Food contamination is a serious problem because high levels of chemical compounds in food products pose a serious threat to consumer health. Chemical contaminants include environmental contaminants (e.g. heavy metals, dioxins), process contaminants that are formed when food is cooked or heated (e.g. acrylamide, polycyclic aromatic hydrocarbons) and chemical contaminants used for economically justified adulteration (e.g. melamine). Some contaminants may originate from several sources.
The general principles and requirements of European food law are contained in Regulation (EC) No. 178/2002 of the European Parliament and of the Council of 28 January 2002 laying down the general principles and requirements of food law, establishing the European Food Safety Authority and laying down procedures in matters of food safety, as amended. In this act, the European Union declares that “the safety and confidence of consumers within the Community and in third countries is of paramount importance”. Article 14 of the aforementioned regulation establishes that ‘no unsafe food shall be placed on the market’.
Maximum levels for certain harmful substances in food are laid down in Commission Regulation (EC) No 1881/2006 of 19 December 2006 setting maximum levels for certain contaminants in foodstuffs, as amended. The following groups of contaminants are listed in the annex to this regulation:
- nitrates,
- mycotoxins,
- metals,
- 3-monochloropropane-1,2-diol (3-MCPD), 3-MCPD fatty acid esters and glycidyl esters of fatty acids,
- dioxins and dioxin-like polychlorinated biphenyls (PCBs) and the six indicator PCBs,
- Polycyclic aromatic hydrocarbons (PAHs),
- melamine and its structural analogues,
- plant-specific toxins,
- perchlorate.
NITRATES
Nitrates (nitrate V) are used in agricultural production as fertilisers and in the food industry as preservatives. Commission Regulation (EC) No 1881/2006 of 19 December 2006 setting maximum levels for certain contaminants in foodstuffs, as amended, sets maximum levels for nitrates in fresh and processed spinach, in lettuce, as well as in processed cereal-based foods and baby foods for infants and young children. Regarding the legal requirements for the use of nitrates as preservatives, Regulation (EC) No 1333/2008 of the European Parliament and of the Council of 16 December 2008 on food additives, as amended, applies.The nitrate content depends on the plant species, its parts and also on environmental conditions. The highest nitrate content is found in root vegetables and tubers and in vegetables intended for early harvest. Based on their tendency to store nitrate, vegetables can be divided into those containing:
- small quantities, e.g. tomato, cucumber, green beans, peas, peppers
- medium quantities, e.g. celery, carrots, parsley root
- large quantities, e.g. spinach, lettuce, early cabbage, radishes, beetroot, potatoes
Nitrite (nitrate III) is present in fresh vegetables in small quantities, but during storage can increase due to microbiological nitrate reduction (Bacillus, Aerobacter, Escherichia). Nitrates (V) and nitrates (III) are also found in raw materials of animal origin, where they enter with feed and drinking water.
In the laboratories of J.S. Hamilton Poland analyses of nitrates and nitrites are performed in accordance with validated and accredited methods based on Polish and international standards and own research procedures, using spectrophotometric techniques and high-performance liquid chromatography with UV or DAD detection. The most frequently analysed products are: fruit and vegetables and processed fruit and vegetables, potatoes, milk powder, meat and meat products, cheese.
MONOCHLOROPROPANE-1,2-DIOL (3-MCPD), 3-MCPD FATTY ACID ESTERS AND GLYCIDYL ESTERS OF FATTY ACIDS
Commission Regulation (EC) No 1881/2006 of 19 December 2006 setting maximum levels for certain contaminants in foodstuffs as amended sets separate maximum levels for:
- 3-monochloropropane-1,2-diol (free 3-MCPD)
- sum of 3-MCPD and 3-MCPD fatty acid esters, expressed as 3-MCPD
- glycidyl esters of fatty acids expressed as glycidyl
3-MCPD is a group of contaminants known as chloropropanols. Free 3-MCPD was first identified as an impurity in acid hydrolysed vegetable proteins and soy sauce, and was later found in other foods. 3-MCPD and its esters can be formed from glycerol or acylglycerols in fat-containing and heat-treated foods in the presence of chloride ions. Glycidyl fatty acid (GE) esters are processing-induced impurities found mainly in refined fats and oils and foods containing fats and oils. It was initially assumed that 3-MCPD and GE esters are formed by similar processes, but it is now known that their formation mechanisms are different. The highest concentrations are usually found in refined palm oil and oleic palm oil, but 3-MCPD and GE esters are also found in other refined vegetable oils such as safflower, coconut, sunflower and soybean oils and refined marine oils such as fish oils
In the laboratories of J.S. Hamilton Poland the analysis of 3-MCPD, 3-MCPD esters and GE is performed according to a validated and accredited method based on the AOAC standard using the technique of gas chromatography coupled to mass spectrometry.
