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In summary, a total of 38 publications were identified, published between 2007 and 2014, describing DP concentrations in the environment. Environmental compartment investigated were household dust, air, water, sediment, soil, and biota (fish, bird eggs and food). Amongst these publications also two review articles were recorded (Xian et al. 2011 and Sverko et al. 2011), summarizing the finding up to 2010 from public literature.

Household dust In one publication household dust was analyzed for DP content based on 69 samples taken between 2002 and 2003 and 7 samples taken in 2007. Concentrations of DP found in the samples were 14 and 22 ng/g DP in dust, respectively.

Air concentrations of DP In nine publications air concentrations of DP were determined, either directly in air or in airborne particulates or indirectly, deposited in tree barks. In summary, highest concentrations were found close to point sources being either the two manufacturing plants for DP worldwide (in Niagara Falls, US and in Huai’an in the Chinese province of Jiangsu) or in proximity to e-waste recycling sites in China, having a very poor level of hygiene standards and characterized apparently by small companies and family undertakings incinerating cables and electronic equipment to recover metals inside without appropriate air emission controls. Differences were also seen between larger residential areas and rural areas with much lower population densities, attributable mainly to release of DP from electro and electronic equipment in use. More than 99% of DP in air was found bound to particulates and thus transport through air is dominated by particulate transport (dust particles). When concentrations found in air were dominated by point sources, such as in the Great Lakes area in the US and in Jiangsu province, air concentration appeared to decline with the square of distance, confirming the point sources dominating these findings. Highest DP concentrations found were 0.8 – 20 pg/m³ in the Great Lakes Area and 7.7 – 26.7 ng/m³ in China, Jiangsu province (both close to the two DP manufacturing sites), whereas concentrations in rural areas were typically in the range below 10 pg/m³ and in urban areas greater 10 pg/m³ were found (e.g. 7.1 - 15.4 pg/m³ in Osaka, Japan). Ren et a. reported that of the 46 sites where DP was not detected in China, 44 were rural, corresponding to only 38% of the 71 rural sites where DP was measured. On the other hand, DP was observed at 93%, or 24 of the 26, of the urban sites. Hence, where no point sources are attributable to release of DP a correlation of population density with DP concentration found in air can be made. In some publications the difference of syn- and anti-DP was assessed but findings were not consistent, showing no clear trend for alteration of the syn- to anti-DP ratio in air. Finally, Möller et al. reported on air sampling analysed for DP taken aboard a German research ship (Polarstern) when travelling from Greenland to the Antarctica. Along the Atlantic atmosphere, the highest concentration was observed at the east coast of Greenland and in the English Channel originating from continental air passing Western Europe indicating Western Europe as source region of DP in the marine environment. Thereby, the fractional abundance of the syn isomer (f syn) increased with decreasing northern latitude from 0.37 which is close to the commercial mixture (f syn = 0.32) to0.67 showing a stereoselective depletion of the anti-isomer likely caused by UV-sunlight during LRAT. The concentrations of DP ranged from 0.05 to 4.2 pg/m³ in the atmosphere. The occurrence of DP even in the remote areas of the Arctic and Antarctica suggests that DP is susceptible to long-range atmospheric transport (LRAT).

