Preparation and Submission of Extended Ab-Stracts for the Joint Organic Congress 2006 s1
Total Page：16
File Type：pdf, Size：1020Kb
Contaminants and micro-organisms in organic and conventional food products.
L.P.L. van de Vijver, L.A.P. Hoogenboom, N.J.G. Broex, J. van der Roest, J.G. Bokhorst, M.D. Northolt, D. Mevius, J.A.C. Meijs
Abstract - In the Netherlands we investigated animal Netherlands and give a reasonable good impression and plant products on potentially hazardous contam- of the Dutch food pattern. Further fattening pigs, ination with heavy metals, mycotoxins, pesticide dairy cows, laying hens and eggs, and broilers were residues, pathogenic micro-organisms and nitrate. In investigated. Contaminants investigated were; most cases, the organically produced foods had equal heavy metals, mycotoxins, pesticides, nitrate, Sal- or lower amounts of contaminants than convention- monella, E.coli O157, Campylobacter, antibiot- ally produced products. These results conflict with a common idea that organic farming theoretically in- ic-resistant bacteria and veterinary medicines. In creases food safety risks. For many contaminants or- table 1 the investigated food items and the paramet- ganic food showed a large diversity in the amount of ers for contamination are presented. contamination. Experience with organic farming, managing and manure use partly explain these differ- Table 1. food products and parameters ences. Understanding of these cultivation parameters Food product Contaminants can help in further improvement of organic cultivation Wheat Heavy metals, mycotoxins, pesticides practices.1 Lettuce Heavy metals, nitrate, pesticides, sal- monella, E coli O157 Carrot Heavy metals, nitrate, pesticides INTRODUCTION Potato Heavy metals, nitrate, pesticides Organic farming is a cultivation system which theor- etically can lead to problems concerning food safety. Fattening pig Salmonella, E coli O157, Campylobac- One of the common ideas in conventional farming is ter, antibiotic resistant bacteria in ma- that organic products will contain more mycotoxins nure, heavy metals and veterinary and that micro-organisms such as Salmonella and E. medicines in meat and kidney coli will be more common on organic plants because Dairy cows E coli O157 in manure, veterinary medi- of the use of organic manure. Further, the outdoor cines in kidney run of animals might enhance the chance of bacteri- Laying hens Salmonella in manure, heavy metals, al contamination and therefore is thought to be antibiotics and coccidiostatica in eggs more common in organic farming. Broiler Salmonella, E coli O157, Campylobacter To further investigate these potentially hazardous and antibiotic resistant bacteria in ma- contaminants a study was undertaken in which the nure organic farming system was investigated and com- pared with data from conventional farming, partly The samples were collected at the farms. During the from this study, and partly from other ongoing mon- visits background information on management and itoring studies. The analytical data were combined cultivation techniques was gathered. This included with information on cultivation system, to investig- information on soil properties, plant variety, sowing- ate the underlying reasons for the observed differ- planting- and harvesting dates, manure use, irriga- ences. tion system and type of water, way of harvesting, history on crops, green manuring and applied ma- METHODS nure (type and amount) over the past 6 years and In this study several plant and animal food products processing and packaging after harvest (for lettuce). were investigated on the presence of contaminants This information could be helpful in interpreting the and pathogenic micro-organisms. Wheat, lettuce, analytical results. Further this information might in- potato and carrot were selected because these foods crease the potential of relating an analytical out- are the most successful organic products in the come to one of the cultivation parameters which may lead to an advice to the farmers. 1L.P.L. van de Vijver, J. Bokhorst and M. Northolt ; Louis Bolk Instituut, Driebergen, the Netherlands ([email protected]; In this study organic wheat samples are collected [email protected]). M. Northolt made a major contribution to at 20 farms, lettuce at 24, carrot at 35 and potato at this study. He retired in January. 