Nadia Waegeneers

Assessment of the chemical contamination in home-produced eggs in Belgium: general overview of the CONTEGG study.

This overview paper describes a study conducted for the Belgian Federal Public Service of Health, Food Chain Safety and Environment during 2006-2007. Home-produced eggs from Belgian private owners of hens were included in a large study aiming to determine concentration levels of various environmental contaminants. By means of the analyses of soil samples and of kitchen waste samples, obtained from the same locations, an investigation towards the possible sources of contaminants was possible. Eggs, soils, faeces and kitchen waste samples were checked for the presence of dioxins, PCBs (including dioxin-like PCBs), organochlorine pesticides, trace elements, PAHs, brominated flame retardants and mycotoxins. The study design, sampling methodology and primary conclusions of the study are given. It was found that in some cases dioxin-like compounds were present at levels that are of concern for the health of the egg consumers. Therefore, measures to limit their contamination in eggs, produced by hens of private owners, were proposed and deserve further attention.

PCDD/Fs and dioxin-like PCBs in home-produced eggs from Belgium: levels, contamination sources and health risks

This paper discusses the dioxin TEQ levels as determined by the chemically activated luciferase gene expression assay (CALUX) and by HRGC-HRMS in eggs, soils, faeces and kitchen waste samples obtained in the CONTEGG study. The samples were collected in each Belgian province at private homes and in small gardens where chickens are held. The CALUX levels for eggs sampled in autumn were higher than the levels in eggs obtained at the same locations in spring (median values of 5.86 and 4.08 pg CALUX TEQ/g fat, respectively). The total WHO-TEQ levels in eggs, determined by HRGC-HRMS, ranged from 3.29 to 95.35 pg TEQ/g fat in autumn and from 1.50 to 64.79 pg TEQ/g fat in spring. In the soils on which the chickens forage, levels of 2.51-11.35 pg I-TEQ/g in autumn and 2.00-7.86 pg I-TEQ/g in spring were found. The congener pattern of PCDD/Fs in the eggs, soils and faeces was dominated by OCDD, in addition to 1,2,3,4,6,7,8-HeptaCDD, OCDF and 1,2,3,4,6,7,8-HeptaCDF. The predominant dioxin-like PCBs were PCB118, PCB 105 and PCB 156. The dioxin-like PCBs contributed on average 47%, 14% and 20% to the total WHO-TEQ in eggs, soils and faeces, respectively. Kitchen waste samples were very low-contaminated with dioxin-like compounds. The present results showed a good agreement between egg and soil TEQ levels for PCDD/Fs but not for dioxin-like PCBs. This study showed that current soil levels found in some private gardens do not lead to egg levels below the current EU maximal level of 6 pg total TEQ/g fat for dioxins and dioxin-like PCBs. The consumers of the analysed eggs attained 5-79% of the tolerable weekly intake (TWI) of 14 pg TEQ/kg bw for dioxins and dioxin-like PCBs by exposure to their home-produced eggs only.

Transfer of soil contaminants to home-produced eggs and preventive measures to reduce contamination

Uptake studies have shown that chickens foraging on soils contaminated with environmental pollutants accumulate these compounds into their eggs. Home-produced eggs thereby show higher contamination levels than commercially produced eggs. It was the aim of this study to identify the major source of two environmental pollutants in home-produced eggs, i.e. dioxins and lead, to formulate preventive measures to reduce the contamination levels of such eggs, and to assess the feasibility of the formulated measures in terms of the perception and behavior of private egg producers towards such measures. The major source of dioxins and lead in eggs, i.e. the soil, was identified by transfer calculations of the pollutants from the feed and soil towards eggs. Preventive measures to reduce soil intake or geophagy and hence egg contamination levels, were formulated and their feasibility evaluated through interviews with private chicken owners. The results show that a paved surface inside the henhouse, an indoor feeding place and providing a sufficient surface area per chicken were considered the most appropriate in terms of feasibility and willingness to apply the measures by the private chicken owners. To enhance the effect of the measures, a combination of measures supported and promoted at policy level is considered as a good strategy to reduce contamination levels in home-produced eggs.