Water concentrations of DP

In five publications results from water sampling were reported, indicating DP concentrations. Results showed wide variation, as in Harbin, located in northeast of China at Songhua River no DP concentrations in the water phase were detected (Ma, 2011) and just one year before Qi (2010) found DP only in some samples taken from the same river (in 15% of rural areas, 27% of harbor area and 67% of urban areas along the river).He (2014) analysed DP in the Pearl River Delta, South-China. DP was detected in both dissolved and particulate phases at concentrations ranging from 1.2 to 3.3 pg/L and from 0.24 to 0.78 ng/L, respectively. The values found in the dissolved phase were close to the quantification limit. The syn- to anti-DP ratio was found not being significantly different from the technical material ratio for the isomers. Xiang 2014) investigated a waste water treatment plant in Shanghai city (China) analyzing influent, final effluent, and dewatered sludge for DP concentrations and other flame retardants. Also here, in the dissolved phase of the influent, DP concentrations were below the limit for quantification and only in the particulate phase of the influent water DP was quantified (average 0.46 ng/L).In the WWTP DP is mainly bound in sludge of the two sedimentation basins and is found in the dewatered sludge in concentrations of 1.1 - 2.0 ng/g dw. o DP could be quantified in the effluent water of the WWTP. For all Shanghai waste water treatment plants an annual release of 164.8 g DP was estimated, based on the analysis of one WWTP, whereas the number for polybrominated diphenyl ethers (PBDE) were more than an order of magnitude higher (6370 g). Syn- and anti-DP ratios were similar to those of commercial products. No significant seasonal variations were observed in the four seasons. Finally, Möller et al. reported on marine water sampling analysed for DP taken aboard a German research ship (Polarstern) when travelling from Greenland to the Antarctica. Along the Atlantic atmosphere, the highest concentration was observed at the east coast of Greenland and 97% ±9% were found in the particulate phase. DP concentrations found were in the range of below detection limit to 1.6 pg/L, with the highest value found between Greenland and Spitzbergen. As sampling in this area occurred during an ice melt period, this may have affected the results. Concentrations found in seawater close to Europe and North Africa were higher than concentrations in the southern hemisphere.

DP findings in sediment In total 8 publication were identified reporting DP concentrations in sediments. Sverko et al. reported in two publications (2008 and 2010) on DP concentrations in sediment in the Great Lakes Area. The concentrations found in Lake Ontario (downstream of Niagara Falls) are consistently higher (2.23-536 ng/g) than sediment concentrations found in Great Lakes upstream of Niagara Falls (e.g. in Lake Erie 0.061 - 3.62 ng/g), indicative of significant contribution by waste water released for the manufacturing plant. When analyzing sediment cores by slices a sedimentation rate could be determined (0.80 cm/year) and correlation with deposition year was made. Time dependent analysis shows that deposition started in 1971 reaching its maximum end of the 70ies with values found up to almost 1000 ng/g. Since then DP deposition declined steadily to levels of < 50 ng/g since the early 90ies. These findings were very much consistent with concentrations reported by Qui et al. (2007), showing a very similar deposition profile over time and those of Shen et al. (2010), analyzing sediment samples from the Great Lakes area. Klosterhaus et al. (2012) took samples form sediments in San Francisco Bay area analysing these for flame retardant content (including DP). All sediment samples contained detectable concentrations of DP. Total DP concentrations (syn- and anti-DP) ranged from 0.1 to 0.9 ng/g dw (median 0.2 ng/g dry) and were comparable to concentrations of HBCD in these sediments. Concentrations in San Francisco Bay sediments were generally one to three orders of magnitude lower than sediments in Lake Ontario, but were comparable to concentrations in Lakes Superior, Michigan, and Huron (all upstream from a manufacturing site), reported by Sverko et al. The fractional abundance of the syn-DP isomer (f syn ) was comparable to that of the technical mixture. In 2014 He et al. reported about their investigation in the Pearl River Delta in China where they also analysed DP in sediments. DPs (syn-and anti-DP) were detected in all sediment samples ranging from 0.08 to 19.4 ng/g dry weight with a mean value of 2.9 ng/g dw. The highest concentration was found at a site (19.4 ng/g dw) which was located nearing the largest industrial zones, Zhongtang Town. Relatively low concentrations were detected in the up-stream of the Dongjiang River being far from the urban areas and industrial activities, indicating that the discharge of industrial sewages could be the major source of DP to the river. The f anti value in the sediments was 0.77 ±0.09, which is close to the reported values in the DP technical product (f anti = 0.75 - 0.80), suggesting that stereoselective degradation of DP isomers was limited. Sediment samples analysed by Ma et al. (2011) in a Chinese river close to Harbin in the Northeast of China revealed a range of fluctuations, as the total DP concentration was 14 pg/g dw, 242 pg/g dw, and 115 pg/g dw in three different areas. The latter two values were found close to a waste water discharge site from the urban and industrial area, indicating that sediment concentration are also strongly influenced by such discharges. Findings by Wang et al. (2010) showed that sediments in the area of Huai’an in the Chinese province of Jiangsu, where a manufacturing plant for DP is located, had DP concentrations of (4.93 ± 4.34 ng/g) found in sediment from a nearby canal. The f syn value in most sediment samples were lower than the syn-DP fractional abundance (f syn ) value (0.40) for the commercial DP product manufactured at Anpon, suggesting a stereoselective depletion of syn-DP. However, as the syn-DP value in the surface sediment (0.24) was lower than the one in the bottom sediment (0.30) these results should be seen with caution and may be also attributable to changes in manufacturing over time and not necessarily to a depletion mechanism.

