Abstract:
Plastic bottles are commonly used for storing drinking water. However, limited knowledge
exists regarding the migration of chemicals from plastic into water. In Sri Lanka,
children often use reusable polypropylene (PP) plastic bottles for keeping water they
use throughout the day. This study aimed to investigate the migration of chemicals and
microplastic particles (MPs) into water stored for 24 hours in new PP plastic bottles
and, to determine the effect of temperature on this migration. We tested 24 one-liter PP
plastic bottles keeping distilled water and citric acid solutions at temperatures of 10◦C,
27◦C, 50◦C, and 80◦C after washing them with distilled water at 40◦C. Experiments were
conducted in triplicate, and all samples, including three bottle-washed water, were tested
for pH and filtered using membrane filter papers (0.2 μm pore size). MPs were captured
upon Nile red staining and fluorescent images, and MPs in all filtered samples were
counted using an orange lens under UV light (420-470 nm BLUE GG495: ORANGE)
with a stereo microscope. Results revealed that MPs in the range of 1-100 μm were
present in both solutions at all temperatures. The number of MPs migrating to drinking
water was increased with temperature (p < 0.05). We observed a decline of water pH in
all stored distilled water bottles under different temperatures. PP bottle-washed water
samples showed a significant pH difference, but no apparently significant pH difference
in citric acid samples. After 10 weeks, tap water stored in PP bottles showed decrease in
pH and increase in electrical conductivity (EC) along with temperature. These results
suggest that PP bottles storing different drinkables enhance the leaching of plasticrelated
compounds. Further the findings opens the needs of further research to identify
potential unknown chemical migrations supported by pH and EC changes, as well as
toxicological assessing of the relevance and risk of the MPs and other leachable identified.
