To determine if using plastic bottle/ bag for hot takeaway food will lead to the leakage of phthalates
Fareez Keegan (S10130310H), Tuieng Wei Ting (S10131147G)
2FO3/ PO1
29/07/2013
Case Study
It has long been known that minute amount of plastic get into our food from containers through the process called "leaching" or "migration." But what could possibly be harmful? Discussions about the safety of plastics used to package food have spurred the studies on the adverse health effects they have on humans. Two prime suspects of the leached plastics are under active investigation: bisphenol A and a class of chemicals called phthalates.
Heating food in plastic seems to increase the amount that has transferred to food. Migration also increases when plastic touches fatty, salty, or acidic foods. In this research, we will be investigating the amount of phthalates (specifically nine) in 72 individual food samples purchased in Albany, New York.
Introduction
Phthalates are man-made chemicals used in soft, flexible plastics, polyvinyl chloride (PVC) products, and in a variety of personal care products (shampoos, lotions, etc.). People may be exposed to phthalates through ingestion, inhalation, absorption through the skin, or parenteral administration (which occurs with the use of some medical devices)
The 9 phthalates mentioned in the research paper and their metabolites are:
Note: High Molecular Weight (HMW) phthalates are slightly soluble in water
Low Molecular Weight (LMW) phthalates are reasonably soluble in water
Health risks:
- Early onset of puberty
- Interfering with the male reproductive tract development
- Interfering with the natural functioning of the hormone system
- Causing reproductive and genital defects
- Lower testosterone levels in adolescent males
- Lower sperm count in adult males
Phthalates are weak endocrine disruptors and androgen blocking chemicals. This means that when absorbed into the body phthalates can either mimic or block female hormones, or in males, suppress the hormones involved in male sexual development.
Analytical Methods available:
- Liquid Chromatography
- Gas Chromatography
- High Performance Liquid Chromatography
Selected Analytical Method to be used
- Gas Chromatography coupled with Mass Selective detector and Selective Ion monitoring
Advantages of GC over HPLC:
- Better chromatographic resolution of single compounds
- Common use of mass selective detectors in GC
Advantages of MS detector over all other detectors (FID, ECD, FT-IR):
- More sensitive
- Specific (to find the right peaks in noisy background which is normal in samples of organically rich matrices)
After chromatographic separation either by GC or LC, mass specific detection in conjunction with selective ion monitoring will be used for the detection of phthalates.
As all phthalates except DMP form the ion with m/e 149, the esters are easy to identify. With the exception of barbiturates and cholesterol derivatives almost no other compounds exhibit this fragment ion (Furtmann 1993).
However the method only permits a general identification as phthalate. Further information can only be obtained from the retention time. Hence, a suitable detector is needed for the most accurate results.
According to Berset and Etter-Holzer (2001), EI-MS was the most sensitive detection technique. Other ionisation method is positive chemical ionisation (PCI) and negative chemical ionisation (NCI).
Materials & Methods
Analysis of a sample of commonly consumed foods (in New York) using gas chromatography–mass spectroscopy. The product of the food consumption rate and concentration of phthalates in the food samples will give us the estimated value of dietary intakes of phthalates.
Procedure:
(I) Preparation of samples
All glassware was baked at 450°C overnight.
1. Freeze-dry all food samples (1.5–20 g), except soft drinks using a freeze drier (Labconco, Kansas City, MO),
2. Grind to a fine powder using a precleaned mortar and pestle
3. Spike with 50 ng deuterated internal standards [D4-DMP, D4-DEP, D4-DnHP (for BBzP), D4-DCHP, D4-DBP, D4-DiBP, D4-DEHP and D4-DnOP] (AccuStandard Inc., New Haven, CT)
For liquid samples that do not contain lipids,
1. Extract 50 g samples three times with 15 mL hexane by shaking for 30 min
2. Concentrate the combined extracts to 2 mL using a rotary evaporator
For solid foods,
1. Extract the ground samples with 20 mL acetone:hexane (1:1, vol:vol) three times
2. Centrifuge after shaking for 30 min
3. Combine upper organic layers
4. Concentrated to 1 mL and transfer to 35 mL glass tubes with PTFE (Teflon) caps
5. Add 30 mL hexane–saturated acetonitrile solution and 3 mL hexane
6. Shake samples for 10 min and discard the upper layer (repeat three times)
For cookies, which contain large amounts of lipids, after three extractions,
1. Place extracts in a refrigerator for half an hour
2. Transfer upper layer into another tube for further concentration
3. Concentrate the extracts to near dryness
4. Add 2 mL hexane for further clean up by column chromatography
(II) Preparation of solvents
1. Purification of extracts using a glass column packed with 7 g Florisil 60–100 mesh (Aldrich, St. Louis, MO)
2. Phthalates were eluted with 70 mL acetone:hexane (2:8, vol:vol).
3. The final eluate was concentrated to 0.5 mL under a gentle stream of nitrogen for gas chromatography–mass spectrometry (GC-MS) analysis.
