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More research?

Posted by entelechy on 20 Sep 2013 at 18:55 GMT

Are you contemplating more research on possible differences in the plastic containers used? There are a multitude of color, size, shape, thickness variations apparent just from walking down a supermarket water aisle. Are some brands (testing with less contaminated water) using novel (more costly) plastics that might be more chemically inert? Was there any correlation (inverse or not) between retail price and contamination?

Also, what different technologies are used at bottling plants which might contribute to contamination before water is bottled? And what is the time elapsed between bottle manufacture date and bottle filling date? Do some brands have longer cure times for their bottles?

Finally, wouldn't publishing the names of water brands along with the test results activate market forces which might push manufacturers to 'compete' on the area of contamination?

No competing interests declared.

RE: More research?

Martin_Wagner replied to entelechy on 23 Sep 2013 at 13:07 GMT

Dear entelechy,

Many thanks for your questions and comments!

Your first questions refer to the influence of the plastic packaging on the chemical contamination of bottled water. While we have demonstrated that estrogen-like chemicals may originate from the plastic bottle (DOI: 10.1007/s11356-009-0107-7; 10.1016/j.jsbmb.2010.10.007), the picture is not that clear cut in our recent study. The antiestrogenic and antiandrogenic activity in products packed in PET is significantly higher compared to glass (pooled data from the five product pairs 1-10 shown in Figure 1, p < 0.02 and p < 0.0001, respectively, reanalyzed using nonparametric Kruskal-Wallis with Dunn’s post test). However, the differences in the packaging material are less pronounced compared to our previous studies (activity app. 10% higher in water from plastic bottles). Moreover, the levels of DEHF are not statistically different in plastic and glass-bottled water. This implies that the packaging (if at all) only slightly contributes to the contamination with antiestrogens and antiandrogens.

Concerning the chemical inertness of plastic packaging: While there are certainly differences between the plastic types, polymers cannot be inert. This is simply because of their chemistry (large polymer chains/nets, addition of non-covalently bound chemicals (e.g., plasticizers), incomplete polymerization).

Having said that, most of the plastic-bottled water sold worldwide is packed in polyethylene terephthalate (PET) and all of our "plastic samples" were PET bottles. While the polymer type is the same, there are obvious differences in the bottles' shape, wall thickness, color, use (single-use and reuse bottles), and price. We found no apparent correlation of these factors with the biological activity.

However, there may be less obvious differences in the PET composition the individual manufacturers use for making their bottles. One example is the use of antimony as PET catalyst in Europe, while Japanese manufacturers rely on titanium (DOI: 10.1021/es061511). Accordingly, each manufacturer will use different batches of building blocks (containing different impurities) as well as different additives (processing aids, colorants, aldehyde scavengers etc.). Since the manufacturers do not disclose their exact PET composition, we cannot account for those factors.

Regarding your questions on the bottling process: Like in case of the PET composition, we do not have sufficient insight to provide authoritative answers. In principle, however, there are two sources of chemical contamination during bottling include: (1) residual cleaning agents remaining in tanks and pipes and (2) leaching of chemicals from tank/pipe/pump/sealing materials. There is almost no published data on this issue. The only studies we are aware of are the ones by Di Bella et al. (DOI: 10.1021/jf0100043) demonstrating a phthalate contamination of oil via plastic piping and the work of Shao et al. reporting increased estrogenic activity and EDC concentrations in drinking water during piping delivery (no DOI, citation below). These demonstrate that a contamination during bottling is not unrealistic but deserves further research.

Regarding publishing the brands' names to activate market forces: We are convinced that it is not our role as independent researchers to act on market forces. We prefer to stick to the science and leave market regulations to the governmental agencies (and the political decision-makers) in charge.

Martin Wagner
Goethe University Frankfurt am Main

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References:
Shao, X.-L., Ma, J., and Wen, G. (2008). Investigation of endocrine disrupting chemicals in a drinking water work located in Songhua River basin. Huan jing ke xue= Huanjing kexue, 29(10), 2723–2728 (in Chinese).
Shao, X.-L., Wen, G., and Ma, J. (2009). Survey of estrogenic activity of Songhua River water and drinking water of Harbin. Huan jing ke xue= Huanjing kexue, 30(5), 1362– 1367 (in Chinese).

No competing interests declared.