**2.3. Metal residues in organic animal products**

mesophilic n = 218; for coliform n = 101) were higher than conventional milk (for mesophilic n = 1168; for coliform n = 473) [21]. In one of the two different studies conducted in USA, no difference was present between organic and conventional (sum of grazing and not grazing) milk regarding SSC [22], and in the other study, very little difference was determined in terms of SSC and standard plate count [23]. Although no difference was found between organic and conventional milk samples concerning the diversity of spore forming aerobic bacteria, bacteria isolated from milk obtained from conventional farms were found to be more resistant to heat, and *B. cereus* organisms were abundant in organic milk, whereas *Ureibacillus thermosphaericus* were abundant in conventional milk. It has been suggested that this situation may be related to dietary strategy in the farm [24], and restricted silage use in organic ruminant breeding may reduce the bacterial

Mycotoxins are toxic molecules, which are synthesized by molds growing on plants. These highly toxic and heat-resistant toxins are transferred to animals with plants, and to humans with animal products through the food chain. Among the mycotoxins, particularly aflatoxin (AFL), ochratoxin (OTA), fumonisins, deoxynivalenol (DON), patulin and zearalenone are the most important mycotoxins for public health. Mycotoxin contamination in animal products is lower than in those from plant origin. Studies comparing the organic and conventional animal

In Latvia, mold strains belonging to 15 genera were identified in the raw milk samples collected from organic farms between December 2011 and November 2012. Among these strains, the most common ones were *Absidia, Aspergillus, Apophysomyces, Mucor, Penicillium* and *Rhizopus* spp. [26]. In a study of Ghidini et al. [6], Aflatoxin M1 levels in organic (Mean 35 ng/L; Range <5–93 ng/L) was found to be higher than conventional (Mean 21 ng/L; Range <5–66 ng/L) milk samples. The Aflatoxin M1 levels in 49% of the organic and in 10% of conventional milk samples were higher than the legal limit of 50 ng/L, which was set by EU Regulation 466/2001. However, in general, the samples were accepted as safe. In a study analyzing the organic and conventional milk samples for mycotoxins, OTA was detected in 6 out of 40 (11–58 ng/L) conventional milk samples and 5 out of 47 (15–28 ng/L) organic milk samples. OTA was not found in any of 20 baby food. The levels found in milk were higher than 5 ng/kg/day, which is the value for tolerable daily intake-TDI. It has been reported that consumption of such milk would be harmful for children [27]. In Greece, aflatoxin M1 (AFM1) (range 5–10 ng/L) was detected by ELISA in 196 different types (conventional, organic and children's milk) of milk samples collected from the market between November 2009 and June 2010. However, the AFM1 level determined in only two of the samples were higher than the maximal limit set by EU [28]. In a study conducted in Italy, feed and serum of conventional and organic layers and broilers were analyzed, and ochratoxin A (OTA) was found in all of the feed samples (100%). But not above limits set by the EU. OTA rates were high especially in the sera of laying hens on both organic (73%) and conventional (52%) systems, but there was no statistical difference

contamination (*Listeria monocytogenes, E. coli* O157s) [24, 25].

132 Livestock Science

products concerning mycotoxin contamination is limited [25].

between the laying hens vs broiler group [29].

**2.2. Fungal contaminants and mycotoxins in organic animal products**

Although, mineral supplementation in organic animal husbandry is not a routine practice, mineral supplements can be applicable. The diet of the animals in organic farming must be 100% organic [31]. Since organic animals depend on the mineral content in the soil, unlike the expectation, mineral deficiencies can occur in animals. This condition usually results in lower essential elements levels in organic animal products compare to conventional animal products. A study conducted in Spain investigating the levels of essential elements such as Cobalt (Co), Chromium (Cr), Copper (Cu), Ferrous (Fe2+), Iodine (I), Manganese (Mn), Molybdenum (Mo), Nickel (Ni), Selenium (Se) and Zinc (Zn) and toxic elements such as Arsenic (As), Cadmium (Cd), Mercury (Hg) and Lead (Pb) in organic and conventional milk samples has revealed that levels of essential elements in organic milk is lower than conventional milk and toxic element concentrations are lower in both without any significant difference [32]. The analysis of pork obtained from slaughterhouses (n: 20) has shown that As, Pb and Hg (excluding one sample, 0.008 mg/kg) are below the detection limit (0.1, 0.05 and 0.005 mg/kg, respectively). In the same samples, Cd levels were between 0.005 and 0.38 mg/kg (median: 0.11 mg/kg), which were lower than the limits set by the EU (1 mg/kg) [13].