Selenium content of Belgian cultivated soils and its uptake by field crops and vegetables

A series of 695 food crops were collected on 539 soils throughout Belgium. All samples were collected on commercial production fields, omitting private gardens. All crops were analyzed for their selenium (Se) concentration. The soils represent different soil types occurring in Belgium, with soil textures ranging from sand to silt loam, and including a few clay soils. They were analyzed for Se concentration, organic carbon content, cation exchange capacity and extractable sulphur (S) concentration. The Se concentrations in the soils were low (range 0.14-0.70 mg kg(-1) dw), but increasing soil Se concentrations were observed with increasing clay content. Stepwise multiple regressions were applied to determine relations between Se concentrations in crops and soil characteristics. Among field crops, wheat is the most important accumulator of selenium but the concentration remains rather low on the Belgian low Se-soils. Based on dry weight, leafy vegetables contain more Se than wheat. The soil is the most important source of Se and the element is transported with the water stream to the leaves, where it is accumulated. Vegetables rich in S, e.g. some Brassica and Allium species, have a higher capacity to accumulate Se as it can replace S in the proteins, although this accumulation is still limited at low soil Se concentrations. In loamy soils, weak correlations were found between the soil Se concentration and its concentration in wheat and potato. The uptake of Se increased with increasing pH. The Se concentrations in Belgian soils are far too low to generate a driving force on Se uptake. General climatic conditions such as temperature, air humidity and soil moisture are also important for the transfer of Se within the plant, and plant linked factors such as cultivar, growth stage and edible part are important as well, although their influence remains limited at low soil Se concentrations.

PCB and organochlorine pesticides in home-produced eggs in Belgium

The level of polychlorinated biphenyls (PCB) and persistent organochlorinated pesticides (OC) in home-produced eggs was investigated in Belgium. The concentration of dichlorodiphenytrichloroethane (DDT) is above the norm for 17% of the eggs collected during the spring on 58 different locations. For PCB, aldrin, dieldrin, and chlordane, 3-5% of the samples are above the norm too. These levels are surprisingly high for compounds banned for about 30 years. Higher concentrations in home-produced eggs are expected compared to battery eggs because of contact with the environment and especially the soil. For ten selected locations, the concentration in soils, excreta and feed was measured, but no simple correlation between egg and feed or soil level could be established. Hexachlorohexane, endosulfan, endrin, methoxychlor and nitrofen were not detected in any sample.

Effect of leaching and aging on the bioavailability of lead to the springtail Folsomia candida

Because it is unclear if leaching can account for differences in metal bioavailability observed between metal-spiked soils and historically contaminated field soils, we simultaneously assessed Pb toxicity to the springtail Folsomia candida in three transects of Pb-contaminated soils and in leached and unleached soils spiked at similar total Pb concentrations. Total Pb concentrations of 3,877 mg/kg dry weight and higher always caused significant effects on F. candida reproduction in the spiked soils. In the transects, only the soil with the highest Pb concentration of 14,436 mg/kg dry weight significantly affected reproduction. When expressed as pore-water concentrations, reproduction was never significantly affected at Pb concentrations of 0.539 mg/L, whereas reproduction was always significantly affected at Pb concentrations of 0.678 mg/L and higher, independent of the soil treatment. These results indicate that pore-water Pb concentrations can explain, at least in part, the observed differences in the toxicity data expressed as total Pb concentrations. Leaching after the spiking procedure only caused small differences in Pb toxicity and, therefore, cannot account for toxicity differences between laboratory-spiked soils and historically contaminated field soils.