DP findings in soil Finding of DP in soil were reported in four publications, all reporting data from samples in China. Wang et al. (2010) reported in two publications his findings on DP concentrations found in soil in Huai’an city in Jiangsu Province, China, where Jiangsu Anpon Electrochemical Co., LTD, a manufacturer of DP, is located. Total DP levels reported ranged from 0.83 to 1200 ng/g dw with the highest values found in direct vicinity of the manufacturing plant. The ratios of anti- DP to syn-DP are relatively stable despite the great variation in DP levels and were not significantly different from the ratio of the technical material produced in Anpon. In the second publication, even higher concentrations were found 1490 ± 3580 ng/g dw. DP soil concentrations surrounding the facility decreased by an order of magnitude within 7.5 km. Yu et al. (2010) reported about DP concentrations in soil near e-waste recycling areas (Guiyu (GY) and Qingyuan (QY)).Guiyu is an established e-waste recycling town where 80% of the families have been involved in this industry, and where over 1 million tons of e-waste are dismantled and recycled annually. Qingyuan is a more recently reported e-waste recycling city, which holds over 1300 dismantling and recycling workshops and about 1.7 million tons of e-waste are dismantled and recycled there annually by over 80,000 workers. The mean concentrations of total DP in the e-waste recycling surrounding areas were 7.26 and 2.59 ng/g soil for QY and GY, respectively, whereas concentrations around the e-waste recycling workshops were as high as 3327 ng/g in QY. The results suggest that a significantly higher level of DP could be emitted as a result of inappropriate e-waste recycling activities in e-waste recycling areas in South China. The mean ratios of anti-DP to total DP (f anti) for different sampling areas ranged from 0.58 to 0.76 and showed no significant difference from the ratio for the technical DP products. Finally, Ma et al. (2011) reported about DP concentrations in soil collected from Harbin City, a typical northeastern Chinese urban region and found among the three soil samples, 10 pg/g dw, 12.5 pg/g dw, and 11.5 pg/g dw, respectively, with a mean concentration of 11.3 pg/g dw. Compared to the other reports, these values are several orders of magnitudes lower than values found close to manufacturing facilities and e-waste recycling sites, supporting the findings by Wang that soil DP concentrations decline steadily with distance from point sources to urban background levels being significantly lower.

DP findings in biota (fish, birds, and food) In total 15 publications reported DP concentrations in biota. Fish samples (lake trouts, 4-5 years of age, collected between 1979 and 2004) analysed from the Great Lakes by Ismail et al. (2009)showed DP ranges from 2.3 ±0.6 to 7.2 ±1.3 ng/g lipid (0.31 ±0.07 to 0.85 ±0.20 ng/g wet wt). The DP concentrations decreased significantly (p < 0.001) during the sampling period, with a half-life of 14 years. Houde et al. also assessed fish (yellow perch, northern pike, and muskellunge) in the St. Lawrence River between 2008 and 2012 and found DP concentrations ranging from 0.5 to 4.5 ng/g lw except for one highly contaminated muskellunge in Lake St-Louis (37.4 ng/g lw).No DP was found in yellow perch (lipid content 3.6 ±0.56%) and only in 36 and 45% of northern pike fish syn- or anti-DP could be detected (lipid content 7.5 ±1.2%) respectively. This indicates that lipid content in fish and position in the food web (yellow perch are typical prey fish and northern pike fish and muskellunge are typical predator fish in the St. Lawrence River food web) are dominant factors for accumulation of DP in fish. Shen et al. (2010) reported on Dechlorane Plus (DP) and other chlorinated flame retardants in sediment and fish from the Laurentian Great Lakes. Compared to mirex (480 - 540000 pg/g lipid) and total DP (61 - 2600 pg/g lipid), the pattern of relative concentrations is generally mirex > Dec 602 > DP > Dec 603 in lake trout from Lakes Superior and Huron; mirex ≈ Dec 602 > DP > Dec 603 in whitefish from Lake Erie. In Lake Ontario, the pattern is mirex > Dec 602 > DP > Dec 604 > Dec 603 in most samples except two lake trout and one whitefish that had the concentrations of Dec 604 slightly higher than those of DP, and the concentrations of Dec 602 were much greater (15 - 80 times) than those of DP. He et al. (2014) reported levels of DP found in mud carp, nile tilapia, and plecostomus being nd - 89.6 ng/g lw, nd - 189.3 ng/g lw, and nd - 52.3 ng/g lw, respectively. The f anti values in three fish species were significant lower than those in sediments and water, indicating a better enrichment of syn-DP in the three fish species, which was in line with other reports in fish species from other regions. The relatively low BSAF values of the three fish species suggest low bioaccumulation potential of DP isomers in aquatic organism (see section on bioaccumulation).DP isomers (syn- and anti-) were examined in the muscle, liver, and brain tissues of two bottom fish species (mud carp Cirrhinus molitorella and northern snakehead Channa argus) collected from an electronic waste recycling site, South China, by Zhang et al. (2011). Both syn- and anti-DP isomers were consistently detected in all the tissue samples, with the highest levels in the liver for northern snakehead (median values of 39.1 and 52.9 ng/g ww for syn-DP and anti-DP, respectively) and in the brain for mud carp (median values of 6.66 ng/g ww for syn-DP and 11.6 ng/g ww for anti-DP). Total DP levels (sum of syn- and anti-isomers) determined in the muscle of northern snakehead (with a median of 0.76 ng/g ww) were similar to those (0.17 ng/g ww on average) in the northern snakehead reported previously (Zhang et al., 2010). Levels of DP in the present fish were several (generally 1 - 4) orders of magnitude higher than those from Great Lakes (Ismail et al., 2009; Shen et al., 2011; Tomy et al., 2007), including those from waters downstream of a DP manufacturing plant in Niagara Falls, New York (Hoh et al., 2006). This result suggest that the aquatic species in the e-waste recycling site are exposed to elevated DP concentrations due to the primary e-waste recycling activities, and the e-waste site is another important source of DP, in addition to DP production facilities. The results demonstrate that the syn-DP is preferentially distributed in the liver of the investigated fish species, whereas anti-DP has high affinity to the brain. Kang et al. (2010) reported having measured Dechlorane Plus (DP) in five fish species collected in 2008 from 22 river sites across South Korea. The sites consisted of 15 urban-industrial areas, three rural-industrial areas, and four rural rivers. Both syn- and anti-DP isomer were consistently detected in all fish samples regardless of sampling sites and fish species. Concentrations of ΣDP isomers ranged from 0.61 to 126 ng/g lipid, with a mean concentration of 24.5 ng/g lipid. The mean ΣDP concentrations in the 15 urban sites (36.1 ±35.3 ng/g lipid) were approximately 25 times greater than those measured in the rural sites (1.4 ±1.0 ng/g lipid). The ΣDP concentrations in this study exceeded those determined in fish from the Great Lakes. DP exposure to fish was related to urbanization activity. Specific urban areas could be significant source areas of DP exposure, even in the absence of a local DP manufacturing facility. The anti-DP isomer was dominant in all samples. However, the mean f anti value for urban-industrial samples (0.67 ±0.060) was significantly lower than that of the technical DP standard (f anti = 0.75; p = 0.032). This observation supports that DP isomers may exhibit different bioaccumulation behaviors and that syn-DP isomer more easily accumulates in biota samples than anti-DP isomer does.

