1、 外文翻译 原文 Textiles as a Source of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans (PCDD/F) Material Source:Germany Bayreuth University Author:Michael Horstmann, Michael S. McLachlan Abstract Polychlorinated dibenzo-p-dioxins and dibenzofurans were measured in low- to high-ppb concentrations in se
2、veral pieces of new clothing from different manufacturers. It was shown that these contaminants are transferred from textiles to human skin during wearing. They were also present in shower water and were washed out of textiles during washing. Extensive evidence was found indicating that contaminated
3、 textiles are a major source of chlorinated dioxins and furans in non-industrial sewage sludge, dry cleaning residues and house dust. 1.Introduction Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) are ubiquitous environmental contaminants that have been measured in air and soil througho
4、ut the world. The relative concentrations of the commonly analysed tetra to octachlorinated PCDD/F homologues are generally similar in soils that are not associated with particular industrial sources1. Various transformations of this homologue pattern, often referred to as the combustion pattern, ar
5、e found in many other abiotic matrices 2. However, in several media, specifically sewage sludge 3, dry cleaning residues 4, 5 and house dust 6, a second, distinct pattern is commonly present (-Fig. 1). Although considerable effort has been invested in identifying the sources of this unusual pattern,
6、 particularly in sewage sludge, no satisfactory explanation has yet been found 7. In searching for the answer to this open question, we analyzed human epidermis. Fig. 1: Homologue patterns for the CI4-CIsDD/F: a) The “combustion pattern“ as measured in soil from the Bayreuth area (mean pattern from
7、5 samples); b) the “sewage sludge pattern“ (mean pattern from 12 undigested sludge samples collected in the Bayreuth wastewater treatment plant) 2 Experimental Numerous samples from a variety of matrices were analysed for PCDD/F. This paper summarizes the results of more than 10 different experiment
8、s. The purpose of each experiment and the sampling procedure employed are presented together with the respective results in the following section. All samples were extracted in toluol or n-hexane/acetone mixtures and cleaned up using modifications of published methods 3, 8. Twelve 13C12 labelled int
9、ernal standards representing all 10 homologue groups were employed. The HRGC/HRMS analyses were performed on a VG Autospec-Ultima at a resolution of 10 000. 3 Results and Discussion 3.1 Levels of PCDD/F in Human Epidermis Samples of stratum corneum (human scale) were collected from 8 volunteers of v
10、arying age and sex using an adhesive tape stripping method 9. An area of 0,06 - 0,09 m 2 on the back was sampled. The concentrations of the PCDD/F in the first stripping layer ranged from 1 000 - 7 800 pg/g and the homologue pattern was very similar to that found in sewage sludge. Also, non-2,3,7,8
11、substituted PCDD/F were identified, congeners which are normally not present in human tissue. In 5 cases three layers of the stratum corneum were sampled. The concentrations decreased with increasing depth in a similar manner for all subjects. The second layer contained on average 43 % of the amount
12、 in the surface layer while the third layer contained 33 %. Samples of epidermis and the subcutis were analyzed to further investigate the distribution of the PCDD/F in the skin. The epidermis was mechanically separated from the corium under the microscope. The non-2,3,7,8 substituted PCDD / F conge
13、ners were, as expected, not present in the subcutis samples, whereas the epidermis showed a mixture of the congener pattern in subcutis and that in scale. In Fig. 2 typical chromatograms of the C17DD are shown for subcutis, epidermis and scale. Whereas the concentration of 1,2,3,4,6,7,9-C17DD is 65
14、times less than that of 1,2,3,4,6,7,8-C17DD in the subcutis, its concentration exceeds that of 1,2,3,4,6,7,8-C17DD in scale. The concentrations of these two isomers are generally similar in combustion products, sewage sludge and other environmental samples, while 1,2,3,4,6,7,9-C17-DD is virtually no
15、n-detectable in living human tissue. Hence a ratio of 1,2,3,4,6,7,9-C17DD to 1,2,3,4,6,7,8-C17DD 0,1 in the stratum corneum can be regarded as an indicator of surface contamination of the skin. Fig. 2: Typical chromatograms of CI7DD in a) the subcutis; b) epidermis; c) stratum corneum. Peak 1 is 1,2
16、,3,4,6,7,9-C17DD, peak 2 is 1,2,3,4,6,7,8-C17DD Nine epidermis samples and nine samples of the underlying subcutis taken from different locations on the body of a middle aged male were analyzed. Although the PCDD / F concentrations in the subcutis were relatively uniform (eg. 490 + 90 pg/g fat for C
17、IsDD), the levels of 1,2,3,4,6,7,9-CI7DD in the epidermis ranged over 2 orders of magnitude. The highest ratios of 1,2,3,4,6,7,9-C17DD to 1,2,3,4,6,7,8-C17DD in the epidermis were found in samples from the abdomen (1.1) and the sole of the foot (0.8), while the ratios in the samples from the upper a
