25
Fuels & Lubes International Quarter Two 2016
The usefulness of chlorinated paraffins (CPs) as an
extreme pressure additive in metalworking fluid and in
a vast number of other applications for over 80 years is
undisputed. But why is there renewed interest in CPs
worldwide? It is easier to understand why, when several
simple questions are answered.
What do we really know about
chlorinated paraffins?
Chlorinated paraffins, also known as polychlorinated
n-alkanes, are basically divided into four classes, with a
push towards distinguishing a fifth. The most well-known
and well studied are the short chain CPs (SCCPs) with 10 to
13 carbons, then medium chain CPs (MCCPs) with 14 to 17
carbons, long chain CPs with 18 to 20 carbons and lastly,
the new kid on the block: very long chain CPs (vLCCPs)
with 21 or more carbon molecules. The carbon chain
length and degree of chlorination of CPs play an important
role in distinguishing different CPs’ properties that affect
their uses as well as their impact on people and the
environment.
Where can you find them?
CPs are practically found everywhere. From the Arctic
to the Antarctic, from East Asia to North America and from
Europe to Australia. They are almost literally in everything
as well. Studies have isolated them in air (atmospheric
and indoor), water (aquatic environment, rivers, lakes and
oceans), dust, sediment, soil and wastewater treatment
sludge/sewage sludge. Dated sediment core samples
representing 120 years have shown that increased levels of
CPs in sediment during the 1980s coincide with their rise in
production.
Interestingly, CPs have also been found in food, dairy
products, cooking oil (although they cannot explain why),
earthworms and other animals and human breast milk.
SCCPs in food samples were compared in Japan, China and
South Korea in the 1990s and the 2000s. The preliminary
results show that there was a significant increase in SCCPs
in the food samples fromBeijing, China, wherein levels in
2009 were twice as high compared to levels in 1993. There
were no SCCPs in the 1994 Seoul, South Korea samples
and only one sample had traces of SCCPs in 2007, while
the number of samples from Japan with SCCPs in the
1990s and in 2009 was constant. Air samples from China,
Japan and South Korea were also studied and yielded
similar results; highest levels of SCCPs were found in
China. Results were consistent with the fact that production
of SCCPs in China has risen so much more compared to
Japan and Korea. China is the biggest producer of CPs,
with an annual production of 150 metric kilo tonnes (kt) in
2003, rising to 600 kt in 2007, then to 1,000 kt in just two
years (2009). In comparison, Japan’s production was only
approximately 0.5 kt per year.
将氯化石蜡（CP）用作金属加工液中的极压添加剂及其他众多领域已
有80多年的时间，从未间断。但为什么全球对CP又燃起了新的关注？回
答了以下几个问题，就可以简单地了解为什么了。
我们对CP到底了解多少？
氯化石蜡又称为多氯正烷烃，主要分为四类，且有人在力推第五类。
最常见的，也是研究最多的是短链氯化石蜡（SCCP），有10-13个碳；其
次是中链氯化石蜡（MCC），有14-17个碳；长链氯化石蜡（LCCP），有
18-20个碳；以及最新分类的超常链氯化石蜡（vLCCP）有21个及以上的
碳。CP的碳链长度和氯化程度在区分不同CP的性质时非常重要，这些
不同的性质决定了它们不同的用途，以及它们对人类和环境的影响。
哪里可以找到它们？
CP几乎无处不在。从北冰洋到南极，从亚洲到北美，从欧洲到大洋
洲。可以说它存在于任何东西里。研究中，已从空气（室外大气和室内空
气）、水（水生环境、河流、湖泊和海洋）、灰尘、沉积物、土壤和废水处
理的污泥/下水道污泥中分离出CP。代表了120年的沉积物核心样品显
示，CP在沉积物中的浓度从上世纪八十年代开始上升，这与其产量的增
加时间相同。
此外，在食品、乳制品、烹饪油（虽然不能解释为什么）、蚯蚓及其他
动物和人类的乳汁中发现了CP。在比较了日本、中国和韩国在上世纪九
十年代和2000年代食品样品中SCCP后，初步发现中国北京食品样品中
的SCCP浓度显著上升，其2009年时的浓度是1993年时的两倍。韩国首
尔1994年的样品中没有SCCP，2007年的样品中只有一个有痕量的CP。
而日本的1990年代与2009年的含SCCP样品数量相同。对中国、日本、
韩国的空气样本进行研究时，也得出了类似的结论：中国的SCCP浓度
最高。这个结果与中国SCCP产量增加幅度大于日本和韩国这个事实一
致。中国是最大的CP生产国，2003年的年产量为15万吨，到2007年上
升到60万吨，然后在两年内（2009年）达到100万吨。与之相比，日本的
产量仅为每年500吨。
它们如何影响动物？
简单地讲，动物摄取CP，CP成为其食品中的一部分，并随食物链累
积，食物链顶层的浓度最高。野生的大型动物和小型动物体中都探测到
SCCP：从无脊椎动物到鱼类、虾类、鸟类到海豚、江豚、海豹、白鲸。“生
物累积性”是指在不断消费或暴露于CP时，CP浓度的不断增加。想象一
下一个美国密歇根州Flint的儿童，不断饮用被铅污染的水，并在这种水
中沐浴，那么就像SCCP一样，会出现生物累积。“生物放大”是指从食物
链的一个环节到下一个环节的过程中CP浓度上升。虽然一些研究人员
研究了SCCP的生物累积和生物放大程度，并进行了量化，但没有实用
性的提示多少是安全浓度、多少是不安全浓度，或得出在特定暴露或污
染水平下对环境和健康的影响。
CP对部分水生生物的毒性非常强，但在实验室研究中并非总是如此。
哺乳动物实验室研究表明SCCP的急性口服毒性较低，且没有显示出诱
变潜力，但它确实显示了对肝、肾、甲状腺和甲状旁腺的毒性。在一些研
究中，动物出现了肿瘤/癌变。国际癌症研究机构（IARC）根据这些实验
将SCCP归为有可能致癌物（2B类）。
它们如何影响人类？
专家并不十分确定，因为目前还没有高质量的流行病学研究，也没有
职业暴露健康研究，更不用说随机控制人体试验来明确确定人体毒性。
