# Assessment of Dietary Exposure and Risk of DDT Concerning Freshwater Fish Aquaculture
## 1 Introduction  
Fish is one of the essential protein sources for mankind with several advantageous nutritional effects. Due to its high content of omega-3 fatty acids, it has a beneficial effect on the cardiovascular system of the body. It also contains significant amounts of vitamins B12 and D [1, 2]. Among others, because of its mentioned nutrient composition, the consumption of fish is part of a balanced, varied human diet. According to the latest available European data, the annual fish consumption in Hungary is 5.6 kg/capita [3]. This value lags significantly behind most of the countries in the European Union, which puts Hungary at the bottom of the list in terms of fish consumption. Based on EUMOFA (European Market Observatory for Fisheries and Aquaculture Products) data for 2018, Hungarians spend 14 euros per year on fish and seafood, which is about one-eighth of the EU average [3]. Although Hungary is below the average considering total fish consumption, it leads the EU list in terms of carp consumption, with 1.2 kg annually [4]. In our preliminary research, the fish consumption habits of the Hungarian population were investigated in general, with a representative, questionnaire-based consumer survey, between 21 August 2018 and 12 September2018, involving 1002 people. The sample was representative of the adult Hungarian population by gender, age and region of residence, based on the data of the 2016 micro-census [5]. As a result of the survey, five consumer groups were identified by hierarchical cluster analysis based on the frequency and the amount of carp consumption. Three clusters out of five are worth further investigating if they are exposed to any risk of freshwater fish consumption because oftheir consumption patterns. The group of \"The fishermen\" is mostly men over the age of 40, consuming carp more times than the average in larger quantities (27.2 times a year, 225.01 g/occasion--6.12 kg/year). The cluster of \"the hearty eaters\" is the second potentially exposed group. Although they eat fish less frequently, the amount of fish consumed on one occasion is remarkably high (5.89 times a year, 309.80 g/occasion--1.82 kg/year). The last group is the \"The carp fanatics\", mostly over 60 years old men. In their case, the frequency of carp consumption is remarkably high, almost ten times the average (109.34 times a year, 245.64 g/occasion--26.86 kg/year) [6]. The topic of heavy metal accumulation in marine fish is a widely studied research area [7; 8; 9]. In contrast, it is less known that the extreme consumption of freshwater fish may also have risky effects, regarding different groups of chemical compounds. Significant amounts of pesticides may accumulate in freshwater fish meat due to the pesticide contamination of the fishponds [10; 11]. Fish--especially fatty fish species--can pose a health risk due to the accumulation of heavy metal contamination (such as arsenic, mercury, or cadmium) [12; 13] and the presence of persistent organic pollutants (POPs) [14] as well. The fat content of pond-cultured carp may vary between 4-5% or even 10-23% depending on whether they are fed and if so, with what type of feed [15], therefore, carp could be considered as medium/high-fat fish [16]. Within the framework of a comprehensive survey carried out in the HappyFish project (NVKP_16-1-2016-0023 project funded by the National Competitiveness and Excellence Programme), the pesticide content of the water and the fish in Hungarian fishponds were analyzed. Based on the results, 21 of the 420 tested pesticides were present in detectable quantities in the fish samples, in 0.01-0.05 mg/kg amounts. One of the most common contaminants in Hungarian fishponds is the organochlorine insecticide DDT (dichloro-diphenyl-trichloroethane). DDT is a highly persistent, high-efficiency insecticide that was widely-used globally in the 20 th century. Due to its neurotoxic and possibly carcinogenic effect (compound belonging to IARC group 2A), it has been banned in Hungary since 1968 [17; 18; 19].