الفهرس 
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Abstract
The present study determined the quality control, recovery and the accuracy of the method analysis used for focus on the monitoring of certain contaminant levels of dioxins, furans and dl-PCBs in raw cow milk, rations and their products collected from certain Egyptian farms i.e. Qaliubiya, Sharkia, Monoufia, Damietta, Kafr El-Sheikh, Gharbiya, Ismailia, Port Said, Noubaria (Beheira), Fayoum and Beni Sweaf representing the eastern, western and middle Egypt consequently. Then continuous by animal feed and different varieties of processed cow liquid milk samples from the big markets in terms of geographical distribution in which represents the same location farms. Thereafter, to compare these levels with the most recent published international studies such as EU standards in this aspect and finally to estimate there dietary intake (EDI) due to their acceptable daily intake (ADI).
A total number of samples had been collected; firstly of 59 animal feed and 35 raw cow milk samples from farms mentioned above; secondly from big markets which included of 92 animal feed and 106 different varieties of processed cow liquid milk samples; including full cream milk (69), half cream milk (22) and skim milk (15). The analyses were included the 17 toxic 2,3,7,8-chlorinated dibenzo-p-dioxins and furans (PCDDs/PCDFs) as well as 12 dioxin like PCBs (dl-PCBs). The animal feed samples were consequently collected as a whole and individual feed including hay, cereals and other farinaceous feed, premixes and mixed feeds.
For qualitative and quantitative determination of dioxins/furans and dl-PCBs, Gas chromatography/High Resolution Mass Spectroscopy (GC/HRMS) was used.
The results obtained from the monitoring under study as follows:-
Firstly from farms, the obtained results of dioxins (PCDD/Fs) and dl-PCBs revealed that all of cow milk and animal feed samples contained certain levels of PCDD/Fs and dl-PCBs congeners, the dioxins contaminated samples which exceeded the maximum permissible levels (EC, 2006a and b) were up to (45.7 and 8.5%) in raw milk and animal feed, respectively. Also for dl-PCBs, only (3%) of raw milk samples were exceeded the EU limits.
Raw cow milk and animal feeds from kafr El-Zayat farm (Gharbiya governorate) which represent rural areas and nearby industrial zones were recorded the highest levels of (PCDD/Fs and dl-PCBs) as a total-TEQ contamination in all farms; hence the cow milk, animal feed [vegetable oils and clover] samples were at the maximum levels up to 14.60 pgTEQ.g-1 fat weight (FW), 1.81 and 1.48 pgTEQ.g-1 dry weight (DW), respectively in which exceed the EU maximum limits in food of 6 pg WHO-TEQ g-1 fat weight and the animal feed samples were exceed the EU Maximum limits of 1.25 pgWHO-TEQg-1 dry weight.
On the other hand, raw cow milk and animal feeds from El-Noubaria farm (Beheira governorate), sited in the modern reclaimed lands near urban areas were recorded the lowest levels of (PCDD/Fs and dl-PCBs) as a total-TEQ contamination in all farms; hence the cow milk was 1.48 pg TEQ g-1 fw and the animal feed sample as [soybean-cereals] was 0.09 pg TEQ g-1 dw, there were below the EU limits, respectively.
Secondly from markets, was observed that, the dioxins contaminated samples which exceeded the European maximum permissible levels (EC, 2006a and b) were up to (37.7 and 9%) in processed milk and animal feed, respectively. While for dl-PCBs, only (1%) of processed milk samples were exceeded the EU limits.
In general, the mean concentration of dioxins and dl-PCBs in whole processed cow milk (expressed as WHO-TEQ) were estimated for a mean dioxins (TEQ) concentration of 2.87 ± 1.99 pg TEQ g-1 fw ranged between (0.02 – 9.91 pg TEQ g-1 fw) and a mean dl-PCBs (TEQ) concentration of 0.46 ±0.42 pg TEQ g-1 fw ranged between (0.003 – 3.31 pg TEQ g-1 fw). Whilst as individual type of processed milk, the mean dioxins concentration were (2.97±1.33), (4.51±2.36) pg TEQ g-1 fw and (0.06±0.03) pg TEQ g-1 fresh weight in full cream, half cream and skim milk samples, respectively. Also the mean dl-PCBs were (0.48±0.38), (0.71±0.43) pg TEQ g-1 fat weight and (0.01±0.01) pg TEQ g-1 fresh weight in full cream, half cream and skim milk samples, respectively. In the context of total TEQ (dioxin and dl-PCBs), the sum of furan (TEQ) was the predominant group with contribution 51.8 and 62.87%; followed by the sum of dioxin (TEQ) with contribution 34.4 and 28.31%; followed by the sum of non-ortho PCBs (TEQ) with contribution 12.37 and 6.72% and then the sum of mono-ortho PCBs (TEQ) with contribution 1.44 and 2.1% in processed cow milk and animal feed, respectively. The samples contained more furans than dioxins indicating a discrete influence of thermal processes.
