我们吃了多少塑料

Microplastics Dose

塑料很轻,有延展性,又很耐用,用途之广泛,以至于白色垃圾随处可见,连我们体内都有。一项新研究发现,人类正在摄入数目惊人的微型塑料。

微型塑料,根据现有定义,是指尺寸小于五毫米的塑料。人们通常认为微型塑料跟米粒或芝麻一般大小,而目前人们接触的大多数微型塑料比芝麻小得多,往往小到看不见,至少肉眼看不见,所以很多人听说了微型塑料的数量,都感到很惊讶。

考克斯是加拿大维多利亚大学海洋生物学专业的在读博士。他在环境科学与技术杂志上发表了这项研究。微型塑料来源很多,有可能是大块塑料上掉下来的,也有可能最开始就设计得很小。

为了深入研究,考克斯和团队收集了过去的文献资料,资料计算了我们经常摄入的物品中微型塑料的数量,比如自来水、瓶装水、糖果、海鲜,甚至我们呼吸的空气。通过分析,他们查出了人每年摄入的微型塑料最低值,而且牛肉、家禽、蔬菜、奶制品这些常见食品还不包括在内,因为这些食品的微型塑料数据他们还不掌握。调查范围其实只占人们热量摄入的百分之十五。

即便人们摄入的大量食物都未统计,结果仍然表明,人每年摄入了至少七万四千到十二万一千个微型塑料颗粒。而且喝瓶装水的比喝自来水的摄入量多。所有这些塑料摄入都是安全无害的吗?我们还真不知道。

这是我们对微型塑料人体摄入剂量的首次估算。从毒理学和生态毒理学的角度看,剂量是判别毒性的一项重要参考因素。虽然此次研究首次公布了微型塑料的估值,但由于很多数据我们并不掌握,所以肯定存在低估。

原文

Plastic is lightweight, malleable, durable. But it has also become so widespread that it’s ending up in a lot of unwanted places—including our own bodies. That’s according to a new study, which found that humans are consuming a shocking amount of so-called “microplastics.”

“Microplastics, the kind of current working definition, is plastic less than five millimeters. So people commonly equate that to something like a grain of rice or a sesame seed and down in terms of size class. I will say that most of the microplastics that people are interacting with are quite a bit smaller than the sesame seed size, which I think always kinds of shocks people when we start talking about the numbers because they kind of can’t see a lot of these things, at least with the naked eye.”

Kieran Cox, a PhD candidate in marine biology at the University of Victoria in Canada and one of the authors of the study, which is in the journal Environmental Science & Technology. Microplastics come from numerous sources. They can be pieces shed from larger plastics or they may have been designed small to begin with.

For their study, Cox and his team pulled together past scientific literature that calculated the number of microplastics in things we commonly consume, such as in tap and bottled water, sugars, seafood—even in the air that we breathe. This analysis helped them figure out the baseline amount of microplastics that people are consuming every year. They couldn’t include common foods like beef, poultry, vegetables and dairy in their analysis because data on them doesn’t exist yet. In fact, their study could account for only 15 percent of people’s caloric intake.

Even missing the majority of what people swallow, the research revealed that—at the very least—humans appear to consume somewhere between 74,000 and 121,000 microplastic particles every year. That number goes up for people drinking bottled water rather than tap water. Now, is all this plastic ingestion safe? We simply don’t know.

“This is kind of the first estimate of dose, you could say, right? So if you're thinking in terms of toxicology and ecotoxicology, dose is a very important factor to think about, and so this kind of presents the first estimate, but it is very much an underestimate because of what we don't know.”

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