Research on endocrine disrupting chemical and estrogenic activity status in bottled water – Dr Natalie Aneck Hahn
Dr Natalie Aneck Hahn
- Department of Urology, School of Medicine, Faculty of Health Sciences, University of Pretoria
- Biography of Dr Aneck-Hahn
The endocrine disrupting chemical and estrogenic activity status in bottled water.
Bottled mineral water consumption is steadily rising in the world as an alternative to tap water. The mineral water and soft drinks are often packaged in plastic bottles where they may be stored for several months at varying temperatures. It is well known that water may be contaminated with the components of plastic containers by a diffusion process. Some of these components have endocrine disrupting properties with the potential to have negative effects on the endocrine systems of humans and wildlife. Many EDCs are also associated with the development of various cancers such as testicular, prostate and breast cancer. The plastic bottles may contain commonly used plasticizers such as phthalates, nonylphenol (NP) and bisphenol-A (BPA). All three of these chemicals have an associated cancer risk.
This study aims to show that migration of these three chemicals into the mineral water takes place when the plastic containers are exposed to a temperature of 400C for a period of 10 days, thereby posing a potential human health risk.
Several popular local and international mineral water brands will be identified. Still water in plastic and glass bottles will be purchased from a local supermarket. The samples will be divided and one sample will be placed in an incubator at 400C and the second sample will be stored in the dark at room temperature for ten days. The samples will then be processed as required for the relevant bioassays and chemical target analysis. The samples will be assessed for estrogenic activity using the recombinant yeast estrogen screen (YES) and the T47D-KBluc reporter gene assay. Samples with estrogenic activity will be tested for the presence of the phthalates (DEHP, DEHA and DBP), NP and BPA. A scenario based human health risk assessment will assess the carcinogenic and toxic human health risks posed by estrogenic activity and the chemicals found in the bottled water.
Worldwide the purchasing and consumption of bottled water is increasing. Bottled water is often packaged in plastic bottles and may be stored for several months at varying temperatures. Various studies indicated that some of the components of plastic containers can migrate into the water content. Some of these components have endocrine disrupting properties with the potential to have negative effects on the endocrine systems of humans and wildlife. Many endocrine disrupting chemicals (EDCs) are also associated with the development of various cancers such as testicular, prostate and breast cancer. The plastic bottles may contain commonly used plasticizers such as phthalates, 4-nonylphenol (pNP) and bisphenol-A (BPA). All three of these chemicals have an associated cancer risk.
This study aimed to show that migration of the above-mentioned chemicals into the water content is increased when the plastic containers are exposed to higher temperatures, thereby posing a potential human health risk.
A survey was done to determine the different brands of bottled water available at six different supermarkets in Gauteng. The list included information on the brand, source (e.g. natural spring, public distribution system, etc.), location of source, treatment of water (e.g. UV treated, 0.2 micron filtered, etc.) and the supermarkets that supply each brand. Based on the survey ten brands were selected to be analysed in the study, and included brands from different sources, locations and purification methods.
For each brand of bottled water, four samples from the same batch were purchased to test two different storage conditions. The samples were stored for ten days at 20⁰C or at 40⁰C in the dark. One litre of each 27 sample was concentrated using a solid phase extraction (SPE) procedure for the extraction of EDCs in water samples.
Analysis of bottled water extracts
The estrogenic (female hormone) activity in the bottled water extracts were tested in bioassays. The samples were also analysed for specific target chemicals. The target chemicals included phthalates (DEHP, DEHA, DBP), BPA and pNP. Based on these results, a human health risk assessment was done to determine the health risks and risk of developing cancer from the consumption of bottled water.
Results – Bioassays
Estrogenic activity was measured in only two of the bottled water brands that were incubated for ten days at 20⁰C, but in eight brands that were incubated at 40⁰C. The activity was equivalent to the activity of 0.001 ng/ℓ to 0.003 ng/ℓ of the female hormone 17β-estradiol.
Results – GC-MS analysis
BPA was detected in the bottled water samples at concentrations ranging from 0.0009 ng/ℓ to 0.1 ng/ℓ. In general, BPA concentrations were slightly higher in samples stored at 40⁰C compared to samples stored at 20⁰C. All the other target chemicals were below the detection limit.
Results – Health risk assessment
In the bioassays none of the samples were above the trigger value of 0.7 ng/ℓ for estrogenic activity in drinking water. With chemical analysis, only BPA could be determined. Although the phthalates concentrations were below the method detection limit, a dose half of the limit of detection or the limit of quantification was considered. This was carried out to determine if there are any non-detectable risks which need to be considered. The hazard quotient for the alkylated phenols and phthalates were well below 1, indicating that these chemicals are unlikely to pose a human health risk from drinking 2 ℓ of bottled water every day. The carcinogenic risk was also well below the WHO acceptable risk of 10-5 for the chemicals analysed. Uncertainty analysis using Monte Carlo simulations indicated an extremely low risks of developing cancer (1 in a trillion people may develop cancer) from exposure to bottled water.
In general, estrogenic activity and BPA concentrations were higher in bottled water stored at 40⁰C compared to 20⁰C, indicating that storage temperature might have an effect on the migration of EDCs into water content. Although the estrogenic activity and BPA concentrations were higher in bottled water stored at 40⁰C, the samples posed a more than acceptable risk for a lifetime of exposure, presenting with risks 1000 times smaller than the acceptable guideline values. Based on the Monte Carlo simulation for phthalates, which all measured below the detection limit of 0.1 ng/ℓ, the potential risks posed by phthalates in bottled drinking water were negligible. Even though the human health risk from drinking bottled water was extremely low, it should be kept in mind that it will add to the total human health and carcinogenic risk when combined with other exposure risks. Based on the observation that estrogenic activity and BPA levels were slightly higher in bottled water samples stored at 40⁰C, it is therefore recommended to rather store bottled water at room temperature or below to minimize exposure.