Drinking from a bottle left in a hot car

What does the evidence say about water bottles left in a hot car during pregnancy?

1. Peer-reviewed testing of PET, the clear plastic most disposable water bottles are made from, has focused on antimony, a metal catalyst left over from manufacturing, and found that PET-bottled water averaged about 0.2 parts per billion of antimony at room temperature but reached 6 parts per billion, the EPA's drinking water limit, within about 12 days at 70°C and within about 7 days at 80°C. 1
2. In another PET bottle study, heating a sample to 50°C raised its antimony level from about 0.5 to 8.5 parts per billion within 24 hours, already above the EPA limit, while antimony release at a normal room-temperature storage stayed low even over longer periods. 2
3. At normal room temperature, antimony leaching from PET bottles stays low even with extended storage, so the leaching documented in these studies is specifically about sustained heat exposure, like a hot car or truck, not about drinking from a normal bottle of water. 2
4. A parked car's interior can climb more than 22°C above the outside temperature, with most of that rise happening in the first 30 minutes, so a 72°F day outside can mean a car interior above 104°F within an hour, and cracking the windows barely changes that. 3
5. BPA, the chemical most associated with pregnancy concerns about plastic, is used in polycarbonate plastics and the epoxy resin lining many food and drink cans, not in PET, the plastic most disposable and reusable water bottles are made from. 4

Is water bottles left in a hot car safe in each trimester?

• First trimester. There's nothing trimester-specific about heat exposure to a plastic bottle. The leaching depends on temperature and time, not on how far along you are.
• Second trimester. If you're already swapping habits, this is a good time to keep a stainless steel or glass bottle in your bag for the car rather than relying on a disposable one that might sit in the heat.
• Third trimester. Hot summer errands and hospital-bag packing both mean more time in a warm car. Grab a fresh bottle rather than the one that's been riding around since morning.