## 4 Discussion
In the analysis of cultured shrimp in Bangladesh, the detection of chloramphenicol and nitrofuran metabolite residues revealed a violation ratio of 8.37% (118/1409) in 2008, 8.16% (182/2230) in 2009, and 5.81% (122/2098) in 2009 [24]. In addition, in the Canadian Total Diet Study from 1994 to 2004, the detection of MG, LMG, and nitrofuran metabolite residues revealed a violation ratio of 20.0% (6/30) [25]. In Ireland, exposure to nitrofuran residues was assessed from 2009 to 2010, which revealed a violation ratio of 5.68% (5/88) in the detection of SEM residues [26]. However, in the aforementioned reports, only two classes of nitrofuran metabolites and chloramphenicol or three classes of MG, LMG, and nitrofuran metabolites were detected. Our present findings differ from those of TFDA surveys. In reports in recent years, the violation ratio of banned veterinary drug residues in shrimp samples was 0% in 2013 (0/20) [27] and 0% in 2014 (0/20) [28]. These differences are partially accounted for by varying sample sizes. In addition, the samples collected in this study were obtained from shrimp production areas in Taiwan, whereas the samples collected by the TFDA may have been imported shrimp. Therefore, several categories of banned veterinary drugs in Taiwanese shrimp were appropriately detected in the present study. In the present investigation, quinolone residues (3/53) were detected with a higher violation ratio than chloramphenicol (1/53) in aquaculture shrimp. Our study revealed that quinolones were the predominant compounds in the aquacultured shrimp samples in Taiwan, which was similar to the results of a survey conducted in China [29], Vietnam [30; 31], and Thailand [31] following intensive use in aquaculture to treat bacterial infections, which polluted aquatic habitats and had adverse effects on the health of freshwater organisms. Quinolones were detected in 8.70% (2/23) and 7.14% (1/14) of whiteleg and giant river shrimp samples, respectively. In all shrimp samples, the predominant residue was flumequine at 3.77% (2/53), followed by enrofloxacin at 1.89% (1/53). The results of the present study are similar to those of the survey conducted by the TFDA. Compared with a report of the TFDA in 2012, the violation ratio of quinolone residues in shrimp samples was 4.0% in 25 samples, which was positive with flumequine at 21.0 ng/g in one shrimp sample [32]. From the data available, we concluded that flumequine continues to be used as a growth promoter and prophylactic agent in aquatic products because of its affordability and effectiveness. Other surveys in Asia [31; 33] have reported that flumequine has been the most widely used synthetic antibiotic in aquaculture, especially because of its relative stability to resist bacterial degradation in water and sediments. In addition, flumequine residues were detected in trace amounts; only a concentration of 1.01-1.52 ng/g or higher triggers action by the TFDA (withdrawal of the product and issuance of an alert). The results of the surveys reviewed herein indicate that the Taiwanese population is exposed to trace amounts of flumequine that do not pose an immediate risk to health through the consumption of shrimp. Therefore, Taiwan's regulatory authorities and producers should continually monitor aquatic products and prevent sources of contamination, ensuring the chemical safety of commercially available foods. Parameter guidelines indicate how the risk to organisms such as humans can be assessed by stipulating criteria related to the ADI, hazard quotients, provisional tolerable weekly intake, and excess cancer risk [6; 34; 35]. Guidelines for the ADI, such as those formulated by the FAO and WHO, facilitate the assessment of risks to organisms, including humans [6]. The ADI is a single value, however, and eating habit and consumption rate differences are not considered in its calculation [36; 37]. The JECFA [38] and US EPA [39] have proposed a new and highly accurate measure for the estimation of chronic dietary intake: the EDI.