Flame wars 火焰战争

IN MANY ways DDT was a miracle chemical when its efficacy against biting insects was discovered at the start of the second world war. Its widespread use against malarial mosquitoes saved countless lives. What was not known at the time, however, was DDT’s propensity to accumulate, persist and damage the environment.

当第二次世界大战伊始发现它抗蚊虫叮咬的功效之后，滴滴涕在许多方面都成为一种特效化学药剂。它广泛用于抵抗传染疟疾的蚊虫，拯救了无数生命。然而在那时没有人知道，滴滴涕有富集性，稳定性并且破坏环境。

Similarly, over the last 30 years flame-retardant chemicals known as polybrominated diphenyl ethers (PBDEs) have been widely used, although little is known about their broader effects. They are employed in furniture, carpeting, bedding, textiles, electronics and plastics to reduce the risk of ignition and slow down the rate at which things burn. But such is their persistence that they can also be found in soil, sediment, food, air and house dust, and 97% of Americans have detectable levels in their bodies. They are ubiquitous, in small amounts, in industrialised nations.

类似地，在过去的30年里，像我们知道的多溴二苯醚（PBDEs）等阻燃化学药剂也被广泛应用，但我们并不了解它们具有的其他功能。阻燃剂广泛应用于家具，地毯，卧具，纺织品，电子器件以及塑料制品领域，有助于降低物品起火风险，延缓物品燃烧速率。但由于其强稳定性，它也可以在泥土，沉淀，食物，空气及室内尘埃当中找到。97%的美国人体内阻燃剂达到可检测水平。在工业化国家中，阻燃剂的含量不大，但无处不在。

Increasingly, questions are being asked about their effects on health. Animal studies have shown them to affect neurological and reproductive behaviour. So Kim Harley of the University of California, Berkeley, and her colleagues decided to look at whether levels of PBDEs in women affected their fertility. They took blood samples from 223 women on low incomes living in California, most of whom were Mexican, and asked them how long they had taken to become pregnant. Their research, published in Environmental Health Perspectives, found that each tenfold increase in the blood concentration of PBDEs was linked to a 30% decrease in the probability of becoming pregnant each month.

人们越来越多的提出阻燃剂对于健康影响的问题。动物实验表明它们影响神经系统和生殖行为，所以来自加州大学伯克利分校的金哈利教授与他的同事决定观察多溴二苯醚的含量多少是否会影响女性生育能力。研究人员采集了加州低收入家庭的223位女性的血样，其中大多数人为墨西哥裔，并询问她们多久会怀孕。发表在《环境与健康展望》的研究报告中指出，多溴二苯醚血液含量每提升十倍，每月怀孕的可能性降低30%。更多信息请访问：http://www.24en.com/

Because little work has been done on the effects of PBDEs on human health, this is an important study. But more work will be needed to confirm the result, says Tony Dayan, an emeritus professor of toxicology, because the study was based on a small, distinctive group.

由于多溴二苯醚影响人类健康的研究还刚刚起步，所以该项研究非常重要。已退休的毒理学教授托尼达扬称，确认该研究成果还需付出更多努力，因为研究只是基于一个狭小，特殊的群体。

If confirmed, the findings would be troubling. In North America, PBDE concentrations in humans have been doubling every four to six years since the 1970s, and are 20 times higher than in Europe. California’s residents have the highest exposures, which the authors speculate may be due to the state’s strict flammability legislation. In Europe the most suspect PBDEs have been banned for seven to eight years, says Dr Dayan. In America some are being phased out too. But they are so persistent that people are likely to be exposed to them for years. Dr Dayan says it could take two to three lifetimes for them to disappear from the population.

若被证实，研究结果将令人烦恼。在北美地区，多溴二苯醚在人体内的含量从20世纪70年代起，每四至六年翻一番，比欧洲人体内含量高20倍。加州居民接触该物质最多，研究人员推断可能是由于加州严格控制易燃物的法规造成。达扬教授称，在欧洲，那些最可疑的多溴二苯醚七八年前就已被禁用。在美国，一些品种也被逐步淘汰。但这些阻燃剂十分稳定，以至于人们可能会与其接触很多年。达扬教授称，可能需要两到三代人才能令阻燃剂在人群中消失。

Flame-retardant chemicals have undoubtedly saved many lives, but it seems possible that there have been some hidden costs. It would be tempting to think that the lessons of DDT have been heeded. However, Dr Harley says that at present even less is known about newer flame retardants.

毫无疑问，阻燃化学药剂拯救了许多生命，但它似乎也给人们带来一些隐性成本。我们很容易以为有关滴滴涕的教训（有好处，但是还有很多不为人知的危害）我们已经注意到了。但是，哈里教授说，目前，我们对较晚认识的阻燃剂的了解却更少（更多的危害是我们不知道的。）

【后注】：
DDT:DDT又叫滴滴涕，二二三，化学名为双对氯苯基三氯乙烷(Dichlorodiphenyltrichloroethane)，化学式(ClC6H4)2CH(CCl3)。中文名称从英文缩写DDT而来，为白色晶体，不溶于水，溶于煤油，可制成乳剂，是有效的杀虫剂。为20世纪上半叶防止农业病虫害，减轻疟疾伤寒等蚊蝇传播的疾病危害起到了不小的作用。但在上个世纪60年代科学家们发现滴滴涕在环境中非常难降解，并可在动物脂肪内蓄积，甚至在南极企鹅的血液中也检测出滴滴涕，鸟类体内含滴滴涕会导致产软壳蛋而不能孵化，尤其是处于食物链顶极的食肉鸟如美国国鸟白头海雕几乎因此而灭绝。1962年，美国科学家卡尔松在其著作《寂静的春天》中怀疑，DDT进入食物链，是导致一些食肉和食鱼的鸟接近灭绝的主要原因。因此从70年代后滴滴涕逐渐被世界各国明令禁止生产和使用。滴滴涕还成为中国环境保护事业的催生婆。

PBDEs:多溴二苯醚最大的用途是作为阻燃剂,在制造过程中被人为添加到复合材料中去,使其不易燃烧.目前,PBDE已被广泛用于电子电器设备,自动控制设备,建筑材料和纺织品等商品化产品.1999年,全球多溴二苯醚的总使用量达到了80多万吨.在这些产品的制造,使用,循环回收,或是抛弃的过程中,多溴二苯醚进入到空气,水,土壤的循环系统中,成为日常环境中到处扩散的持久性有机污染物,对环境和人类的威胁日益升高. 多溴二苯醚具有很强的脂溶性,可以沉积生物体的脂肪组织并进行累积.研究表明,多溴二苯醚具有和PCB(多溴联苯)类似的神经毒性,会对肝和神经系统的发育造成毒害,同时干扰甲状腺内分泌,可能致癌或引起生物性别错乱.因此,越来越多国家开始关注起了多溴二苯醚物质的使用.美国加州州政府已于2003年8月第一个宣布2007年后禁止制造和使用PBDEs.欧盟2004年8月13日正式出台了《电子垃圾处理法》,要求2006年7月1日以后投放欧盟市场的电气和电子产品不得含有多溴二苯醚.