Besides DP concentrations in fish also concentrations in bird eggs were frequently assessed. Gauthier et al. (2007) investigated concentrations of Dechlorane Plus found in herring gull eggs, which correlated well with distance from a point source in Niagara Falls with decreasing concentration correlated with increasing distance from point source, supporting the distribution of DP via air. The highest concentration found was in herring gull eggs from Niagara river with 4.5 ng/g ww, close to a point source. Two years later (2009) the group published findings on samples that were collected in each of 15 years (1982, 1987, 1992, and 1995 - 2006) in late-April to early-May of each year. As Sum of DP concentrations were measured at all seven sites investigated for all years over the period, assessments of spatial distributions and temporal changes in herring gull eggs was possible. Furthermore, the presence of DP isomers in gull eggs indicated that this FR was accumulated in maternal gulls via the diet and transferred during ovogenesis to their eggs. DP-concentrations in hering gull eggs were shown to be in the range of 0.5 - 18 ng/g ww (samples measured from 1982 - 2006). A clear trend was seen for lower concentrations with distance from the point source at Niagara Falls. No variation of syn- and anti-isomer from commercial syn/anti ratio was seen, indicating no stereoselective bioaccumulation. Sun et al. (2012) sampled a total of 54 birds (Pycnonotus sinensis, Lanius schach, and Copsychus saularis) from seven sites in the Pearl River Delta (PRD), South China between September 2009 and May 2010. Four sites located in the middle of the PRD have highly developed industries and are considered as urban area, whereas the other three sites are characterized by agricultural activities, considered as rural area. Syn- and anti-DP were detected in all samples. The DP concentrations ranged from 3.9 to 930 ng/g lipid weight in muscle and from 7.0 to 1300 ng/g lipid weight in liver, respectively. Birds in urban sites had significantly higher concentrations of DP than in rural sites (mean, 300 vs 73 ng/g lw), suggesting that DP is linked to industrialization and urbanization. Klosterhaus et al. (2012) also investigated bird’s eggs in the San Francisco Bay area for flame retardant content. DP was detected in most San Francisco Bay wildlife samples, but at concentrations that were lower than HBCD and often approaching detection limits. The highest DP concentrations were detected in adult harbor seals (0.2–7 ng/g lw), but median concentrations among all wildlife samples were relatively similar (0.5 - 2 ng/g lw). The exception was harbor seal pups, in which DP was detected in less than half of the samples, and at concentrations ranging from below detection limits to 0.1 ng/g lw. Concentrations of DP in the San Francisco Bay cormorant eggs (0.9 – 1.1 ng/g lw) were generally more than an order of magnitude lower than concentrations in herring gull eggs in the Great Lakes and other parts of Canada (0.2 - 15 ng/g wet weight; sample-specific lipid weight concentrations not provided) and falcon eggs in Canada (38 - 65 ng/g lw), presumably due to closer proximity to the chemical manufacturing facility in the region. Concentrations of DP in Bay cormorant eggs were more comparable to stork and falcon eggs in Spain reported by Sverko et al. (2011).Zheng et al. (2014) reported on findings of Dechlorane Plus (DP) isomers. Chickens (Gallus gallus domesticus) were purchased from a local market in October 2011 and raised for seven months in a farmer’s yard, located in an e-waste recycling site in Qingyuan county, Guangdong province and surrounded by e-waste recycling workshops. Atmospheric particles, chicken food (mixture of rice, wheat and other types of grain) and soil samples were collected during chicken breeding in the yard. After the chickens were sacrificed in May 2012, 8 kinds of tissues (liver, muscle, heart, gonad, brain, lung, and fat, and kidney), chyme and digestive tract contents were collected and analyzed by GC-MS. DP could be found in chicken food, atmospheric particulates, and soil at median levels of 0.2, 1500, and 7600 ng/g dw (dry weight), respectively. The result confirmed that soil was the major source for DP in chicken. DP was detected in chyme, intestinal contents and feces at median levels of 7.6, 35, and 31 ng/g dw, respectively. The mass calculations of DP in chyme, intestinal contents and feces exhibited 52% absorption from chyme to intestinal contents and 50% absorption from intestinal contents to feces. No significant differences were found in DP levels