Occurrence of microplastics in three types of household cleaning products and their estimated emissions into the aquatic environment

Microplastics (MPs) in household cleaning products are a significant source of primary MPs. However, their presence in these products remain largely unknown. In this study, three types of common household cleaning products (laundry detergents, toilet bowl cleaners, and dishwashing detergents) were examined to assess the presence of MPs. The potential global emissions of MPs into aquatic environments resulting from the use of these products were estimated using statistics on global wastewater treatment plants (WWTPs) and household cleaning product markets. The average abundance of MPs in household cleaning products was 564.97 +/- 327.83 n center dot kg (-1), with toilet bowl cleaners having a significantly higher abundance than the other two products. The most commonly detected polymers in these products were polyamide (PA), silicone, polyurethane (PU), acrylate copolymer (ACR), polyethylene (PE), and polyethylene terephthalate (PET), while the size of the MPs ranged from 21.34 to 442.97 mu m, with 81.52 % being < 50 mu m and 87.32 % being fragment-shaped. The estimated annual MP emissions from these three types of household cleaning products were 3.88 x 1013 +/- 1.35 x 1013, with toilet bowl cleaners accounting for 56.44 % of the total emissions. MPs directly released without treatment in WWTPs (2.46 x 1013 n year 1) accounted for 63.40 % of the total emissions, highlighting the importance of increasing the treated rate of wastewater to reduce MP emissions. Sensitivity tests indicated that increasing the MP removal rates of secondary and tertiary WWTPs could also effectively reduce MP emissions. Moreover, gross and per capita MP emissions in 149 countries showed significant differences, which could be attributed to population, market size, demand for household cleaning products, and the level of MP removal among different countries. The findings of this study provide important insights into controlling MP contamination in household cleaning products.

Automated summary

This study examined the presence of microplastics (MPs) in household cleaning products and estimated their potential emissions into aquatic environments. The results showed that the abundance of MPs in household cleaning products was relatively high, with toilet bowl cleaners having the highest content. The most commonly detected polymers in these products were polyamide, silicone, polyurethane, etc., and the size of the MPs was mostly below 50 micrometers. Direct emissions of untreated MPs accounted for a significant proportion of the total emissions, highlighting the importance of increasing wastewater treatment rates to reduce MP emissions. Additionally, there were significant differences in MP emissions among countries, which could be attributed to population, market size, and level of MP removal. The findings of this study are important for controlling MP contamination in household cleaning products.