An EU-funded study by researchers in Germany found that water fleas exposed to soluble polymers of the kinds commonly found in paints, cosmetics, and paper reproduced less frequently and generated less progeny. The findings come as the EU contemplates incorporating polymer registration in REACH, a move that could significantly expand the amount of hazard and exposure information on these compounds that is already available.

The possible dangers of water-soluble synthetic polymers are mostly unknown (WSSPs). WSSPs make up an estimated 6% of the worldwide polymer market, however, they are much less frequently discussed in the media than other polymeric pollutants like microplastics

Acute and chronic water flea (Daphnia) testing were performed by Simona Mondellini, a Ph.D. candidate at the University of Bayreuth, and colleagues for the following five WSSPs:

1. Polyvinyl alcohol (PVOH)
2. Polyvinyl pyrrolidone
3. Polyethylene oxide (PEO)
4. Polyethylene glycol (PEG) and
5. Polyacrylic acid (PAA) (PVP)

According to a study published in Science of the Total Environment, acute exposure up to 50 mg/L had no negative effects, but a 21-day chronic exposure test conducted following OECD test guideline 211 resulted in a variety of consequences at either 5 mg/L or 10 mg/L.

Fleas exposed to PAA, PEG, PVOH, or PVP reproduced less frequently and generated fewer young in the case of PEG or PVOH. Fleas exposed to PVOH and PVP also showed size-related effects, according to the researchers. For regulatory purposes, the water flea is regarded as a "model" species for assessing aquatic toxicity.

For example, in Annexes VII and IX of EU REACH, it is the preferred species for both short- and long-term toxicity assessment for invertebrates.

Current understanding:

More WSSPs than those linked to impacts in the current study have been discovered in the environment in Europe, according to at least one earlier investigation. PVP was discovered in an outflow from a German wastewater treatment facility in 2018 by Marketa Julinová, Ludmila Vaharová, and Martin Jura of Tomas Bata University in the Czech Republic at quantities up to 7.1mg/L.

Researchers at McGill University in Montreal, Canada, discovered PEG in recently fallen snow in their city in a 2021 investigation. This implies that some WSSPs are mobile in both air and water and may so spread farther.

The present study's researchers warn that the consequences could, over time, have a detrimental influence on water flea populations as well as the larger ecology.

Three anionic homo- and copolymers of acrylic acid and ten PEGs were determined to have little or no toxicity in a literature review last year that was supported by the German cosmetics industry. The substances, chosen for testing due to their high relevance to cosmetics, led the researchers to draw the provisional conclusion that they were likely to pose a little environmental risk. However, they noted that this was only a provisional conclusion and that additional ecotoxicity data was still needed, among other reasons.

References: https://www.sciencedirect.com/science/article/pii/S0048969722047064?via%3Dihub