21 farms. If possible, more foods were sampled at L.A.P. Hogenboom, N.J.G. Broex, J. van der Roest; RIKILT, insti- tute on food safety, Wageningen University, Wageningen the Nether- the same farm. For the animal production, 31 pig- lands. ([email protected]) farms (of the 58 Dutch organic farms), 10 farms D.Mevius, Central Institute for Animal Disease Control, Lelystad, the Netherlands with dairy cows, 10 farms with laying hens (out of J. Meijs, Biologica, Utrecht, the Netherlands the circa 100 Dutch organic farms) and all Dutch or- ganically compared to conventionally produced ganic broiler farms (n=9) were visited and samples poultry and pigs, except in Campylobacters from were collected. poultry where the resistance levels were similar in All samples were taken in the years 2003 and both production systems 2004. DISCUSSION In this study, in which both plant and animal RESULTS products were analysed on their content of potential Vegetables hazardous contaminants and micro-organisms, over- In most conventional and organic wheat samples the all the organic produce scored better or equally good concentrations of the 7 mycotoxins were low and be- as conventionally produced products. Only in carrots neath detection limit. Only after a rainy period (end we observed a higher mean nitrate content in organ- of august 2004) higher levels of DON and zearalen- ic compared to conventional produce and in organic one were found in both cultivation systems. broilers Campylobacter was more abundant. The Levels of the heavy metals cadmium, lead, arsen- range of nitrate in carrots was large (11-864 ic and mercury were below the legal limits. No differ- mg/kg). From the collected information on the farm ences were found between the two cultivation sys- management it is indicated that manure practise, tems. crops in previous years and green manuring are The major part of the conventionally produced parameters which influence the nitrate content. This cabbage lettuce had nitrate levels above the legal information can be used for further improvement of limits, whereas this was true for only one out of 19 organic cultivation. outdoor and 1 out of 10 greenhouse organically pro- In pigs we also saw a difference in Salmonella con- duced cabbage lettuce. For iceberg lettuce no differ- tamination between those farmers with a long ex- ences were found. In carrot the nitrate content perience in organic production and the farmers who ranged from 11-864 mg/kg for organic and from 70 just started with organic production. This informa- to 180 mg/kg for conventionally cultivated carrots. tion is very valuable to explain underlying reasons The organic carrots contained 3 times as much ni- for the differences, but also to support a further im- trate as the conventional carrots. provement of the organic production. The high No residues were found on organically and con- levels of resistant campylobacters in organic poultry ventionally produced wheat, carrot and potato. Only may be explained by introduction of these campy- in 2 samples conventionally produced cabbage lobacters from the environment. lettuce residues were found but levels were beneath the legally allowed levels. CONCLUSIONS Despite the use of dung, none of the samples or- In conclusion, though because of the organic cultiva- ganic lettuce contained Salmonella or E.coli. tion system, risks concerning food safety aspects might be expected, this study showed that overall Animal products organic produce scored better or equally good as The contamination with Salmonella in fattening conventional produce. Further improvements can be pigs appeared to be dependent on the experience made by learning from the experience of other farm- within organic farming. On the farms with little ex- ers. perience ( 1-4 y) around 50% of the manure was contaminated with Salmonella, whereas this was ACKNOWLEDGEMENT true for only 1 out of 14 experienced farms (6-14 y). The study was financed by the Dutch ministery of In conventional farming systems the contamination Agriculture, Nature and Food Quality and the Dutch is around 30%. Campylobacter contamination was Food Safety Authority. comparable between organic and conventionally pro- duced pigs (around 55%) In none of the organic poultry farms (laying hens and broilers) Salmonella was found. In conventional farming Salmonella is known to be present around 10% of the farms (in 2002 respectively 13 and 11%). On all organic broiler farms campylobacter was detected, whereas this was only 40% at the conventional farms. Conform expectations, in kidney and meat of fat- tening pigs and kidney of dairy cows from the organ- ic system no antibiotics were detected. Also no residues of antibiotics or coccidiostatics were found in organically produced eggs. In organic practices the use of anti- biotics is restricted. This was confirmed with the lower numbers of antibiotic-resistant bacteria in or-