Should you worry about reusing a plastic water bottle?
We seal drinks in single-use plastic bottles to keep them fresh. We take away leftovers after dinning out with plastic containers to avoid wasting food. It’s fair to say that plastic products make our life a lot easier such that we are using them extensively, perhaps even excessively.
It may be a good idea to reuse them to save resources and reduce environmental pollution. However, is it safe to reuse plastic bottles and containers?
The Story of BPA
We are all familiar with water bottles tagged with “BPA-free” and tend to believe that they are safer than their counterparts without such a claim. So what exactly is BPA? Why do we concern about it?
BPA is the abbreviation of bisphenol A, a member of bisphenol family. It is a major raw material for manufacturing epoxy-based can lining and polycarbonate bottles and containers. Trace amount of BPA residue is commonly found in PET bottles. In long-term storage or reused, aging bottles and containers, PET can degrade and generate BPA which then migrates into liquid contents.
As a hormone-like compound, BPA disrupts endocrine activities by competing with normal hormones in binding to the receptor. Hence, BPA can inhibit cell proliferation, brain development and fertility. That’s why we don’t want it to appear in things in contact with food and drink.
Hazard pictograms of BPA, retrieved from: https://jr.chemwatch.net/chemwatch.web/home
And There Are Many More!
Apart from BPA, plastic packaging may contain and slowly release many other hazardous chemicals over time. These chemicals are often toxic or endocrine disrupting and are suspected to associate with many chronic diseases such as heart disease and diabetes.
The aging of plastics per se is one reason for this. A major source of nasty substances is various additives used in plastics to yield desirable features. Typical examples include dyes, flame retardants, heat stabilisers and plasticizers that make plastics more flexible. Usually, additives are attached to plastics loosely so they are prone to leach into liquids. Moreover, plastics can have countless kinds of impurities and by-products which are difficult to predict but are nevertheless potentially dangerous.
Plastic = Poison?
To determine the hazards of a chemical on human health, we must consider both the dose and the identity of the chemical. Still take BPA as an example. Survey results from Australia New Zealand food standards assert that “dietary exposures of Australian consumers are low and within acceptable safe limits” with respect to it. To reassure consumers, producers are voluntarily phasing out BPA from their products, especially those for babies.
As a matter of fact, health risks associated to BPA are still controversial among scientists. Different studies have different conclusions on how significantly or certainly BPA harms human body. It is also challenging to produce concrete evidence that confirms the cause-and-effect relationship between BAP level in body and chronic diseases, partly due to our exposure to plenty of other chemicals.
In addition, BPA-free does not equal to risk-free. We must be cautious with alternatives of BPA, for they having a similar effect on endocrine. BPA analogues such as BPB and BPS, whose toxicity is not fully studied and regulated by authorities, can be even more dangerous than BPA. Fortunately, not all substitutes are as bad as it, a study shows that CHDM and TPA are much safer replacements of BPA.
Some Final Tips
There is no need to panic though scientists raise a few concerns about plastic bottles and containers. In reality, the diffusion of these chemicals is very slow. Being exposed to sunlight or high temperature during transport or storage does speed up the process. That’s a reason why we often see “store below 25 °C” or “away from direct sunlight” on packaging. You can make a safer choice by storing bottled drinks as suggested.
Anyway, the best way to bring down the health risks is simply to use glass or steel water bottles and food containers, and use plastic ones as few as possible!