Genotypic effects in phytoavailability of radiocaesium are pronounced at low K intensities in soil

The differences in radiocaesium uptake between species were analysed in a series of solution culture and pot trials. Since radiocaesium uptake is very sensitive to the solution potassium (K) concentration, it was hypothesised that species depleting K in the rhizosphere to a larger extent, will have a higher radiocaesium uptake. Five species (bean, lettuce, winter barley, ryegrass and bentgrass) were grown for 18–21 days in nutrient solution spiked with 137Cs and at 4 K concentrations between 0.025 and 1.0 mM. Shoot 137Cs activities all decreased between 17- and 81-fold with increasing K supply. Shoot 137Cs activities were 4-fold different between species at the lowest K supply and 3.4-fold different at high K supply. The same five species were grown in two 134Cs spiked soils with contrasting exchangeable K but similar clay content. Shoot 134Cs activities were up to 19-fold higher in the soil with lowest exchangeable K. Differences in shoot activity concentrations between the species were only 4.5-fold in the high K soil, but were 15-fold in the low K soil. Bulk soil solution 134Cs and K concentration data were combined with radiocaesium uptake characteristics measured in solution culture to predict radiocaesium uptake from soil. Predictions were within 1.6-fold of observations in the high K soil but largely underestimated 134Cs uptake in lettuce, ryegrass and barley in the low K soil. A solute transport model was used to estimate K and radiocaesium concentrations in the rhizosphere. These calculations confirmed the assumption that higher radiocaesium uptake is found for species that deplete K in the rhizosphere to a larger extent.

Impact of atmospheric deposition of As, Cd and Pb on their concentration in carrot and celeriac.

Root crops, carrot and celeriac, were exposed to atmospheric deposition in a polluted versus reference area. An effect was observed on the As, Cd and Pb concentrations of the leaves and the storage organs. The concentrations in the whole storage organs correlated well with atmospheric deposition, which shows that they even could be used for biomonitoring. Nevertheless, leaves remain much more appropriate. The results revealed also a significant increase of the As and Cd concentration in the consumable part of the storage organs as a function of their atmospheric deposition. As such the experiments allowed deriving regression equations, useful for modeling the atmospheric impact of trace elements on the edible parts of root crops. For Pb, however, there was hardly any significant impact on the inner parts of the storage organs and as such the transfer of Pb in the food chain through root crops can be considered to be negligible.

Mycotoxin analyses in some home produced eggs in Belgium reveal small contribution to the total daily intake

Low levels of deoxynivalenol (DON, range: 2.6-17.9 ng/g) and its metabolite de-epoxy-DON (DOM-1, range: 2.4-23.7 ng/g) were found in 20 home-produced egg samples collected in Belgium during autumn 2006 (from 10 breeders) and spring 2007 (same breeders). DON intake assessment showed that the consumption of these eggs may contribute to less than 1% of the provisional maximum tolerable daily intake of 1 microg/kg body weight established by FAO/WHO. None of the egg samples analyzed had quantifiable levels of zearalenone (ZEA), alpha-zearalenol, beta-zearalenol, ochratoxin A (OTA) and citrinin (CIT). Intake of DON, ZEA, OTA and CIT via the consumption of home produced eggs seems not to be a matter of concern. Despite this, we recommend to continue in screening other eggs allowing to increase the sample size and the subsequent conclusion for mycotoxin contamination in eggs. As home produced food is generally not submitted to any compliance control and may be consumed in large quantities by their producers and other household members, it is worthwhile to further pay attention to the quality of feed as well as the environment in which the hens live.

Accumulation of trace elements in cattle from rural and industrial areas in Belgium.

Trace element concentrations were determined in meat, kidney and liver tissue of cattle, which had resided more than 18 months in areas historically contaminated by emissions from the non-ferrous metal industry or in regions with normal background metal contamination levels in Belgium. Trace element levels were determined by inductively coupled plasma–mass spectrometry. Lead, arsenic and cadmium concentrations in meat were low for all cattle. Concentrations in kidneys were, respectively, 1.8-, 2.2- and 2.5-fold higher in cattle from the contaminated areas compared to animals from reference areas. The European maximum level for cadmium in kidney was exceeded by 75% of the kidneys from contaminated areas and 47% of the kidneys from reference areas. Lead, arsenic and cadmium concentrations in bovine livers from contaminated areas were increased by a factor of 2.3. Zinc levels in livers and kidneys were within normal ranges, but 20% higher in the contaminated areas compared to reference areas. Copper levels in livers were high in all areas. Dairy cattle accumulated significantly higher levels of cadmium in kidneys and of lead in liver and kidneys than did beef cattle.