The results obtained from the estimation of daily intake (EDI) study of PCDDs/PCDFs and dl-PCBs in milk by the food consumption data (177.4 fresh weight g/day) for Egypt, according the food balance sheet, FAO,(2011) and an average body weight of 60 kg as used by the WHO, (2005) were as follows :-
Firstly, the obtained results of dioxins estimation revealed that the total dietary intake of (PCDD/Fs+ dl-PCBs) from the consumption of milk was estimated to be 0.002, 1.79 and 0.35 pg WHO-TEQ/kg body weight/day as minimum, maximum and mean, respectively. Regarding to EDI, Our results proved that the current mean daily intake of PCDDs, PCDFs and dl-PCBs by processed (UHT) milk consumption was in a better range from the tolerable daily intake (TDI) proposed by the WHO (1– 4) pg WHO-TEQ/kg body weight/day (Van Leeuwen and Younes, 2000). Therefore, Egyptian milk in our investigated study is relatively safe which represent 0.35 pg WHO-TEQ kg-1 body weight day-1 with ratio (8.6%) as the mean intake from dioxins and dl-PCBs, due to the low daily intake compared to the acceptable daily intake (ADI).
The results obtained from the minimization of PCDD/Fs and dl-PCBs contaminated full cream and skim milk through advanced reduction process treatment by using Laccase enzyme, Rhus vernicifera as follows:-
Minimization of PCDD/Fs and dl-PCBs contaminated full cream and skim milk was studied through advanced reduction process treatment by using laccase enzyme, Rhus vernicifera with different concentration units (3.6, 7.2, and 10.8U) under contact time of 2hr (30°C shaking water batch at 150 rpm). Also, the effect of the treatment process (reduction) milk constituents has been studied by analyzing the contents of total protein, fat and pH before and after these treatments.
In general, the degradation of PCDD/Fs and dl-PCBs were markedly observed in full cream milk samples, where the highest degradation were obtained using 10.8U of laccase in which a total of 21 and 23% reduction for PCDD/Fs and dl-PCBs, respectively. On the other hand, very limited reduction was occurred in skim milk samples, even when using higher laccase conc. of 10.8 U, whereas reduced as a total of 6 and 14% for PCDD/Fs and dl-PCBs, respectively. It was also revealed that the degradation of dl-PCBs was higher than PCDD/Fs depends on their physico-chemical properties and their metabolic behavior. After measurements of fat contents it was observed that, fat content in the studied full cream milk wasn’t affected by the presence of laccase enzyme at its three different concentration units in which were reduced of 7.62, 7.5, and 7.25%, respectively. Also, it was observed that there were no effects obtained on the total protein contents and pH of milk. The highest degradation efficiency of dioxin and dl-PCBs congeners, observed for 1,2,3,7,8,9-HxCDD of 28 and 8%, and PCB118 of 49 and 19% in full cream milk and skim milk, respectively. Whereas, the lowest degradation efficiency of dioxin and dl-PCBs congeners, was obtained for 2,3,7,8-TCDF of 16 and 6%, and PCB81 of 12 and 8% in full cream milk and skim milk, respectively. In general, it was observed that the ability of laccase to reduce the PCDD/Fs and dl-PCBs in full cream milk is higher than in skim milk. This reduction might be attributed to the active high surface area of laccase enzyme in full cream milk, which contains a high fat that may lead to an attraction force between the enzyme and contaminants.
In full cream and skim milk samples treated by laccase, the reduction efficiency (RE%) for dl-PCBs congeners pattern was higher than dioxins congeners under the same condition of laccase concentration and contact time. This is may be due to its steric molecular structure of dl-PCBs (planar or co-planar PCBs), where the effect of steric structure increasing its reduction. In addition, the high partition coefficient (Log Kow) of dl-PCBs may play a role with this steric structure for their reduction efficiency than others in dioxins (hetero cycle compounds). Finally, it can say or suggest that fat has a close association by increasing enzyme effectiveness in the oxidation and reduction process of these compounds.
Thus, it can recommend to use laccase enzyme to mitigate the persistent organic pollutants (dioxins and dl-PCBs) from contaminated milk products to produce safe food products.