MELAMINE AND ITS STRUCTURAL ANALOGUES
Melamine is widely used in the manufacture of paints, plastics, cookware and utensils, and fertilisers, among others. However, melamine and its structural analogue cyanuric acid came under the spotlight of food control laboratories in 2008 after cases of adulteration of animal feed, milk powder and infant formula to fraudulently increase the protein content of these products. In 2008, four infant deaths and over 54,000 cases of illness were reported in China, attributed to the consumption of melamine-contaminated milk. The reason for the illegal addition of melamine to these products was the high nitrogen content (66%) of the melamine molecule. Commonly used methods for protein determination, based on analysis of the nitrogen content of a sample, e.g. the Kjeldahl method, do not distinguish between nitrogen from protein and non-protein nitrogen. Therefore, the addition of this substance resulted in a false increase of the protein level in the product.
Melamine and its hydrolysis products (ammelin, ammelide and cyanuric acid) may also contaminate food due to the pesticides used, as they are metabolites of certain insecticides e.g. cyromazine, fungicides e.g. anilazine and herbicides e.g. terbutylazine, promethrin, simazine, atrazine, amethrin and cyanazine. Cyromazine first leads to melamine, which is then gradually hydrolysed to cyanuric acid. Of the above compounds, only terbutylazine and cyromazine are currently still used in the EU. Another source of contamination of food with melamine and its analogues is the use of cyanamide-based fertilisers. Cyanamide is known to form melamine through trimerisation. Another source of cyanuric acid is di- and trichloroisocyanurates, which are contained in cleaning agents, algicides and disinfectants.
Commission Regulation (EC) No 1881/2006 of 19 December 2006 setting maximum levels for certain contaminants in foodstuffs as amended sets maximum levels for melamine and its analogues in food for two categories: food excluding infant formulas and follow-on formulas (maximum level of melamine 2.5 mg/kg) and infant formulas and follow-on formulas powder (maximum level of 1 mg/kg).
The J.S. Hamilton Poland laboratory was the first commercial laboratory in Poland to validate and accredit a method for the determination of melamine in food, based on gas chromatography with mass spectrometry detection, back in 2009. Currently we offer the possibility of determination of these compounds using liquid chromatography with tandem mass spectrometry detection.
PLANT-SPECIFIC TOXINS
Plant toxins occur naturally in some plant species and are produced by plants, for example, as a defence mechanism. Sometimes plants containing such toxins appear as weeds in food crops, which means that seeds or leaves may accidentally get mixed with the main crop during harvest. For this reason, low levels of these toxins can be detected in cereals, herbal products, teas, salads, grains and animal products. Typical examples are pyrrolizidine alkaloids and tropane alkaloids. Some other toxins are natural components of plant products, such as erucic acid in some oils, hydrocyanic acid in apricot kernels or opium alkaloids in poppies.
ERUCIC ACID
It is mainly found in seeds of the Brassicaceae species, which include seed crops such as rapeseed and mustard, as well as vegetable crops such as the diverse group of kale, cabbage and turnips. Brassica vegetables may contain only trace amounts of erucic acid, while seeds may contain high levels. Brassicaceae varieties with very low levels of erucic acid have been developed for seed oil production for food and feed use in most countries, including the EU. Commission Regulation (EC) No 1881/2006 of 19 December 2006 setting maximum levels for certain contaminants in foodstuffs, as amended, established a maximum level for erucic acid in vegetable oils and fats and mustard.
The criteria for erucic acid in infant formulas and follow-on formulas ready for use are set out in Commission Delegated Regulation (EU) 2016/127 of 25 September 2015 supplementing Regulation (EU) No 609/2013 of the European Parliament and of the Council as regards the detailed compositional requirements and information on infant formulas and follow-on formulas and as regards information on the nutrition of infants and young children, as amended.
TROPANE ALKALOIDS
They are toxic secondary metabolites that occur naturally in plants from several families, including the Brassicaceae, Solanaceae (e.g. mandragora, black loosestrife, wolfberry, gummy sapwood) and Erythroxylaceae (e.g. common dwarf). They are found in all parts of plants, with the highest concentrations in roots and seeds. The content of individual alkaloids varies according to species, season, location and part of the plant. Seeds of plants producing tropane alkaloids, such as Datura stramonium of the genus Datura, can be found as contaminants in agricultural crops such as linseed, soya, millet, sunflower and buckwheat.
A scientific report published by EFSA in 2018 presented an assessment of human exposure to tropane alkaloids based on 44,000 results for nearly 7,400 samples. Most samples did not contain alkaloids (i.e. below detection limit or below quantification limit). High concentrations of atropine and scopolamine were recorded in tea and herbal infusions, cereal bars and spices.
The tropane alkaloids referred to in Commission Regulation (EC) No 1881/2006 of 19 December 2006, as amended, are atropine and scopolamine. The current requirements apply to processed cereal-based foods and foods for young children. From 1 September 2022, maximum levels of tropane alkaloids for certain unprocessed cereals and those intended for the final consumer, as well as and herbal infusions, will take effect.
PYRROLIZIDINE ALKALOIDS
They are naturally occurring toxins in many plant species. They are produced by plants as a defence mechanism against herbivorous insects. It is a group of several hundred (over 600) alkaloids occurring in some plants, e.g. from the families of borage (e.g. borage, rosemary, field goldenrod), asteraceae (e.g. burdock, camomile, dandelion, thistle, thistle, daisy, coltsfoot), Fabaceae (legumes) e.g. lupine, violet, St. John’s wort. They are also found in tea (Camellia sinensis), aniseed, lemon balm, mint, vervain, lovage, marjoram, caraway, oregano.