18、rm, thigh, scalp, and buttocks ( 0.08) were not elevated. Thus, the abdomen and sole of the foot were heavily contaminated from external sources, while the upper arm, thigh, scalp and buttocks displayed no evidence of PCDD/F from the environment. The results show that the contamination of the stratu
19、m corneum is very heterogeneous, both between individuals and between sites on the same individual. The similarity between the homologne patterns suggests that the PCDD/F in the stratum corneum and the PCDD/F in sewage sludge, dry cleaning residues and house dust could have a common source. The pres
20、ence of non-2,3,7,8 substituted PCDD / F congeners in the stratum corneum indicates that the compounds are not being transported from the subcutis to the surface. Indeed, the decreasing concentrations with depth below the surface of the skin show that the compounds are diffusing from the surface tow
21、ards the living tissue 10. 3.2 Sources of PCDD/F in Human Epidermis As the concentrations of PCDD/F in the air are too low to explain the PCDD/F levels in the stratum corneum, textiles were considered to be the most likely source. Thirty-five new textile samples, primarily cotton products, were anal
22、yzed for PCDD/F. Fig. 3 shows the frequency distribution of the CIsDD concentrations in these samples. Low levels were found in many cases ( PCDD/F 50 pg/g). However, several T-shirts had extremely high levels, with concentrations up to 290 000 pg/g ( PCDD/F). The homologue patterns in the contamina
23、ted textiles were similar to the patterns found in the skin with several exceptions where high levels of CIsDF were also present. Fig. 3: Frequency distribution of the C18DD concentrations found in 35 textile samples The high concentrations were found in different colored T-shirts from a number of c
24、lothing producers. Furthermore, the concentrations in identical T-shirts purchased at the same store varied by up to a factor of 20. This indicates that the PCDD/F do not always originate from a textile finishing process, as in this case a much more homogenous contamination of the fabric would be ex
25、pected. Two experiments were conducted to determine the effect of the textile concentrations on the skin levels. In the first experiment a sample of the stratum corneum (one tape strip) was collected from the backs of two volunteers (one male, one female), who thereafter wore uncontaminated T-shirts
26、 ( PCDD/F 50 pg/g) 24 hours a day. After two weeks stratum corneum samples were again taken from the backs of the volunteers and analyzed. The concentrations (F.PCDD/F) decreased from 1 500 and 3 800 pg/g at the start of the experiment to the level of the method blank ( 300 and 480 pg/g) after two w
27、eeks of wearing the uncontaminated shirts. These results were reproduced in a second experiment where the uncontaminated shirts were worn for only one week. During the following week the volunteers wore mildly contaminated T-shirts ( PCDD/F = 780 and 930 pg/g). The homologue concentrations in the up
28、per tape strip of the stratum corneum increased up to 90 times during the second week (-Fig. 4). The homologue patterns in the stratum corneum mirrored the patterns in the different shirts worn by each volunteer. This demonstrates a causal relationship between the PCDD/F levels in the T-shirts and t
29、he levels in the stratum corneum. Fig. 4: Plot of the PCDD/F concentrations in the surface layer of stratum corneum from the backs of two individuals (- Fig. 4 a, 4 b) after wearing uncontaminated T-shirts (E PCDD/F 50 pg/g) for a period of 1 week (Skin 1) and after wearing contaminated T-shirts for
30、 the following week (Skin 2). The third row shows the homologue pattern (not the concentrations) in the contaminated T-shirts 3.3 Transfer of PCDD/F to Other Matrices The discovery of the high levels of PCDD/F in some new textiles not only explains the contamination in human scale (and hence in hous
31、e dust due to the role of scale in dust formation); it also provides an explanation for the PCDD/F found in sewage sludge. The transfer of the compounds from the textiles to the skin indicates that the PCDD/F are not tightly bound to the fabric. To verify this, two contaminated T-shirts were washed
32、in a washing machine with two clean T-shirts. Seven percentof the PCDD/F in the contaminated T-shirts was transferred to the uncontaminated T-shirts and a further 16 % was present in the effluent. In a further experiment the concentrations in a new uncontaminated T-shirt were measured before wearing
33、. An identical T-shirt was worn for two days. One part of the shirt was analyzed immediately and a second part was washed and then analyzed. The concentrations increased from 20 to I 750 pg/g ( PCDD/F) during wearing. Washing removed 35 % of the PCDD/F. Thus, the PCDD/F in new textiles can be direct
