods.

Furthermore, this field testing report provides quantitative measures to illustrate the repeatability of each method, the differences and insights yielded by assessment site sizing criteria varying among methods, the transferability / teach-ability of each method among trash monitoring practitioners, and how the degrees of accuracy might aid programs in performing mass balance analysis of known sources
to trash detected in a given site.

Regarding innovation, the project team leveraged multiple on-the-ground methods and special testing scenarios to compare conventional and novel (aerial) assessments to measure the relative accuracy and precision of this emergent technology that might address some of the resource constraints that currently limit the broader or more frequent deployment of conventional trash assessment methods. The analyses captured in this field testing report offer specific quantitative measures of the accuracy (bias), precision (repeatability), practicality and cost associated with each method. This information is subsequently used to inform a companion summary analysis found in the Trash Monitoring Playbook, which is designed to evaluate the applicability of the monitoring methods to address classes of
monitoring questions.

 (14.46 MB)