美国政府展开手机辐射对健康影响的研究

由美国联邦机构进行的一项为期两年半的研究显示，手机辐射与心脑肿瘤有关，至少对于大鼠来说，两者之间存在关联。

上周四，美国国家毒理学计划（NTP）发布了经同业评审的手机辐射对大鼠影响的部分研究成果。结果显示，受试对象患恶性脑胶质瘤和心脏神经鞘瘤的几率不高。

在即将公布的另外两份报告中，NTP将会披露全部研究成果及相关结果，包括对大鼠的实验结果。尽管今年晚些时候将会公布其他相关研究结果，但在2017年年底前，此类报告很可能仅用于同业评审和征求公众意见。

目前，研究人员称，他们在某些雄性大鼠身上发现的心脑类肿瘤“可能是由全身暴露”在射频辐射（RFR）中导致的。实验中，采用GSM和CDMA两种移动行业通讯标准作为RFR。

RFR为非电离辐射，即电子从原子或分子中分离时不携带能量。众所周知，包含X射线在内的电离辐射可能导致癌症的发生。目前，关于RFR是否会导致某种癌症，证据还远不充分。

在此，有两点非常重要，必须引起注意。首先，大鼠并不是人类。其次，该类实验中致癌的几率确实非常低。但由于手机科技普及性极高，因此即便是很低的致病概率也可能引起公众对健康问题的深切关注。

NTP项目的前负责人罗恩•梅尔尼克（Ron Melnick）称，根据《华尔街日报》报道，这项新研究“终结”了手机辐射没有危害这一说法。

但是，其他一些研究则表明，手机辐射是安全的。例如，上月发布的一项在澳大利亚进行的研究表明，澳大利亚的脑癌患病几率并未因手机普及而上升。

NTP实验中，将啮齿动物暴露在美国常用的典型蜂窝通信无线电射频中（其中为大鼠施加的射频频率为900MHz，小鼠为1900MHz）。从胚胎开始，贯穿于整个生命周期，每天暴露9小时。

广泛应用的GSM移动通讯标准辐射中，所有实验组的雄性大鼠患恶性脑胶质瘤的几率并不高（为3.3%）。而数据显示，暴露于CDMA标准的高能无线电波中，恶性脑胶质瘤的发病率同样为3.3%。控制组中的大鼠，由于未受到RFR辐射，因而未发现患此类疾病。

相比之下，雌性大鼠发病的几率较低，高能GSM辐射下的雌鼠脑损害发病概率仅为 1.1%，在低能CDMA辐射情况下恶性病变发生概率为2.2%。

GSM和CDMA辐射暴露组中的某些雄性大鼠发生心脏损伤，但CDMA辐射下发生概率较高（高达6.6%）。与上述情况类似，控制组大鼠没有发生病变，且雌性大鼠患病率较低。

事实上，在为期两年的研究结束时，控制组大鼠比辐射暴露组的大鼠存活率低；研究人员称，若上述肿瘤为“后发疾病”，那么这一现象可能影响暴露组大鼠和非暴露组大鼠间的对比结果。

根据实验人员记录，“在研究后期或研究结束时死亡的动物中，大多都发现了患有神经胶质瘤。”“但是，在为期90周的研究中，发现暴露组中心脏神经鞘瘤发生概率较高。研究期间，控制组中的90只雄性大鼠约有60只存活，但是存在患肿瘤疾病的危险。”

代表全球手机运营商的GSMA称，过去二十年的研究未发现使用手机会导致任何健康风险。其发言人告诉《财富》记者称，“研究成果将由科学界结合全部已有研究，研究成果的一致性以及反响的重要性进行审议。” (财富中文网)

翻译：司慧杰/汪皓

A two-and-a-half-year study carried out by U.S. federal agencies points to a link between cellphone radiation and heart and brain tumors—at least, in rats.

The National Toxicology Program (NTP) on last Thursday released the peer-reviewed partial results of a study into the effects of mobile radiation on rats. It found low incidences of malignant gliomas in the brain, and schwannomas in the hearts of the subjects.

Two forthcoming NTP reports will lay out the full findings of the study and others like it, also involving mice. These reports will probably only be available for peer review and public comment by the end of 2017, although some additional results should be published later this year.

For now, the researchers say the brain and heart tumors that they observed in some male rats “are considered likely the result of whole-body exposures” to radiofrequency radiation (RFR) modulated using the GSM and CDMA mobile industry standards.

RFR is non-ionizing, which is to say it doesn’t carry enough energy to remove the electrons from atoms or molecules. Ionizing radiation, such as X-rays, comes with known cancer risks. The evidence for RFR being any kind of cancer threat has so far been extremely limited.

Two things are very important to note here. Firstly, rats aren’t people. Secondly, the incidences of tumors in these tests were indeed very low—although with the ubiquity of this technology, even a low risk could be a serious public health concern.

According to former NTP project leader Ron Melnick, quoted by the Wall Street Journal, the new study “ends” the notion that there is no risk from cellphone radiation.

That said, other studies have suggested cellphone radiation is safe. For example, a study in Australia, the results of which were released last month, showed no increase in brain cancer in the country that could be tied to the widespread rise in cellphone use.

The NTP tests involved exposing rodents to the typical radio frequencies used in cellular communications in the U.S. (at 900MHz for the rats and 1900MHz for the mice) for periods of around nine hours per day, starting in the womb and continuing throughout their lives.

The radiation using the widely-used GSM mobile communications standard resulted in low incidences (up to 3.3%) of malignant brain gliomas in all groups of male rats. Exposure to radio waves using the CDMA standard also caused statistically significant trends towards malignant gliomas (again, at 3.3%) at higher energies. There were no incidences of these lesions in control group rats, which were not exposed to RFR.

Incidences were lower for female rats, with just 1.1% of rats developing a brain lesion from GSM-modulated radiation at higher energies, and 2.2% developing malignant lesions from lower-energy CDMA-modulated radiation.

Heart lesions were again observed in some male rats in all the exposed groups, for both GSM and CDMA, although CDMA radiation caused significantly higher incidences (up to 6.6%). Again, the control group rats saw no incidences, and incidences were lower among females.

As it happens, the control group rats actually had lower survival rates at the end of the two-year study than those exposed to the radiation—the researchers said it was possible this could have had an effect on the comparison between exposed and non-exposed rats, if the tumors in question are late-developing.

“Most of the gliomas were observed in animals that died late in the study, or at the terminal sacrifice,” they wrote. “However, a relatively high number of the heart schwannomas in exposed groups were observed by 90 weeks into the study, a time when approximately 60 of the 90 control male rats remained alive and at risk for developing a tumor.”

The GSMA, which represents mobile operators around the world, stressed that previous studies over the last two decades have not shown any health risks associated with mobile use.

“The study findings will be considered by the scientific community in the context of the whole body of available research, the consistency of the findings and the importance of replication,” a spokesperson told Fortune.