MONITORING OF GENETICALLY MODIFIED FOOD ON THE CZECH FOOD MARKET AND A CROSS-COUNTRY COMPARISON

The presence of genetically modifi ed organisms (GMOs) was analysed in food samples from the Czech food markets. Four different types of food samples (soya beans, soya bean products, maize fl our, and rice) were collected at twelve places in four terms in the years 2008–2013. It represents a total 1152 food samples. Soya and maize were chosen, because these are the major transgenic crops grown worldwide. Increased cultivation of GM rice in China, India, Indonesia, and the Philippines has been observed. Polymerase chain reaction-based methods were applied to detect GMOs. GMOs were detected in 107 samples (9.3%). The results show that in food from the Czech food market GMOs mainly in maize fl our and rice were found. GM maize was detected in 63 (21.9%) maize fl our samples. Maize lines MON810, NK603, and Bt176 were detected in 14 (22%), 9 (14%), and 1 (1.6%) maize fl our samples, respectively. Unauthorised GM rice was detected in 39 (13.5%) rice samples. Unauthorised rice Bt63 was detected in one sample of rice. Roundup Ready soya was detected in 4 (1.4%) soya bean samples and in 1 (0.35%) soya product sample. These results were compared with results of the world ́s studies.

Genetic engineering and genetic modifi cation are terms that relate to the manipulation of an organism's genes through recombinant DNA technology.Genetically modifi ed (GM) crops have been modifi ed through the introduction of new agronomic traits or suppression of constituent genes, which code for e.g.disease/pest resistance, herbicide tolerance, increase of nutritional value (QAIM, 2009;RONALD, 2011).
GM crops have set a precedent in that the biotech area has grown impressively every single year for the past 19 years, with a remarkable 100-fold increase since the commercialization began in 1996.Thus, GM crops are considered as the fastest adopted crop technology in the history of modern agriculture.A total of 18 million farmers planted biotech crops in 28 countries, wherein over 94.1% were small and resource-poor farmers from developing countries.Of the 28 countries planting biotech crops in 2014, 19 countries planted 50 000 hectares or more GM crops.These mega-countries include' e.g. the USA, Brazil, Argentina, India, Canada, China, Mexico, and Spain.To provide a global perspective of the status of GM crops, the global adoption rates as a percentage of the respective global areas of the four principal crops are -soya bean (82%), cotton (68%), maize (30%), and canola (25%) (JAMES, 2014).
GM crops are involved in the production of a variety of GM food.The release and consumption of GM food can raise questions about health and environmental safety.Available impact studies of insect-resistant and herbicide-tolerant crops show that these technologies are benefi cial to farmers and consumers, as well as have positive effects on the environment and human health.GM crops can contribute signifi cantly to global food security and poverty reduction.Nonetheless, widespread public reservations have led to a complex system of regulations.Overregulation has become a real threat for the further development and use of GM crops.The costs in terms of foregone benefi ts may be large, especially for developing countries.Economics research has an important role to play in designing effi cient regulatory mechanisms and agricultural innovation systems (QAIM, 2009;RAVEN, 2014).
The use of GMOs raises several ethical issues.There are increased consumer concerns over the use of GMOs in food products, mainly in the European Union (EU) countries, while in North America, the technology is more accepted.In order to guarantee consumers' freedom of choice, the use of GMOs and GMOs derived products in the food chain is subject to precise regulations in several countries.The labelling of food and a derived product is mandatory in the EU with a threshold of 0.9% (KYROVA et al., 2010).The above-mentioned facts clearly demonstrate the need for an offi cial control of food products by the Czech regulatory and inspection authorities (e.g.Czech Agriculture and Food Inspection Authority).
The objective of this study was to determine qualitatively the occurrence of products derived from genetically modifi ed soya, maize, and rice in foods sold commercially in the Czech Republic.Soya and maize were chosen, because these are the major transgenic crops grown world-wide.Increased cultivation of GM rice in China, India, Indonesia, and the Philippines has been observed (GMO COMPASS, 2015).The study was realised by project of the Monitoring the environmental impact on population health of the Czech Republic, subsystem 4: Health effects and risks of human dietary exposure to contaminants.The occurrence data of unauthorised and authorised GMO in foodstuffs are very important and serve as a basis for public health protection and promotion.

Collection and sampling procedures
Four types of food samples: soya beans, soya products (soya bean meal, dehydrated textured soya bean protein), maize fl our (fi ne, medium-coarse, coarse), and rice (long grain rice, medium grain rice, short grain rice, basmati rice) were collected in four sampling terms in 12 regions of the Czech Republic in years 2008-2013.A total of 1152 food samples were gathered.None of these samples were labelled as containing or consisting of GMOs.

DNA extraction
The samples were ground in an electric mill.DNA was extracted from the sample (50 mg) using commercial kit PowerPlant ® Pro DNA Isolation Kit (MoBio laboratories, Carlsbad, USA) according to the producer´s recommendation.DNA from reference materials was extracted from 50 mg material using the same method.The DNA quantity and purity were estimated by measuring the absorbance at 260 nm and at 280 nm by means of a Helios Gamma spectrophotometer (Thermo Spectronic, Cambridge, UK).
Certifi ed reference materials (CRM) from the Institute for Reference Materials and Measurements (IRMM, Geel, Belgium) were acquired from Fluka (Buchs, Switzerland) and used for validation of the method for the detection of RRS (IRMM 410) and maize events Bt11 (IRMM 412), MON810 (IRMM 413), Bt176 (IRMM 411).For maize T25, GA21, StarLink, DAS1507, and rice Bt63 the genomic DNA from GeneScan Europe (Freiburg, Germany) was used.As positive control for maize Bt10, maize fl our from EURL (European Reference Laboratory for GM Food and Feed, Ispra, Italy) was used.

