Is drinking water from a plastic bottle that has been left out in the sun harmful?

Potential Harm from Drinking Water from Plastic Bottles Left in the Sun

Drinking water from plastic bottles left in the sun can be harmful due to the leaching of microplastics, chemicals, and heavy metals that may pose health risks including immune system effects, chemical toxicity, and potential carcinogenic risks.1

Health Concerns Associated with Sun-Exposed Plastic Bottles

Microplastic Contamination

• Microplastics (water-insoluble, solid polymer particles <5mm in size) have been detected in bottled water and can leach from plastic when exposed to heat and sunlight 2
• Although human health effects from microplastic exposure are still largely unknown, animal studies suggest microplastics may accumulate in the body and cause particle toxicity by inducing immune responses 2
• Microplastics can serve as carriers for other contaminants, as biofilms growing on microplastics may become sources of microbial pathogens 2

Chemical Leaching

• Heat from sun exposure significantly increases the leaching of chemicals from plastic bottles into the water 1, 3
• Styrene and other aromatic compounds (including ethyl benzene, toluene, and benzene) can leach from polystyrene bottles, with concentrations increasing with storage time 4
• Prolonged storage of bottled water (up to one year) can increase styrene concentration to 69.53 μg/L 4
• Plastic-associated chemicals (additives and adsorbed toxins) may cause chemical toxicity, though effects are likely dose-dependent 2

Heavy Metal Contamination

• Sun exposure of bottled water causes leaching of heavy metals including lead, arsenic, cadmium, chromium, and nickel in a duration-dependent manner 1
• After 42 days of sun exposure, bottled water can contain heavy metals exceeding WHO safety limits, with arsenic posing the highest non-carcinogenic risk and nickel posing the highest carcinogenic risk 1
• Antimony, a regulated contaminant with both acute and chronic health effects, leaches from PET (polyethylene terephthalate) bottles at rates that increase dramatically with temperature 5

Temperature Effects and Leaching Rates

• The rate of antimony release follows a power function model that accelerates with increasing temperature 5
• At temperatures of 60°C, 65°C, 70°C, 75°C, 80°C, and 85°C, antimony concentrations can exceed the EPA maximum contaminant level (6 ppb) after 176,38,12,4.7,2.3, and 1.3 days, respectively 5
• Summertime temperatures inside cars, garages, and enclosed storage areas can exceed 65°C in hot climates, promoting antimony leaching from PET bottled waters 5
• Hot water (100°C) can release millions of submicron and microparticles per mL from various plastic materials after just 60 minutes 3

Practical Implications

• The quality of plastic and storage time are major factors in chemical leaching 4, 1
• Temperature plays a critical role in accelerating the release of harmful substances from plastic bottles 3, 5
• Microbial parameters in sun-exposed bottled water often fail to meet WHO safety limits 1
• Paper cups have been found to be safer alternatives for hot drinks compared to plastic or styrofoam cups 4

Risk Assessment

• While most studies show that short-term exposure to bottled water under normal conditions results in contaminant levels below regulatory limits, prolonged sun exposure significantly increases health risks 1, 5
• Health risk evaluations reveal possible toxicity from chromium, cadmium, lead, arsenic, and nickel in sun-exposed bottled water 1
• Carcinogenic risk assessment indicates potential cancer risk from chromium, arsenic, and nickel exposure through drinking water from sun-exposed plastic bottles 1