4. For each batch of 10 samples, 3 method blanks—a spiked blank and a pair of matrix-spiked samples (spiked with 100 ng each of target phthalates) per duplicate—were processed.
Validation of methods
If the difference in concentrations among the blanks exceeded 50 ng, a when the concentrations of DEHP and DBP in the 3 procedural blanks varied widely, then all the data were discarded, and samples were reanalyzed. Mean blank values were subtracted from sample values for each batch.
Internal standard method is also used to minimize error during manual injection. Extractions of phthalates from the food samples are done more than once to ensure enough phthalates are extracted for GC-MS analysis.
Internal standard method is also used to minimize error during manual injection. Extractions of phthalates from the food samples are done more than once to ensure enough phthalates are extracted for GC-MS analysis.
(III) Instrumental Conditions
- Gas chromatograph (Agilent Technologies 6890N)
- Mass spectrometer (Agilent Technologies 5973)
- Selective ion monitoring mode
- fused-silica capillary column (DB-5; 30 m × 0.25 mm i.d.; 0.25 mm film thickness)
- Splitless mode
- Temperature of injector: 280°C
- Temperature of ion source: 230°C
- Programmed temperature mode
- 80°C (held for 1.0 min)
- 180°C at 12°C/min (held for 1.0 min)
- 230°C at 6°C/min
- 270°C at 8°C/min (held for 2.0 min)
- 300°C at 30°C/min (held for 12 min)
Quantification is done by using deuterated internal standards for each phthalate.
Risk Assessment
Analytical Results
Table 1 shows the consumption rates of each food group, in units of grams per kilogram per day along with the individual food products constituting each food group and the container types for the individual food samples.
Of the food groups evaluated for adults, condiments had the lowest estimated consumption rate (0.2 g/kg/day) and beverages had the highest (13 g/kg/day). The estimated consumption rate for infant foods was 56 g/kg/day.
At least some phthalates is detected in every food group in this study. DEHP was detected in 74% of food samples, including all seven infant food samples, whereas DCHP was detected in only 6% of food samples (Table 2).
Discussion & Conclusion
According to the results shown above, traces level of phthalates are found in all of the food samples. Even without heating there is leaching of phthalates into the food. The bonds in phthalates being susceptible to high heat will be altered to form the phthalate esters, resulting in leaching. Though the plastic containers may have the microwave-safe logo, there is no 100% confirmation that there will not be leaching of phthalates. Future studies will be needed to concentrate on the influence of different types of packaging and the preparation of food. It is also better to take precaution when using plastic to package food or purchasing processed food packaged in plastic.
However it is important to note that this analysis is only done on food samples from one area. Hence, it does not necessarily portray the same results for other packaged food from other areas and countries.
References
Heise, S., Litz, N. (2004) Deskstudy PHTHALATES, [ONLINE],
[Accessed: 28 July 2013]
Schecter, A., Lorber, M., Guo, Y., Wu, Q., Se H.Y., Kannan, K., Hommel, M., Imran, N., Hynan, L.S., Cheng, D., Colacino, J.A., Birnbaum, L.S. (2013) Phthalate Concentrations and Dietary Exposure from Food Purchased in New York State, [ONLINE],
Available: http://ehp.niehs.nih.gov/1206367/
[Accessed: 28 July 2013]
Schardt, D. (2005) Microwave Myths, [ONLINE],
[Accessed: 28 July 2013]
Food and Environmental Hygiene Department, The Government of the Hong Kong Special Administrative Region. (2005) Microwave Cooking and Food Safety, [ONLINE],
[Accessed: 28 July 2013]
Hoffman, M. (2008) Pots, Pans and Plastics: A Shopper’s Guide to Food Safety, [ONLINE]
[Accessed: 28 July 2013]
The National Academy of Sciences. (2008) Phthalates and Cumulative Risk Assessment The Tasks Ahead, [ONLINE]
[Accessed: 28 July 2013]
Zero breast cancer. (n.d) Phthalates The Everywhere Chemical, [ONLINE]
[Accessed: 28 July 2013]
No comments:
Post a Comment