In my post from February 5, 2011, I discussed a study that revealed detectable levels of BPA in humans. You may be wondering; however, how people know whether BPA actually leaches from plastic. Scientists use a variety of instrumental analyses to find the answers to such questions. That is they use instruments that are specifically designed to determine concentrations of a particular substance.
My Experience with Instrumental Analysis
Last semester I took an Instrumental Analysis class at the university that gave me first hand experience with the matter. The class involved writing standard operating procedures for spectroscopy instruments as well as developing and carrying out an experiment using one of the instruments. Spectroscopy instruments are used to detect the individual chemical components in a sample. Because of these instruments, levels of chlorine and lead can be detected in water. They are also used by detectives and crime scene investigators in analyzing evidence. The instrument I worked with was a Gas Chromatography-Mass Spectrometer which is the same instrument many scientists use to detect BPA. My experiment involved detecting benzene levels in gasoline samples from various gas stations. The gas samples had to be stored in glass containers and could not be in contact with plastic of any sort. Plastic could not come into contact with the samples because BPA and phthalates from the plastic would leach into the sample and interfere with the benzene analysis.
Any scientist with knowledge about spectroscopy instruments will tell you that samples should never come in contact with plastic because of leaching.
Several experiments have been conducted using Gas Chromatography-Mass Spectrometry (GCMS) to study the leaching of BPA from plastic.
One article in the
Food Additives and Contaminants journal titled, "Migration of bisphenol A from plastic baby bottles, baby bottle liners and reusable polycarbonate drinking bottles" by C. Kubwabo et al discusses results of a BPA leaching test performed with GCMS.
Specifics of the Study
This experiment was carried out to simulate effects of repeated use and washing of baby bottles. A variety of temperatures and exposure times were also used.
Results of the Study
The study concludes that the amount of BPA that leaches from plastic can vary depending on time and temperature. BPA leaches into food/drink at higher concentrations with increased temperature and time. At higher temperatures, chemical reactions speed up allowing for increased interaction of BPA and food. Therefore, it is not a good idea to heat plastics or to store heated food/drink in plastic containers.
Results of the study conclude that containers made out of polycarbonate (PC) leached a BPA concentration range of 0.11 micrograms/liter to 2.39 micrograms/liter. Leaching at the higher levels occurred in foods high in alcohol and fat (baby formula was considered a fatty food for this study). Non-PC container samples only contained barely traceable amounts of BPA. The study concludes that 1) BPA leaches from PC containers and 2) non-PC and glass containers are safer for use than PC containers.
Sources:
Kubwabo, C., I. Kosarac, B. Stewart, K. Lalonde, and P.J. Lalonde. "Migration of Bisphenol A from Plastic Baby Bottles, Baby Bottle Liners and Reusable Polycarbonate Drinking Bottles." Food Additives and Contaminants 26.6 (2009): 928-37. Scifinder. Web. Mar. 2011.
I used this source because it was published in a scientific journal and reviewed by the scientific community. It uses controls and accepted scientific practices. The data/results for this study are also comparable to similar studies done on BPA. Therefore, it is a highly reliable source.
Polystyrene (PS) 
