Are current regulatory log K cut-off values fit-for-purpose as a screening tool for bioaccumulation potential in aquatic organisms?

Persistent, Bioaccumulative and Toxic (PBT) and very Persistent and very Bioaccumulative (vPvB) are regulatory hazard categories that have been set to manage the possible risks to humans and the environment from these chemicals. In industrial chemicals regulations, their aquatic Bioaccumulation potential is usually assessed first with a screening based on the octanol/water partition coefficient (K). However, current log K cut-off values triggering classification, categorisation and/or further fish bioconcentration testing are not harmonised worldwide, and they have never been assessed for their regulatory relevance.

Investigations On the Fish Acute Toxicity of Fragrance Ingredients Involving Chinese Fish Species and Zebrafish Embryos.

While zebrafish (Danio rerio) have been accepted worldwide for evaluating chemical hazards to aquatic vertebrates, and in some countries it is mandated to generate fish toxicity data using native species, such as Chinese rare minnow (Gobiocypris rarus) in China. This represents an additional regulatory constraint that may cause redundant tests, additional animal uses, and higher costs. Previous studies showed that juvenile G.

Species and Life-Stage Sensitivity of Chinese Rare Minnow (Gobiocypris rarus) to Chemical Exposure: A Critical Review.

Chemical production and consumption in Asia are increasing at an unprecedented rate, calling for regulations on chemical management. Under the New Chemical Substance Notification in China, information on ecotoxicological effects of chemicals is mandatory for the simplified registration of chemicals with the requirement that one ecotoxicological test is conducted locally. It is now mandatory to use the native fish species Chinese rare minnow (Gobiocypris rarus).

Country-Specific Environmental Risks of Fragrance Encapsulates Used in Laundry Care Products.

Fragrance encapsulates (FEs) are designed to deliver fragrance components, notably in laundry care products. They are made of thermoset polymeric shells surrounding the fragrance content. These materials enter the environment mainly during laundry washing, but little is known about their distribution in and impact on the environment.

In Vitro Biotransformation Assays Using Liver S9 Fractions and Hepatocytes from Rainbow Trout (Oncorhynchus mykiss): Overcoming Challenges with Difficult to Test Fragrance Chemicals.

In vitro metabolic stability assays using rainbow trout (Oncorhynchus mykiss) isolated hepatocytes (RT-HEP) or hepatic S9 fractions (RT-S9) were introduced to provide biotransformation rate data for the assessment of chemical bioaccumulation in fish. The present study explored the suitability of the RT-HEP and RT-S9 assays for difficult test chemicals, and the in vitro-based predictions were compared to in silico-based predictions and in vivo-measured bioconcentration factors (BCFs). The results show that volatile or reactive chemicals can be tested with minor modifications of the in vitro protocols.

A streamlined workflow to study direct photodegradation kinetic and transformation products for persistence assessment of a fragrance ingredient in natural waters.

Photodegradation can be an important abiotic degradation process to consider for the fate and persistence assessment of chemical substances in the environment. In this work, using a fragrance ingredient (FI, (E)-4-(2,2,3,6-tetramethylcyclohexyl)but-3-en-2-one) as an example, we developed a streamlined workflow to investigate direct photodegradation of chemicals in the aquatic environment, including laboratory investigation of kinetics and transformation products and estimation of its aquatic environmental half-lives. Direct photodegradation was determined to be the dominant photodegradation process for FI with a quantum yield of 0.

Intestinal Fish Cell Barrier Model to Assess Transfer of Organic Chemicals in Vitro: An Experimental and Computational Study.

We studied the role of the fish intestine as a barrier for organic chemicals using the epithelial barrier model built on the rainbow trout () intestinal cell line, RTgutGC and the newly developed exposure chamber, TransFEr, specifically designed to work with hydrophobic and volatile chemicals. Testing 11 chemicals with a range of physicochemical properties (logK: 2.2 to 6.

Extending the concept of predicting fish acute toxicity in vitro to the intestinal cell line RTgutGC.

Testing chemicals for fish acute toxicity is a legal requirement in many countries as part of environmental risk assessment. To reduce the numbers of fish used, substantial efforts have been focussed on alternative approaches. Prominently, the cell viability assay with the rainbow trout (Oncorhynchus mykiss) gill cell line, RTgill-W1, has been recognized, owing to its high predictive power and robustness.

Animal use replacement, reduction, and refinement: development of an integrated testing strategy for bioconcentration of chemicals in fish.

When addressing the use of fish for the environmental safety of chemicals and effluents, there are many opportunities for applying the principles of the 3Rs: Reduce, Refine, and Replace. The current environmental regulatory testing strategy for bioconcentration and secondary poisoning has been reviewed, and alternative approaches that provide useful information are described. Several approaches can be used to reduce the number of fish used in the Organization for Economic Cooperation and Development (OECD) Test Guideline 305, including alternative in vivo test methods such as the dietary accumulation test and the static exposure approach.

Vitellogenin: a review of analytical methods to detect (anti) estrogenic activity in fish.

Vitellogenin, the fish egg yolk precursor protein, is the most common biochemical endpoint in general use for the detection of (anti) estrogen active substances in fish and other oviparous species. This review aims to cover the major methods (both protein and nucleic acid) for vitellogenin determination. Comparisons are drawn between vitellogenin and other endpoint effect levels.