Heavy metals are persistent pollutants like organic chlorine and polychlorinated biphenyl (PCB) pesticides. Since heavy metals still exist in production processes for different purposes, they can be found in high levels in various environmental samples especially in pastures close to industrial areas [6]. Heavy metals enter the body through inhalation of their dust, drinking of the contaminated water or ingestion of the products grown in the contaminated regions (food chain) [33].

Some researchers have shown that levels of harmful elements such as Pb, As, Cd and Ni in organic products are not lower than those found in conventional products [6, 34, 35]. In a study evaluating a total of 156 organic and conventional milk and meat products (78 samples in each group), the mean Pb levels were detected as 1.85 and 1.68 μg/L and the mean Cd levels were detected as 0.09 and 0.16 μg/L in organic and conventional milk samples, respectively. In meat samples, the means of 5.91 and 14.81 μg/L Pb and the means of 0.49 and 1.31 μg/L Cd were detected in organic and conventional samples, respectively. Pb levels in organic and conventional milk samples were not higher than the 20 μg/L, which was set by EU Regulation 466/2001. There is no maximum residue limit (MRL) value for Cd-concerning milk. In the case of meat samples, Pb and Cd levels were lower than 100 and 50 μg/kg, which were set by EU Regulation 466/2001, respectively [6].

In Poland, milk and hair samples obtained from Holstein cow on organic farms were analyzed for Aluminum (Al), As, Barium (Ba), Cd, Cr, Cu, Fe, Hg and Pb, and the mean values of these elements in milk samples were 63.64, 12.27, 26.36, 1.130, 15.76, 157.6, 785.7, 0.396 and 6.210 μg/kg, and the mean values in hairs were 14224, 34.82, 298.7, 2.700, 75.76, 2263, 15925, 82.78 and 32.67 μg/kg, respectively [36].

In Turkey, in a study conducted on milk and milk products offered to consumption between March 2010 and February 2011, samples of conventional and organic products were collected at three monthly intervals and analyzed by Graphite Furnace AAS for Al, As, Cd and phosphorus (P), and the levels of these elements were found lower than limit of detection-LOD values, which were 0.02, 0.001, 0.001 and 0.02 μg/L for Al, As, Cd and Pb, respectively. Mean Pb levels were found as 0.001 ppm in organic milk (n:3) while 0.008 ppm in organic cheeses (n:7). There is not a maximal limit set by Turkish authorities for organic products, therefore, when 0.02 ppm, which was set as maximal acceptable value for the milk according to Turkish Food Codex "Communiqué on Determination of Maximum Level of Certain Contaminants" (Communiqué No: 2002/63) in foodstuffs, was taken as the basis, the Pb levels determined in one organic cheese and in one organic butter were above the maximum acceptable level [37, 38].

In a study performed in Turkey (Aegean Region) for determining the mineral content of the organic and conventional chicken eggs, compare to conventional chicken eggs, P and Zn levels in the edible portion of organic chicken eggs were lower, whereas Mg was higher in shell, and there was no difference between organic and conventional eggs concerning calcium (Ca), Fe and Cu contents [39]. In Turkey, 0.020, 0.055 and 0.020 mg/L of Cd, Pb and Cu, respectively, were found below the LOD in all of the organically and conventionally produced flower honey and eggs by analysis, whereas Fe concentrations were found at higher levels in organic compared to conventional products [40].

