SETAC Europe Highlights - Bioaccumulation Science

SETAC Europe Highlights - Bioaccumulation Science

The Society of Environmental Toxicology and Chemistry (SETAC) Europe held its 33rd Annual Meeting in Dublin, Ireland. Smithers experts presented various topics, along with other conference participants, around the theme of “Data-Driven Environmental Decision-Making.”
In this summary of meeting highlights, Dr. Kalumbu Malekani, Chief Scientific Officer of the Smithers Environmental Risk Sciences Division, shares points from sessions focused on advances in bioaccumulation science.
New Approach Methods for bioaccumulation assessment
Representatives from the European Chemicals Agency (ECHA) gave a presentation on “Strengthened Role of New Approach Methods (NAMs) in bioaccumulation assessment under REACH.”
Efforts are being made to substitute animal vertebrate testing with NAMs that can provide faster and more efficient mechanistic information. NAMs consist of in vitro methods and in silico computational models that can be used to predict complex biological endpoints alone or in combination and have the potential to be faster and cost-effective, ultimately reducing animal use. There is also an opportunity to integrate alternative methods to in vivo bioconcentration factor (BCF) in bioaccumulation assessment. Usually, bioconcentration or bioaccumulation data is obtained from aquatic species under REACH Annex XIII requirements.
An alternative to using fish in the BCF study is Hyalella azteca, which presents the following advantages: 
  • Non-vertebrate study
  • Simple to culture, shorter generations
  • Laboratory culture is well established, and the test medium requires low volume
  • Good correlation with fish BCF – recently demonstrated in an OECD ring test
  • Draft OECD test guideline is currently under review
  • Hyalella has lower typical lipid content of 3% compared to 5% in fish  
Already deployed, the in vitro clearance assays OECD 319A and OECD 319B use isolated primary hepatocyte or liver S9 subcellular fractions from rainbow trout and are currently employed as supporting information in the weight of evidence approach.
It is promising that regulators are more willing to accept the use of validated NAMs results as alternatives or scientific relevant information in the weight of evidence evaluations. Combining in vivo and in vitro data would strengthen the ability to determine the potential for a chemical’s bioactivity.

Mammalian bioaccumulation science
ECHA initiated a working group with experts and published a mammalian elimination half-life database for benchmarking (2021) – the session focused on the tiered assessment:
Tier 1: Screening criteria
  • Log Kow, log Koa
Tier 2: Intermediate tier
  • Information on biotransformation
  • Possibly other alternative methods e.g., use of toxicokinetic data
Tier 3: Definitive assessment
  • In vivo testing
  • Use of other data for assessment: monitoring data 
Future developments include regulatory and technical requirements, such as reassessment and validation of proposed methods and trigger values using larger data sets. Further research needs include in vitro clearance assays with mammalian material (primary hepatocyte assay and liver S9 assay are promising, especially with pharmaceuticals) and the possibility of covering different species and taxa.

The scientific discussions and sharing of research results contributed to an existing body of knowledge that will continue to help risk assessors and managers evaluate the risk that chemicals pose to the environment and human health. Other topics at the conference covered a wide range of research and regulatory themes, including hot topics such as endocrine disruption, the impacts of microplastics, pollinator risk assessment, life cycle assessment, biodegradation and persistence of chemicals, and climate change and its effects on environmental micropollutants.

We look forward to the SETAC North America 44th Annual Meeting in Louisville, KY, in November, and the SETAC Europe 34th Annual Meeting in Seville, Spain, in 2024.

To discuss these themes and other research presented at the SETAC Europe meeting, reach out to Dr. Malekani, or contact our experts to learn more about the research Smithers is conducting in bioaccumulation testing.

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