between the intestinal contents and feces; while the DP levels in chyme were significantly lower than those in intestinal contents and feces. The f anti values ranged from 0.39 to 0.73 in chyme, intestinal contents, and feces. No significant differences in f anti were found among the three group samples, suggesting no stereo-selective absorption in gastrointestinal absorption for DP isomers. DP was detected in all tissues at median concentrations ranging from 0.92 to 10 ng/g ww (wet weight) or 17 to 140 ng/g lw (lipid weight). The results indicated that fat (accounting for 56%) was the most important DP reservoir, followed by liver (12%) and gonad (12%). Similarity in ratio of anti-Cl11-DP to anti-DP between soil and chicken tissues implied the dietary absorption of anti-Cl11-DP rather than in vivo dechlorination of DP in chicken. Venier et al. (2010) analysed DP (as the sum of the two isomers, syn and anti) in 15 blood samples of nestling bald eagles from the Great Lakes region. Following workup the plasma samples were quantitatively analysed by GC/MS techniques. DP was only detected in six out of fifteen samples at an average concentration of 0.19 ±0.10 ng/g ww (median 0.09 ng/g ww). This flame retardant was also reported in herring gulls eggs from the Laurentian Great Lakes at levels ranging from 1.7 to 4.5 ng/g ww (Gauthier et al., 2007). The levels in these bald eagle samples seem to be much lower than in gull eggs, probably because of differences in the diet of these two species. Munoz-Arnanz et al. (2011) analysed 33 failed eggs of white stork, obtained from two different colonies located in Doñana National Park (south-western Spain) and Madrid (central Spain) for DP content. Dechlorane Plus was found in all the eggs analyzed. The average concentration for total DP in white storks from DNP was 105 pg/g ww (median value 84.6 pg/g), ranging between 2.58 and 468 pg/g. The levels found for the Madrid colony were significantly higher, with an average concentration of 401 pg/g ww (median value 306 pg/g) for total DP ranging from 56.8 to 1400 pg/g. Higher levels in urban than in rural environments were a priori expected. In the urban colony, a 4-fold higher DP average concentration was observed. DP concentrations in white storks were well below values found in herring gull (Larus argentatus) eggs from the Laurentian Great Lakes. The fact that herring gulls are an aquatic species and white storks, a mainly terrestrial species may partially account for the DP concentration differences observed. Moreover, the colonies from the Laurentian Great Lakes are geographically located in the proximity of a DP manufacturing plant and therefore more likely exposed to higher environmental levels of DP. Neither the retro-Diels–Alder product 1,5-DPMA nor the dehalogenation product anti-[DP-2Cl] were detected above their quantification limits in any sample. The other DP dehalogenation product investigated in this study, anti-[DP-1Cl], was found in about 10% of the samples from each colony, with an average concentrations of 2.35 pg/g in DNP and 0.548 pg/g in Madrid. Both stereoisomers were found with a fractional abundance similar to that reported for the technical product. Guerra et al. (2011) investigated peregrine falcon (falco peregrinus) eggs that failed to hatch, collected in Canada at the Great Lakes and in Spain (Central and Coastal area) for chlorinated flame retardant concentrations including DP. Concentrations of Mirex, Dechlorane (Dec) Plus (DP), Dec 602, Dec 603, and Dec 604 were significantly higher in peregrine falcon (Falco peregrinus) eggs from Canada than Spain, with the former having the only measurable concentrations of the dechlorinated DP products. Compared to the eggs laid by Spanish peregrines with a terrestrial diet, the peregrine eggs from Canada had significantly higher in ovo concentrations of Mirex, Σ DP, Dec 602, 603, and 604, the only detectable concentrations of aCI10DP and aCI11DP, and lower f anti values. DP concentrations found were (as median values) 0.6 ng/g lw in Spanish peregrines (terrestrial area), 2.3 ng/g lw in Spanish peregrines (coastal area), 43 ng/g lw in Canadian peregrines (terrestrial area) and 64 ng/g lw in Canadian peregrines (aquatic area). The geographical differences in the measured in ovo concentrations between Canada and Spain reflect local exposure of the adult peregrines on the breeding grounds during egg laying, likely differences in the diet of the adult birds, the production of DP on the Niagara River in Canada, and the greater use of Mirex and dechloranes as flame retardants in North America than Europe.