Foods may contain pyrrolizidine alkaloids as a result of contamination with plants containing these compounds. Potential sources of exposure include dietary supplements with honey and pollen (if bees collected pollen from such plants), salad plants and cereals (if contaminated with weeds containing these compounds), herbal products, supplements and teas (prepared with or contaminated with plants containing pyrrolizidine alkaloids) and products of animal origin (meat, milk, eggs – if food-producing animals were fed with plants containing pyrrolizidine alkaloids or feed contaminated with them).
In December 2020, Commission Regulation (EU) 2020/2040 of 11 December 2020 amending Regulation (EC) No 1881/2006 as regards maximum levels for pyrrolizidine alkaloids in certain foodstuffs was published.
The maximum levels relate to the sum of 21 pyrrolizidine alkaloids and 14 additional isomers, will apply from July 2022 and will cover teas, herbal teas, flavoured teas, food supplements, dried herbs, cumin.
OPIUM ALKALOIDS
This group of alkaloids includes morphine, codeine, thebaine, papaverine, noscapine and oripavine. Some of these, mainly morphine and codeine, are contaminants of poppy seeds and products made from them. Poppy seeds are obtained from the sea poppy. While the poppy plant contains opium alkaloids, the poppy seeds themselves contain no or only very low levels of opium alkaloids but may be contaminated with alkaloids as a result of damage by insects or by contamination of the seeds during harvesting when particles of straw dust attach to the seeds or when the seeds come into contact with the milky sap of the stems, leaves or immature poppies. Another cause may be the use of inappropriate (high-morphine) poppy varieties. Treatment processes of the raw material (washing, grinding, heating) cause a decrease in the level of contamination.
In December 2021, Commission Regulation (EU) 2021/2142 of 11 December 2020 amending Regulation (EC) No 1881/2006 as regards maximum levels for opium alkaloids in certain foodstuffs was published. The maximum level will take effect from July 2022 and refers to the sum of morphine and codeine, with codeine content multiplied by a factor of 0.2 (morphine equivalent) to be added to the morphine content due to the similar toxic effect of codeine to morphine, but nevertheless weaker. Maximum levels have been established for poppy seeds placed on the market for the final consumer and for bakery products containing poppy seeds or products derived thereof. The manufacturer of bakery products should be in possession of specific information on the morphine equivalent content of poppy seeds used as ingredients in bakery products and the supplier of poppy seeds should communicate this information to the manufacturer of bakery products.
HYDROGEN CYANIDE AND CYANOGENIC GLYCOSIDES
Cyanogenic glycosides are phytotoxins (toxic chemicals produced by plants) that are found in at least 2000 plant species, many of which are used as food in some parts of the world. Manioc, sorghum, stone fruits, linseed, bamboo roots and almonds are particularly important foods containing cyanogenic glycosides. Mechanical damage to plant cells, e.g. by grinding or chewing, results in the release of hydrogen cyanide through enzymatic hydrolysis of cyanogenic glycosides. Hydrogen cyanide is easily absorbed from the gastrointestinal tract and rapidly distributed to all organs.
The best known cyanogenic glycoside is amygdalin, which is found in almonds, apricot, plum, peach and cherry seeds. Prulaurasine, sambunigrine and vicianin belong to the same group of compounds. These compounds may also be present in processed foods, such as various types of liqueurs and alcoholic beverages.
Commission Regulation (EC) No 1881/2006, as amended, sets maximum levels for unprocessed whole, ground, crushed, shelled, chopped apricot kernels placed on the market and intended for the final consumer.
The J.S. Hamilton Poland laboratory offers methods for the determination of the above plant toxins naturally occurring in certain plant species.
PERCHLORATE
The perchlorate ion is very stable in water and its salts are well soluble in water. Perchlorate occurs naturally in the environment, in nitrate and potash deposits, and can form in the atmosphere and precipitate into soil and groundwater. It also occurs as an environmental pollutant from the use of nitrogen fertilisers and from the production, use and disposal of ammonium perchlorate used in rocket fuel, explosives, fireworks, flares and airbag inflators and other industrial processes. Perchlorate can also be formed during the breakdown of sodium hypochlorite used for water disinfection and can contaminate water. Water, soil and fertilisers are considered potential sources of perchlorate contamination of food.
From 1 July 2020, the requirements of Commission Regulation (EU) 2020/685 of 20 May 2020 amending Regulation (EC) No 1881/2006, which sets maximum levels for perchlorate in fruit and vegetables, herbs, tea and dried herbal and fruit infusions, infant formulas and follow-on formulas, food for special medical purposes intended for infants and young children, infant formulas, baby foods and processed cereal products, apply.
J.S. Hamilton Poland performs analyses of perchlorates, including chlorates, in food in the specialised laboratory of Hamilton UO-Technologia Sp. z o.o. in Słomczyn (AB 1537).
Contact our team today to learn more – or to schedule tests with J.S. Hamilton.
