Thierfelder Tomas, Sandström Elin
Department of Biometry and Engineering, Swedish University of Agricultural Sciences, P.O. Box 7032, 750 07 Uppsala, Sweden.
Sci Total Environ. 2008 Aug 25;402(1):106-12. doi: 10.1016/j.scitotenv.2008.04.035.
Through the history of railways, wooden crossties impregnated with potentially hazardous creosote tar have supported the rails. With impregnated crossties having a lifespan of approximately 50 years, their creosote content is considered as quite safely stored while in dug-down usage. This situation of relative safety does, however, change into acute risk upon replacement and destruction. Carrying a highly flammable content, creosote crossties discharge a pulse of carcinogenic PAH compounds if burnt as ordinary waste. Safe destruction is therefore required if concentrations exceed a critical limit stipulated by the European Union. Since safe destruction is a process of considerable expense, there is a tendency among financial stakeholders to underestimate the creosote content of used railway crossties. In order to actually test whether concentrations generally exceed the critical limit, a set of used creosote ties was therefore sampled while still situated in the railway embankment. With a standard sum of sixteen PAH compounds used as an expression of their total creosote content, the generic concentration was formally inferred and found to significantly exceed the critical limit. The same applies to the fraction of seven carcinogenic PAH compounds, that alone exceed the stipulated limit for hazardous waste. It was also found that the material of railway embankments, whether or not the crossties were used in switches and/or railway yards, and sample depth within the crossties, has a significant effect on creosote concentrations. Regardless of the status of these factors, the concentrations significantly exceed the critical limit that defines hazardous waste within the European Union.
在铁路发展历程中，浸有潜在危险杂酚油的木质枕木一直支撑着铁轨。浸油枕木的使用寿命约为50年，在深埋使用时，其杂酚油含量被认为储存得相当安全。然而，在更换和销毁时，这种相对安全的状况就会转变为严重风险。杂酚油枕木含有高度易燃物质，如果作为普通废物焚烧，会释放出致癌的多环芳烃化合物脉冲。因此，如果浓度超过欧盟规定的临界限值，就需要进行安全销毁。由于安全销毁成本高昂，金融利益相关者往往低估废旧铁路枕木的杂酚油含量。为了实际测试浓度是否普遍超过临界限值，因此在一组仍位于铁路路堤中的废旧杂酚油枕木上进行了采样。以16种多环芳烃化合物的标准总和来表示其总杂酚油含量，正式推断出其一般浓度，并发现显著超过临界限值。七种致癌多环芳烃化合物的含量也同样如此，其单独含量就超过了危险废物的规定限值。还发现，铁路路堤的材料、枕木是否用于道岔和/或铁路货场以及枕木内的采样深度，对杂酚油浓度有显著影响。无论这些因素的状况如何，浓度都显著超过了欧盟界定危险废物的临界限值。
