The Impact of Leached Water from Plastic Bottles on Daphnia Magna

Overview

Plastic is now the most common container material for bottled water. Concerns have been raised that plastic may not be safe for storing water because the plastics or additives to the plastics are migrating into the water, particularly when heated. Here, we study the effects of water stored in plastic containers on the heart rate of Daphnia magna. D. magna is a model organism for toxicological studies because it is transparent and rapidly sensitive to substances in its fresh water environment. Two heating methods were used for water stored in 8 different containers: PETE, HDPE, Tritan (Nalgene), TPU, Polyurethane, Stainless steel, Glass, and disposable baby food containers. In both methods, non-heated controls were used in addition to the material controls of heated glass and stainless steel. In the first method, the containers were lined up along the rear south-facing window of a sedan in the sun with all windows closed for 8 hours on a hot summer day. In the second method, containers were placed in an incubator at 60℃ for 5 hours in the dark. Water samples from the containers were placed in glass tubes and adult D. magna were added. After 1 hour, their heart rates (HR) for the following hour were captured using slow motion video and an Olympus stereo microscope. For sedan-stored samples from PETE bottles, the HR were significantly below the control, while samples from HDPE and Nalgene bottles had significantly higher HR than the control. D. magna exposed to samples from a polyurethane container showed drastically reduced heart rates compared to the control. The HR of D. magna in water from the stainless steel bottle were significantly higher than the control. For these experiments, the least significant p-value was found to be 1.5x10-4. For samples from the incubator, the HR of D. magna exposed to water stored in HDPE containers were significantly higher than the control. A TPU container caused the daphnia’s heart rate to fall below the control. For these experiments the least significant p-value recorded was 5.3x10-3. These results suggest that, when a plastic bottle is left in a hot car, some sort of leaching occurs, since water from the plastic bottles had a greater impact on the heart rate of D. magna than water from the glass and stainless steel bottles. The results presented here also suggest that there is a difference between waters leached in the car and those leached in the controlled incubator environment, since waters stored in the incubator caused the daphnias’ heart rates to deviate less from the control than waters stored in the sedan.

Competition history

• AJAS 2019 Category not listed

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