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Chemistry science fair project:
Determination of Bisphenol A in Thermal Paper and Receipts




Science Fair Project Information
Title: Determination of Bisphenol A in Thermal Paper and Receipts in the Ottawa Region
Subject: Food Science
Grade level: Middle School - Grades 7-9
Academic Level: Ordinary
Project Type: Experimental
Cost: Medium
Awards: 1st place, Canada Wide Virtual Science Fair ($300)
Affiliation: Canada Wide Virtual Science Fair (VSF)
Year: 2011
Equipment, Materials and Techniques: nitrogen pump and evaporator, ultrasonic bath, fume hood, electronic balance, gas chromatographer / mass spectrometer
Description: Chemical compounds extracted from receipts were derivatized by Trimethylsilyl. The derivatives were then analyzed by Gas Chromatography / Mass Spectrometry for Bisphenol A. The same procedure could be adapted for foods and other consumer products analysis.
Link: http://www.virtualsciencefair.org/2011/chenj2
Short Background

Bisphenol A in Thermal Paper and Receipts

BPA is controversial because it exerts weak, but detectable, hormone-like properties, raising concerns about its presence in consumer products and foods contained in such products. Starting in 2008, several governments questioned its safety, prompting some retailers to withdraw polycarbonate products. A 2010 report from the United States Food and Drug Administration (FDA) raised further concerns regarding exposure of fetuses, infants, and young children. In September 2010, Canada became the first country to declare BPA a toxic substance. In the European Union and Canada, BPA use is banned in baby bottles.

Bisphenol A is a weak endocrine disruptor, which can mimic estrogen and may lead to negative health effects. Early developmental stages appear to be the period of greatest sensitivity to its effects, and some studies have linked prenatal exposure to later neurological difficulties. Regulatory bodies have determined safety levels for humans, but those safety levels are currently being questioned or are under review as a result of new scientific studies. A 2011 study that investigated the number of chemicals pregnant women are exposed to in the U.S. found BPA in 96% of women.

The major human exposure route to BPA is diet, including ingestion of contaminated food and water. There is limited evidence on inhalation exposure and the body of research on dermal absorption continues to grow.

Bisphenol A has been known to be leached from the plastic lining of canned foods and polycarbonate plastics, especially those cleaned with harsh detergents or that contain acidic or high-temperature liquids. BPA is an ingredient in the internal coating of metal food and beverage cans used to protect the food from direct contact with the can. A recent Health Canada study found that the majority of canned soft drinks it tested had low, but measurable levels of bisphenol A. Furthermore, a study conducted by the University of Texas School of Public Health in 2010, found BPA in 63 of 105 samples of fresh and canned foods, foods sold in plastic packaging, and in cat and dog foods in cans and plastic packaging. This included fresh turkey, canned green beans, and canned infant formula. While most human exposure is through diet, exposure can also occur through air and through skin absorption.

Free BPA is found in high concentration in thermal paper and carbonless copy paper, which would be expected to be more available for exposure than BPA bound into resin or plastic. Popular uses of thermal paper include receipts, event and cinema tickets, labels, and airline tickets. A Swiss study found that 11 of 13 thermal printing papers contained 8 – 17 g/kg Bisphenol A (BPA). Upon dry finger contact with a thermal paper receipt, roughly 1 μg BPA (0.2 – 6 μg) was transferred to the forefinger and the middle finger. For wet or greasy fingers approximately 10 times more was transferred. Extraction of BPA from the fingers was possible up to 2 hours after exposure. Further, it has been demonstrated that thermal receipts placed in contact with paper currency in a wallet for 24 hours cause a dramatic increase in the concentration of BPA in paper currency, making paper money a secondary source of exposure. Also, other paper products, such as toilet paper, newspapers and napkins, become contaminated with BPA during the recycling process. Free BPA can readily be transferred to skin, and residues on hands can be ingested. Bodily intake through dermal absorption (99% of which comes from handling receipts) has been shown for the general population to be 0.219 ng/kg bw/day (occupationally exposed persons absorb higher amounts at 16.3 ng/kg bw/day) whereas aggregate intake (food/beverage/environment) for adults is estimated at 0.36–0.43 μg/kg bw/day (estimated intake for occupationally exposed adults is 0.043–100 μg/kg bw/day).

Children may be more susceptible to BPA exposure than adults. A recent study found higher urinary concentrations in young children than in adults under typical exposure scenarios. In adults, BPA is eliminated from the body through a detoxification process in the liver. In infants and children, this pathway is not fully developed so they have a decreased ability to clear BPA from their systems. It is also estimated that from food consumption, infants and young children have higher BPA-exposure than adults.

See also: http://en.wikipedia.org/wiki/Bisphenol_A

Source: Wikipedia (All text is available under the terms of the GNU Free Documentation License and Creative Commons Attribution-ShareAlike License.)

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