In Greece, in a controlled study, Cu, Vanadium (V), Cr, Ni, As and Cd contents were determined in conventional, organic and free-range (in the courtyard) chicken eggs, and mean values for these elements were determined as 1357, 12.5, 66.2, 63.3, 13.9, 1.4 ng/g in conventional, as 1233, 13.2, 82.9, 58.4, 12.5, 1.6 ng/g in organic and as 1282, 12.6, 90.5, 59.2, 15.4 and 1.5 ng/g in free-range chicken eggs, respectively. The values were lower in white than those in brown eggs [41]. In Egypt, in the analysis of organic eggs for Cd, Pb and Al showed that Cd and Pb were present in 34 and 40% of the organic eggs, respectively. The Cd and Pb contents of the eggs were above the maximum permissible levels. It was emphasized that although, when calculated according to target hazard quotients (THQ) organic eggs appear to have a low health risk, they are not safer than conventional ones [42].

Analysis of Cd levels in liver, kidney and fecal samples as well as feed, soil and water samples collected from a pig farm in which organic (outdoor) and conventional (indoor) breeding systems implemented together showed that Cd levels in organically and conventionally produced feedstuffs were 39.9 and 51.8 μg/kg, respectively. Cadmium content in 38% of the feed given to conventionally reared animals was found to be associated with the Cd content of beet fibers, which was included in to diet at a rate of 5%. No difference was determined between liver samples collected from the animals on organic and conventional feeding systems concerning Cd levels (15.4 ± 3.0 μg/kg). Despite the low amount of Cd in feed, more Cd was found in kidney of pigs fed with organic feed. In addition, Cd levels were higher in the feces of organic pigs, which were attributed to environmental exposures such as soil [43].

#### **2.4. Pesticide residues in organic animal products**

Organic products contain more phytochemicals, which are protective against pests, therefore, use of pesticides is not required, thus the risk of pesticide residues in organic products is low [34]. However, from time to time, pesticides such as DDT and its degradation products, DDE may be found in foods such as organic-grown grain, grain products (biscuits, bread, etc.), meat and dairy products. Despite the use of pesticides in organic farming is not allowed, the reason for the existence of these substances in organic farming is attributed to the ability of them to remain in environment for a long time without disintegration [44]. Pesticides can be encountered in most of the animal products (meat, milk and fish) depending on bioaccumulation. Dioxin and dioxin-like compounds (polychlorinated dibenzo-p-dioxins-PCDD, polychlorinated dibenzofurans-PCDF, and polychlorinated biphenyls-PCBs), which are a general problem of the places in where industrialization is intense or intensely populated create similar problems for organic or conventional farming [45]. It has been stated that 4% of dioxin received by people per day comes from the eggs [46]. It has also been claimed that more dioxin was determined in eggs obtained from free-range hens compared to those obtained from hens grown indoors [45]. In a study conducted on honey for the evaluation of pesticides, it has been emphasized that there is no significant difference between organically and conventionally produced honeys [47]. In northern Italy, in the analysis of conventional and organic animal meat and milk samples for organochlorine pesticides and PCBs, pesticides and PCBs have been found below legal limits in both organic and conventional samples [6]. In another study conducted in Italy, the residues of persistent pollutants and pesticides were determined by GC-MS/MS analysis in most of the 59 organic honey samples. However, levels were below the MRL. This result was attributed to geographical conditions [48]. According to the findings of the United States Department of Agriculture (USDA) pesticide data program (PDP), the market place surveillance program of the California Dept. of Pesticide Regulation (CDPR) and a Consumers Union private residue-testing program, conventional/organic pesticide residue ratios have been found as 3.2, 4.8 and 2.9, respectively. These results seem to relieve the 70% of people who prefer the consumption of organic products to avoid from pesticides [49].

#### **2.5. Veterinary drug residues in organic animal products**

In Turkey, in a study conducted on milk and milk products offered to consumption between March 2010 and February 2011, samples of conventional and organic products were collected at three monthly intervals and analyzed by Graphite Furnace AAS for Al, As, Cd and phosphorus (P), and the levels of these elements were found lower than limit of detection-LOD values, which were 0.02, 0.001, 0.001 and 0.02 μg/L for Al, As, Cd and Pb, respectively. Mean Pb levels were found as 0.001 ppm in organic milk (n:3) while 0.008 ppm in organic cheeses (n:7). There is not a maximal limit set by Turkish authorities for organic products, therefore, when 0.02 ppm, which was set as maximal acceptable value for the milk according to Turkish Food Codex "Communiqué on Determination of Maximum Level of Certain Contaminants" (Communiqué No: 2002/63) in foodstuffs, was taken as the basis, the Pb levels determined in one organic

cheese and in one organic butter were above the maximum acceptable level [37, 38].

compared to conventional products [40].