Analysis of food samples is an indirect detection in biota and two publications reported on such assessments. Kim et al. (2014) analysed a market basket collected in Korea, analyzing the food for chlorinated flame retardants incl. DP. The mean ΣDPs ranged from ND to 169.85 pg/g wet weight (ww).The highest mean concentration of ΣDPs was detected in bovine liver with 169.85 pg/g ww, followed by Spanish mackerel, oyster, and dried anchovy with 134.50, 80.78, and 77.79 pg/g ww, respectively. DP was found in almost every foodstuff except of onions, in which no DP was detected. Whereas DP concentration were found being in the lower range for vegetable and fruits (2.22 - 4.02 pg/g wet weight) concentrations in meat and fish were seen at the upper end (9.84 - 169.85 pg/g wet weight and 0.57 - 134.5 pg/g wet weight), respectively. Based on dietary habits of Koreans, an estimated dietary daily intake of 11.2 ng/day was estimated for Koreans where grain was the most contributed food group to dietary daily intake of DP for Korean population. Kakimoto et al. (2012) published their findings on fish samples purchased from Japanese markets which were analyzed for Dechlorane Plus (DP)(syn-, anti-), poly-brominated diphenyl ether (PBDE), and hexabromocyclododecane (HBCD)(a, c). DP was detected in 18 out of 20 samples and ΣDP concentrations were <0.2 to 14.2 pg/g wet wt. PBDE was detected in all samples and concentrations were between 2.2 and 878 pg/g wet wt for ΣPBDE. HBCD was detected in 18/20 samples and the ΣHBCD concentrations were <0.02 - 21.9 ng/g wet wt. In this study, the f anti value (0.56 - 0.72) was rarely different from that of the commercial product. Concentrations of ΣDP were approximately one hundredth of those of ΣPBDE and one thousandth of those of ΣHBCD.

In two review articles by Xian et al. (2011) and Sverko et al. (2011) environmental findings of DP were summarized (that were available until 2010) as described above. Both groups summarized the findings with respect to biomagnification/bioaccumulation as contradictory. The high concentration findings in the environment are attributable to point sources such as the two manufacturing plants worldwide and e-waste recycling sites whereas concentrations in urban areas are significantly lower and even lower in rural areas. This is seen consistently in air, water, sediment and soil samples but also in biota samples analysed. Xian et al. stated that results on the possible biomagnifications of DP in aquatic biota from North America and China seemed contradictory. Further, there are no data yet on biomagnification in terrestrial biota. On a lipid weight basis, there is no clear evidence of a higher DP level in humans when compared with terrestrial or aquatic biota. Sverko et al. similarly stated that available data suggest that food web biomagnification may be occurring in some cases for DP; however, there is substantial variability between the BMF and TMF data which may be a result of species-specific differences in biotransformation, limited sample size or a violation of the steady-state assumption required for calculating BMFs and TMFs; in other words, the chemical concentrations in the food web are not approximating steady-state conditions. With only limited data available so far, the biomagnification of DP in aquatic biota has not been conclusively demonstrated; species differences do exist depending on predator/prey set assessed, with some showing biomagnification and other not. The results from Möller et al. show, that DP is able to transport mainly bound to airborne particles over distances, as DP concentrations, even at very low levels, could be detected in the Atlantic (air and water phase) in the Northern and to an even lesser extent in the Southern hemisphere.

In summary DP is found in all environmental compartments (air, water, sediment and soil) but in rather low concentrations when compared to other flame retardant such as Mirex or brominated flame retardants (orders of magnitudes lower). High peak concentrations are found close to manufacturing sites for DP and e-waste recycling sites in China. Besides those, low levels can be found in urban and highly industrialized areas and even lower concentration, close to quantification limits, in rural areas. Although in some publications a difference in syn- and anti-DP accumulation is postulated, the most studies do not support this hypothesis. The slight variations seen may be due to the fact that syn/anti-DP ratios are different in the two manufacturing plants on one hand and on the other hand variations over time in the manufacturing plants may have existed due to optimization of production processes. Also, thermal stress in e-waste recycling sites (plastic is incinerated there) may alter the syn/anti-DP ratio leading to variations in findings. Only the results from Möller et al. do indicate, that the syn/anti-DP ratio may change upon exposure to UV-light in air and that the syn-isomer is more stable to UV-light than the anti-isomer. As transport via air is the dominant route for DP distribution, this also may have affected some findings, especially at concentration found close to quantification limits. However, in other compartments (water, sediment, soil, biota) the syn/anti-DP ratio appears to be not significantly affected.