Results and discussion
An occurrence of GM soya, GM maize, and GM rice in foods is presented in Table 2. Figure shows the number of positive samples in different years.In total, GMOs were detected in 107 food samples (9.3%).The results show that GMOs were found rather in maize fl our and rice than in soya bean and soya products in foods from the Czech food market.GM maize was detected in 63 (21.9%) maize fl our samples.Maize lines MON810, NK603, and Bt176 were detected in 14 (22%), 9 (14%), and 1 (1.6%) maize fl our samples, respectively.Unauthorised GM rice was detected in 39 (13.5%) rice samples.Unauthorised rice Bt63 was detected in one sample of rice.Further not specifi ed genetic modifi cations were found in 39 positive samples of maize fl our and 38 positive samples of rice by using identifi cation PCR method.RRS was detected in 4 (1.4%) soya bean samples and in 1 (0.35%) soya product sample.In our previous study, soya beans, soya products, maize fl our, and rice were collected in the Czech Republic during the years 2002-2007.RRS was detected in 14 (4.9%) samples of soya bean out of 288 and in 88 (30.5%) soya products out of 288 samples.GM maize was detected in 5 (1.7%) of 288 samples.Maize lines MON810, Bt176, and StarLink were detected in the maize samples.GM rice was detected in 2 (1.9%) samples out of 102 (KYROVA et al., 2010).
Our results were compared with the results from recent studies in Europe and in the world.
Several countries have conducted survey to monitor the presence of GMOs in foods.For example, 251 soya food samples were bought from the Hungarian food market.According to the results, 38% of the examined samples indicated presence of RRS in soya-containing foods (UJHELYI et al., 2008).Food testing for the presence of GMOs was also realised in Croatia.Among the most common analysed food samples were soya bean and maize as well as their products.During 2004-2007 2797 samples were analysed and 139 (4.97%) contained GMO.The most positive results were found in samples like spice mixtures and other raw materials (based on soya bean) for further processing in the food industry (meat, bakery industry) originating from import (CATTUNAR et al., 2011).

Acta Alimentaria 47, 2018
Two types of maize fl our and four types of soya products were qualitatively analysed during 2013 in Romania.The presence of GMO both in a maize sample and a soya sample was found (CURTICĂPEAN & CURTICĂPEAN, 2014).
A total of 119 food maize samples were acquired in Portugal local supermarkets.The overall results of GMO screening were 30% for 35S promoter, 10% for NOS terminator, and 25% for identifi ed events.The most frequently detected events were MON810, TC1507, and NK603, with one sample containing GA21 (FERNANDES et al., 2014).
In a Serbian study, the presence of genetic modifi cations was analysed in a total of 100 samples of non-labelled vegetarian and healthy food products.The basic raw materials in the tested samples were maize, soya, and/or rice.The 35S promoter was detected in 8 (8%) samples.None of the analysed samples contained GM maize and GM rice (ZDJELAR et al., 2013).
GM maize and GM soya in processed food products and feed were found in Turkish studies.Current legislation has restricted the penetration of GM maize into the Turkish food industry but not eliminated it, and the proliferation of different GM events is making monitoring increasingly complex.These results indicate that labelling requirements are not being followed in some cases (OZGEN ARUN et al., 2013;TURKEC et al., 2016).
In a Jordanian study it was investigated at what level Jordanian consumers are exposed to GM foods.DNA was extracted from 200 food and 80 feed samples bought in Jordanian markets and investigated by PCR.Fifteen (5.4%) food and feed samples were found positive for maize Bt176 or RRS genes.The GM elements were detected in more than 62.5% with less than 1% modifi cation, compared to less than 37.5% containing more than 1% GM (HERZALLAH, 2012).
There are no legislations on GM labelling and cultivation of GM crops in Tunisia.The present study aims to check the status of GMO on the Tunisian market.Three hundred and sixty-fi ve samples were collected.Seven food and feed products showed signs of RRS (1.9%), MON810 (2.1%), and Bt11 (1.6%).The results demonstrate for the fi rst time the presence of GMO in Tunisian markets (CHAOUACHI et al., 2013).
In opposition to these fi ndings, Brazilian authors did not detect transgenic maize in commercialised foods from Brazil along the years of 2002-2007(BRANQUINHO et al., 2010;;DINON et al., 2010).BRANQUINHO and co-workers (2010) analysed 240 samples of soyaderived foodstuffs from 2004 to 2007.In food containing soya bean, 68 (28.3%) were shown to contain GM soya bean.

Conclusions
Foodstuffs on the Czech and world market contained authorised and unauthorised GMOs.Consumers have the possibility to choose between GM or non-GM foodstuffs.They expect food to be safe and healthy.There is no information about adverse effect on human health of authorised GM foodstuffs.The further study of monitoring should mainly be focused on detection and identifi cation of unauthorised GMOs, e.g.rice and papaya.*

Table 1 .
List of primers and methods used for GMO screening and identifi cation tests

Table 2 .
Occurrence of GMOs in foods in 2008-2013 n: number of samples; n+: number of positive samples; % n+: percent of positive samples