二恶英多氯联苯的结构

PCDD总体结构由Edgar181——自己的工作。地方政府投资公司ensed under Public Domain via Wikimedia Commons

我们的环境（从我们呼吸的空气到我们吃的食物）对我们的健康，包括癌症的风险影响，这不是新闻。

But while some of the links between our environment and cancer are proven, evidence on other possible risks isn’t as convincing. When it comes to chemicals and cancer there seems no end to the media debate. But what does the evidence show?

媒体已经广泛争论二恶英。还有一项新的研究，发表在《期刊》上Breast Cancer Research,在我们的饮食和乳腺癌风险中查看二恶英。那么，这项最新研究增加了什么呢？

First a little background.

What are dioxins?

Dioxins are mainly released from certain industrial processes, and from burning waste – especially some types of plastic, like PVC. But because we now know that these processes release dioxins, they’re largely regulated and the World Health Organisation (WHO) estimates that dioxin levels today are about1970年代的10％.

Never far from the headlines

研究表明，某些二恶英的水平很高可能对健康有害，国际癌症研究机构（IARC）将一种二恶英（TCDD）归类为对人类的致癌。但是近几十年来，产生的TCDD量迅速下降。

But studies looking at dioxins and cancer aren’t perfect. Some of them have looked at animals given very high doses of dioxins, well above anything the general public would be exposed to. Other research has looked at groups of people whose jobs expose them to very high levels of dioxins. But these jobs often expose people to other chemicals which can increase the risk of cancer too. So teasing apart the role of individual chemicals is hard.

What these studies do tell us is that in principal, certain dioxins can cause cancer – but principal and practice can differ. And the levels of dioxins that most people would be exposed to are far smaller than the levels used in this type of research.

看着人

For most people, the main source of exposure to dioxins is through food and drink. So looking at diet, dioxin intake and whether a person goes on to develop cancer helps us understand what’s going on.

And the latest study has done just that, studying over 63,000 French women.

该小组分析了女性饮食，估计其二恶英摄入量，并平均跟随她们15年，以寻找患有乳腺癌患者的饮食二恶英的差异。

总体而言，有97％的妇女在WHO和欧洲食品安全局（EFSA）设定的二恶英暴露的安全范围内。即使在饮食量最高的女性中，乳腺癌的风险也没有增加。

这是对人类食物中乳腺癌风险和二恶英摄入的首次研究。与任何科学研究一样，结果的复制使我们对它更有信心。这项研究使我们对二恶英的暴露如何影响人群的健康有了一个很好的了解，但需要复制。

没有研究是完美的。For this latest analysis, information on diet was only collected once in 1993. Although the questionnaire used to collect information aimed to look back comprehensively over the past 12 months, we can’t be sure that a diet reported at the beginning of the study stayed the same throughout follow up.

因此，这项研究为我们提供了饮食时间的快照，但意味着我们不能确定所研究的女性的饮食不会改变，这可能会影响其饮食中的二恶英暴露。

The questionnaire was used to estimate the levels of dioxins in the women from this study – so any change in diet, body weight or levels of dioxins in food mean that the estimate could be less accurate.

但是幸运的是，全球二恶英的水平有所下降，现在是过去几十年中其水平的一小部分。

那么，最新研究如何适应二恶英和癌症的更大情况？

Water everywhere but not a drop to drink…

二恶英周围最持久的神话之一是它们从塑料水瓶中浸出，导致癌症和其他健康问题。

There is something which may seem logical in the argument that plastics give off chemicals that are detrimental to our health. The arguments are also often put forward using very emotive language, and are falsely attributed to credible sources like Johns Hopkins University in the US – all of which seem to add to its credibility.

But in fact, Johns Hopkins haverefuted the claims说没有充分的证据表明在水瓶中使用的塑料中甚至存在二恶英，没有convincing scientific evidenceto back up a link between using them and developing cancer.

多少是太多了？

由于高浓度的二恶英会影响健康，因此它们受到仔细控制和调节。EFSA已经确定了欧洲的安全水平，考虑到研究细胞，动物和人中的二恶英的研究，以设定二恶英暴露的最大限制。该限制还具有安全保证金，以说明研究没有明确削减的任何领域。

即使有了这个严格的安全限制，绝大多数人就会在其暴露范围内很好地落在其中。这远低于已证明对人们和动物研究中的健康产生任何影响的水平。

还要仔细监测欧盟的食物，以了解包括二恶英在内的许多不同物质。该监控是作为备份的备份 - 确保我们的食物符合EFSA科学小组在欧洲设定的质量标准。

Stable evidence

Lifestyle factors we can control, like diet, can have a big impact on our health, including our chances of developing cancer. But there are many things we can do to help stack the odds in our favour.

More than 4 in 10 cancers在英国，可以通过改变生活方式的改变，例如戒烟，减少酒精摄入量，身体活跃，吃健康的饮食习惯以及在阳光下保持安全。

While this latest study isn’t perfect, it reassuringly doesn’t show a link between exposure to dioxins and breast cancer risk.

It can often appear from media headlines and internet hype that the picture is changing very rapidly when it comes to the environment and our health – especially in the volatile world of chemicals and cancer. Actually, the evidence is much more stable.

该帖子的一个版本也出现在英国癌症研究Science blog.