寶特瓶的溫柔口角

【Comment】

近來，我與周遭（以女性為主）因寶特瓶 (PET) 展開數次溫柔的口角。頻率雖然沒有中越撞船171次之多，而且溫柔，但也很夠嗆的。

幹，又是P博士！

口角的觸媒是媒體報導：礦泉水開封後最好趕緊喝完，因為會滋生細菌，所以千萬不要再度使用（一週為上限）。至於車內的礦泉水寶特瓶身會析出致癌物質云云。

我的疑問是：除了玻璃（我很懷疑），哪種容器不會析出其他物質？

印象中寶特瓶在約1980年被製成瓶子之後，因為好用、乾淨、輕盈、便宜（用完即丟）、耐壓力、瓶蓋耐滲水等，被推崇為終極容器而迅速普及。一段時間，台灣的垃圾中有巨量的寶特瓶，環保署因而祭出押瓶回收機制。

由於前述媒體的報導，關心家庭成員健康的現代女性便信守奉行媒體的「指示」：礦泉水喝完就丟瓶，絕不重複使用。卻忘記問：既然瓶蓋比多數市售水壺、水瓶還有絕佳的鎖水性，為何細菌會進入？反而醬油瓶、飲料卻不會？

我很懷疑這又是商業的必要之惡！

由於礦泉水價格昂貴，比自來水貴上千倍（很多礦泉水只是使用「自來水體」過濾後裝瓶），是一本萬利的好買賣。但注重環保（少製造垃圾）的人，會買礦泉水目的在買瓶子重複使用。

這樣廠商就虧大了──過去寶特瓶的優點變成商機殺手。這可不行。

於是，出現前述的媒體報導。

總之媒體報導的目的在暗示消費者：買「新的」，不要重複使用瓶子。為此，廠商還特別開發出扭扭瓶，讓消費者可以在喝完之後扭一扭瓶身後丟棄，順便為自己下一次的消費鋪路。

實際上，消費者剛買的「新的」礦泉水已經裝填、儲存不知多久？

而廠商有了消費者幫忙，口袋麥克麥克。不知替員工加薪了沒？

看到商業在其中的角色之後，我去看報告。

媒體報導指涉的研究主要指的是延長的儲存與升高的溫度 (prolonged storage and elevated temperature)，而這多半是廠商自己的責任，也都不是一般消費者僅僅做裝水的重複使用會遇到的。報告建議做進一步研究以便確定，換言之，自己也不敢將話說死。

有很多生活健康知識，有時代性、研究變數的局限性、以及商業性，狠複雜的。

盡信媒體不如自己思考。

因此，我這樣認為：只是當成外出時的裝水容器而已，就大膽重複使用礦泉水瓶吧！

Polyethylene Terephthalate May Yield Endocrine Disruptors

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2854718/

Discussion

The available research suggests that the concentration of phthalates in the contents of PET bottles varies as a function of the contents of the bottle, with phthalates leaching into lower pH products such as soda and vinegar more readily than into bottled water.  Temperature also appears to influence the leaching both of phthalates and of antimony from PET, with greater leaching at higher temperatures.

The effect of temperature may account for some of the variation in the results noted previously.  For example, Pinto and Reali (2009) noted that “cell toxicity was observed for water samples of the same lot of three different brands purchased from the same retailer”; they conjectured that “toxicity might be attributable to the storage conditions of the product.”  Perhaps that retailer left the bottles exposed to the hot sun, whereas other retailers did not.

Lower-pH condiments such as table vinegar and salad dressing may warrant particular attention.  The findings of Farhoodi et al. (2008) suggest that ingesting several servings of salad dressing that had been stored in a warm warehouse for a month might result in a dose of DEHP on the order of several hundred micrograms, possibly reaching the reference dose limit of 20 μg/kg/day (U.S. EPA 2006).

Conclusion

The evidence suggests that PET bottles may yield endocrine disruptors under conditions of common use, particularly with prolonged storage and elevated temperature.  Important questions for future research include the following: What substances in the water are responsible for the estrogenic effects observed in the bioassays—is it one or more of the phthalates, and/or antimony, and/or as yet unidentified substances?  How do variations in the composition and manufacture of PET influence the leaching of these substances into the contents of the bottle? Would special measures—such as a special coating on the inner wall of the bottle (e.g., Pennarun et al. 2004), or transportation under controlled-temperature conditions—minimize the leaching of these substances into the contents?  Because of the widespread use of PET plastic worldwide in containers for water, soda beverages, and condiments, the safety of PET under conditions of common use certainly merits further investigation.