# Reality Check: Experimental Studies on Microplastics Lack Realism
## 6 Leached Chemicals
### Aquatic Effects
In a study of early life stages, marine medaka _Oryza melastigma_ embryos and larvae were exposed to suspended MPs spiked with benzo(a)pyrene (MP-BaP), perfluorooctanesulfonic acid (MP-PFOS), or benzophenone-3 (MP-BP3) for 12 days [83]. The MPs agglomerated on the surface of the egg chorion (outer membrane) but did not penetrate it. While embryos exposed to virgin MPs showed no effects, those exposed to MPs with PFOS had decreased survival and did not hatch. Larvae exposed to MPs spiked with BaP or with BP3 showed developmental anomalies, reduced growth, and abnormal behavior. Thus, compared to similar water concentrations, BaP and PFOS spiked on MPs appeared to be more embryotoxic. These data suggest pollutant transfer by contact of MPs on the chorion of fish embryos. An effect of particle size was also seen, with smaller particles having more severe effects than larger ones. [PERSON] et al. (2021) exposed larval fathead minnows to pre-consumer MPs and environmental MPs and found environmental MPs caused a more drastic increase in length and weight and almost six times more deformities as the pre-consumer MPs [84]. Effects of low-density polyethylene (LDPE) MPs (11-13 um), with and without adsorbed contaminants (benzo[a]pyrene--BaP and perfluorooctane sulfonic acid--PFOS), were studied on the clam, _Scrobicularia plana_[85]. Environmentally relevant concentrations of contaminants were adsorbed onto MPs to evaluate their potential role as a vector for toxic chemicals after ingestion. _S. plana_ were exposed at 1 mg L\({}^{-1}\) for fourteen days and were sampled after three, seven, and fourteen days. BaP accumulation in tissues, enzymatic biomarkers, genotoxicity in the gills, digestive gland, and hemolymph, and neurotoxicity were evaluated. Results suggested that physical injury of gills by MPs could affect the biomarkers. The digestive gland was less affected by physical damage from virgin MPs than by MPs with adsorbed chemicals, indicating desorption and toxic effects on the biomarkers measured. A 21 day exposure of the fish _Sparus aurata_ juveniles to virgin and weathered MPs was performed [86]. Fish were analyzed for a suite of enzyme biomarkers and behavioral changes, specifically social interactions and feeding behavior. Results indicated cellular stress from virgin MPs, and greater stress from weathered MPs. Behavioral effects indicated that fish exposed to either type of MPs were significantly bolder during social interactions than controls. The toxicity of leachates from beached MPs and virgin industrial MPs (PVC) to sea urchin embryos (_Paracentrotus lividus_) was investigated [87]. The weathered beached MPs, which contained polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), produced severe, consistent, and specific developmental abnormalities in embryos and larvae. However, embryos exposed to virgin MP leachates without additives or environmental contaminants showed normal development, suggesting that the abnormalities observed from beached MPs are the result of exposure to either adsorbed contaminants or industrial additives. Unlike other types of MPs, MFs from textiles have unique dyes and chemicals such as surface treatments, anti-microbials, brominated flame retardants that are used in the production of textiles, and which have been shown to be highly toxic [64, 65, 88]. Furthermore, chemical additives were detected in aqueous leachates of virgin and aged (photodegraded) MFs [89]. These have been greatly understudied.