34、ly washed out, can be transferred to the skin and subsequently transferred back to other textiles and washed out, or can be transferred to other textiles during washing, only to be washed out at a later date. In all cases PCDD/F enter the sewage system. Washing machine effluent was analyzed in sever
35、al different households. Similar quantities of PCDD/F were found in the effluent of white and colored laundry. The average concentration was 430 000 pg/load ( PCDD/F). Assuming a conservative washing frequency of 1 load/week and person 11, a rough estimate of the flux of PCDD/F from this source into
36、 the wastewater treatment plant (WWTP) was obtained. The fluxes of the six congeners that commonly make the largest contribution to the PCDD/F toxicity in sewage sludge are compared with the fluxes measured in the sludge of a WWTP serving a residential area in Table 1. On the basis of this limited d
37、ata set the washing machine effluent would account for 27 % - 94 % of the PCDD/F leaving the plant. This is in agreement with the results of a previous study showing that household wastewater is the major source of PCDD/F in non-industrial sewage sludge 12. Table 1: Comparison of the flux of six PCD
38、D/F congeners entering a residential WWTP from washing machine effluent and the flux leaving the WWTP in sewage sludge. The former was estimated by multiplying the average quantity found in 4 samples of washing machine effluent by 1 wash/week and the number of people served by the WWTP. The latter w
39、as calculated by multiplying the average concentrations measured in 6 sludge samples taken over a period of 2 months by the weekly sludge production rate. In view of the contamination of the stratum corneum one would expect shower and bath water to be a further source of PCDD/F. Analyses of the show
40、er water from 5 individuals yielded PCDD/F levels between 1 200 and 11 000 pg/shower, confirming this hypothesis. However, the contribution of this source to the PCDD/F load in the WWTP would appear to be considerably less than the input from washing machine effluent. This study clearly demonstrates
41、 a link between PCDD/F in new textiles and in sewage sludge. The homologue pattern in the textiles, as typified by the pattern in Fig. 4a, is present (with minor variations) in all intermediate matrices (- Fig. 5) and in sewage sludge (-Fig. 1).The mass balance calculation above makes the tie betwee
42、n washing machine effluent and sewage sludge particularly convincing. Although based on a limited number of samples, the variability of the concentrations in washing machine effluent and sewage sludge was quite small (less than a factor of 2). The analytical method itself has a reproducibility bette
43、r than +20 %. Fig. 5: Homologue patterns of the CI4-ClsDD/F in a) household wastewater (mean pattern from two samples); b) washing machine effluent (mean of 4 samples); c) shower water (mean of 3 samples); d) stratum corneum (mean of 5 samples); e) domestic dust (mean of 2 samples) The high variabil
44、ity of the PCDD/F levels in the contaminated textiles means that their contribution is difficult to quantify without conducting a much more extensive and costly survey of new textiles. However, the importance of this source is supported by the presence of the characteristic sludge homologue pattern
45、in the contaminated new textiles and also by the failure to identify other sources of PCDD/F in washing machine effluent. The theory that chlorine bleach can react to form PCDD/F in the washing machine has been disproved by others 13. The uptake of PCDD/F from the air was investigated by hanging unc
46、ontaminated T-shirts both indoors and out for a period of two weeks. The results (- Fig. 6) show that, despite the long exposure time, very little PCDD/F was accumulated and that the resultinghomologue pattern was distinctly different than the sewage sludge pattern found in the washing machine efflu
47、ent. The PCDD/F taken up from the air was a factor 75 less than the amount taken up from the skin when the same T-shirt was worn for 2 days. Finally, if one considers that the most contaminated T-shirt contained as much PCDD/F as the sewage sludge generated by one person over one year, and that a si
48、gnificant portion of this PCDD/F enters the sewage system, then the arguments implicating new textiles as a significant source of PCDD/F in sewage sludge become persuasive. Fig. 6: Plot of the C14-C18DD/F homologue concentrations in 4 identical new cotton undershirts following: a) unpacking; b) hang
49、ing for 14 days in the living room of an department occupied by non-smokers, c) hanging for 14 days in the living room of an appartment occupied by smokers; d) hanging for 14 days outside in winter on the University of Bayreuth campus, exposed to the wind but protected from precipitation Two research groups have extensively investigated the behaviour of PCDD/F in the dry cleaning process and come to the conclusion that these substances are brought into the cleaning machines with the textiles 4, 5. The non-polar solvents