134 Livestock Science

health risk, they are not safer than conventional ones [42].

**2.4. Pesticide residues in organic animal products**

In a study performed in Turkey (Aegean Region) for determining the mineral content of the organic and conventional chicken eggs, compare to conventional chicken eggs, P and Zn levels in the edible portion of organic chicken eggs were lower, whereas Mg was higher in shell, and there was no difference between organic and conventional eggs concerning calcium (Ca), Fe and Cu contents [39]. In Turkey, 0.020, 0.055 and 0.020 mg/L of Cd, Pb and Cu, respectively, were found below the LOD in all of the organically and conventionally produced flower honey and eggs by analysis, whereas Fe concentrations were found at higher levels in organic

In Greece, in a controlled study, Cu, Vanadium (V), Cr, Ni, As and Cd contents were determined in conventional, organic and free-range (in the courtyard) chicken eggs, and mean values for these elements were determined as 1357, 12.5, 66.2, 63.3, 13.9, 1.4 ng/g in conventional, as 1233, 13.2, 82.9, 58.4, 12.5, 1.6 ng/g in organic and as 1282, 12.6, 90.5, 59.2, 15.4 and 1.5 ng/g in free-range chicken eggs, respectively. The values were lower in white than those in brown eggs [41]. In Egypt, in the analysis of organic eggs for Cd, Pb and Al showed that Cd and Pb were present in 34 and 40% of the organic eggs, respectively. The Cd and Pb contents of the eggs were above the maximum permissible levels. It was emphasized that although, when calculated according to target hazard quotients (THQ) organic eggs appear to have a low

Analysis of Cd levels in liver, kidney and fecal samples as well as feed, soil and water samples collected from a pig farm in which organic (outdoor) and conventional (indoor) breeding systems implemented together showed that Cd levels in organically and conventionally produced feedstuffs were 39.9 and 51.8 μg/kg, respectively. Cadmium content in 38% of the feed given to conventionally reared animals was found to be associated with the Cd content of beet fibers, which was included in to diet at a rate of 5%. No difference was determined between liver samples collected from the animals on organic and conventional feeding systems concerning Cd levels (15.4 ± 3.0 μg/kg). Despite the low amount of Cd in feed, more Cd was found in kidney of pigs fed with organic feed. In addition, Cd levels were higher in the feces

of organic pigs, which were attributed to environmental exposures such as soil [43].

Organic products contain more phytochemicals, which are protective against pests, therefore, use of pesticides is not required, thus the risk of pesticide residues in organic products is low Outdoor rearing of animals in organic livestock production system may increase the risk of animals to contact with environmental pathogens that cause foot diseases (especially in pigs) as well as infectious diseases and helminthiasis. Lack of use of the curative and preventive conventional medicines (antibiotics) in organic farming leads to concerns about the treatment of the diseases. Mastitis is one of the most common diseases seen in dairy animals. Mastitis incidence is reported to be higher in organic production than in conventional production in England, Germany, to a lesser extent in Norway, Sweden and Denmark. However, it has been indicated that the difference between conventional and organic farming is decreased with the increasing awareness of animal production [4]. Since the use of veterinary drugs has not been allowed in organic livestock production, screening organic animal products for veterinary drug residues is at negligible levels. However, in a study conducted by Ghidini et al. [6], the antibiotic residues have been found at low levels, approximately 0.3%, in milk. In a study conducted before 1997, no difference was reported between conventional and organic honey in terms of veterinary drug residues [47]. In the analysis of kidney and meat samples of organic pigs (n = 20) taken from slaughterhouses, solely one sample showed a slight bacterial inhibitory effect against macrolide antibiotics. All of the organic and conventional eggs were found negative by the analyses for toltrazuril aminoglycosides, sulfonamides, beta-lactam antibiotics, tetracyclines, quinolones and colistin residues [13].
