Polycyclic aromatic hydrocarbons in milk powders marketed in Argentina and Brazil

The aim of this study was to quantify polycyclic aromatic hydrocarbon (PAH) levels in milk powder samples commercialised in Argentina and Brazil during 2012. Thirty-one samples were available from the retail market. An HPLC method for the determination of PAHs was applied involving a clean-up step with silica cartridges. Recoveries were greater than 79% for all PAHs analysed. Reproducible determination with adequate detection and quantification limits (LOD and LOQ) were attained by HPLC with fluorescence detection for 14 PAHs. Acenaphthylene was determined with a UV–VIS detector. There is no significant difference in any PAHs or in the sum of them between the Argentinean and Brazilian samples. Therefore, the samples were evaluated together. The highest concentration of benzo(a)pyrene (BaP) detected was 0.57 µg kg^?1 in milk powder. Contamination of samples expressed as the sum of 15 analysed PAHs varied between 11.8 and 78.4 µg kg^?1 and as PAH4 (BaP, chrysene, benzo(a)anthracene and benzo(b)fluoranthene) was between 0.02 and 10.16 µg kg^?1. The correlation coefficient for PAH2 (BaP and chrysene) and PAH4 groups was 0.95, for PAH2 and PAH8 it was 0.71, and for PAH4 and PAH8 it was 0.83. All the samples were below the regulatory limit for BaP, but 65% of commercial milk powders do not comply with the European Union limit for PAH4. This is the first report of PAH contamination in powder milk from Argentina and Brazil.     

Polycyclic aromatic hydrocarbons (PAH) in chocolate on the German market

Benzo[a]anthracene (BaA), chrysene (CHR), cyclopenta[c,d]pyrene (CPP), 5-methylchrysene (5MC), benzo[b]fluoranthene (BbF), benzo[k]fluoranthene (BkF), benzo[j]fluGoranthene (BjF), benzo[a]pyrene (BaP), dibenzo[a,h]anthracene (DhA), indeno[1,2,3-cd]pyrene (IcP), benzo[g,h,i]perylene (BgP), dibenzo[a,l]pyrene (DlP), dibenzo[a,e]pyrene (DeP), dibenzo[a,i]pyrene (DiP) and dibenzo[a,h]pyrene (DhP), the 15 SCFPAH, assessed to be relevant as well as benzo[c]fluorene (BcL) recommended by the European Food Safety Authority (EFSA), were analysed in different types of chocolate. The sample preparation included accelerated solvent extraction (ASE), size exclusion chromatography (SEC) and solid phase chromatography using small silica gel columns. The individual PAH were separated by gas chromatography using a VF-17ms GC column and detected by high resolution mass spectrometry (HRMS). The investigation of 40 samples of various types of chocolate with different cocoa contents resulted in a median benzo[a]pyrene (BaP) content of 0.22 μg/kg. Furthermore, the results showed a linear correlation between the content of BaP and the sum content of the 16 priority PAH. Therefore, the analysis of BaP as a leading substance seems to be suitable to estimate the PAH contamination in chocolate.     

Indoor levels of polycyclic aromatic hydrocarbons in homes with or without wood burning for heating

The aim of this study was to investigate the impact of domestic wood burning on indoor levels of polycyclic aromatic hydrocarbons (PAHs). Indoor and outdoor concentrations of 27 PAHs were measured during wintertime in homes with (n= 13) or without (n 0) wood-burning appliances and at an ambient site in a Swedish residential area where wood burning for space heating is common. Twenty-four hour indoor levels of anthracene, benzo(ghi)fluoranthene, cyclopenta(cd)pyrene, benz(a)anthracene, chrysene/triphenylene, benzo(a)pyrene (BaP), indeno(1,2,3-cd)pyrene, benzo(ghi)perylene, and coronene were significantly (about 3- to 5-fold) higher in homes with, compared with homes without, wood-burning appliances. The outdoor levels of PAHs were generally higher than the indoor levelsfor all PAHs exceptforthe methylated phenanthrenes. The total PAH cancer potency (sum of BaP equivalents) was significantly higher (about 4 times) in the wood-burning homes compared with the reference homes, with BaP being the largest contributor, while phenanthrene made the largest contribution to the total PAH concentration in indoor and outdoor air. The median indoor BaP level in the wood-burning homes (0.52 ng/m3) was 5 times higher than the Swedish health-based guideline of 0.1 ng/m3, which was also exceeded outdoors on all days (median 0.37 ng/m3).     

Kinetics of sunflower oil contamination with polycyclic aromatic hydrocarbons from contaminated recycled low density polyethylene film

The possibility of food contamination with polycyclic aromatic hydrocarbons (PAHs) by rediffusion from polyethylene film made of contaminated recycled polyethylene (PE) was tested. PE was contaminated with PAHs by diffusion from water medium spiked with fluoranthene (FI), pyrene (Py), and benzo(a)pyrene (BaP). The PE was recycled by heating at 150°C for 10 min. The recycling process did not affect the PAH concentration in PE. From the recycled PE, a PE film was made and rediffusion of PAHs from the PE film into a sunflower oil was followed for 600 h at 24°C. Diffusion of PAHs into the oil demonstrated the potential of PAH-contaminated PE as a source of contamination of food. The PAH concentration in vegetable oil was linearly dependent on the square root of the storage time. A kinetic equation for PAH rediffusion from PE film into the oil is proposed.     

Benzo(a)pyrene penetration on a smoked meat product during smoking time

The Codex Alimentarius gives recommendations to prevent carcinogenic polycyclic aromatic hydrocarbons (PAH) (represented by benzo(a)pyrene (BaP)) contamination during processing of meat products, including the control of smoking time. The influence of direct smoking time (0, 1, 3, 5 and 7 days) on the relationship between the BaP and moisture content of a typical Spanish smoked meat product called chorizo and the mechanism of BaP penetration and water release from four different depths in the product was studied. Chorizo was studied from the Principality of Asturias, a location never before tested. An analytical method was developed for this purpose consisting of PAH extraction assisted by sonication followed by solid-phase extraction (SPE) sample clean-up and analytical determination using GC-MS. Results show that an increase in smoking time produced contradictory and independent effects on the moisture and BaP content (µg kg^–1) of chorizos. The moisture content decreased from 49.9% to 31.3%. On the other hand, the BaP content increased from less than 0.24 µg kg^–1 to 0.75 µg kg^–1, finally stabilising after 5 days of smoking. After this time, the natural pores of the casing could be blocked by the large size tar particles from smoke, preventing the continued penetration of PAHs. The BaP content decreased and the moisture content increased progressively from the casing to the centre of the meat product. BaP mainly accumulated in the smoked casing, being four times in excess of the legal limit. This paper analyses the mechanism for preventing PAHs contamination during the process of smoking meat products.     

Polycyclic aromatic hydrocarbons in indoor and outdoor environments and factors affecting their concentrations

A highly sensitive analytical method for the simultaneous determination of 39 gaseous and particulate polycyclic aromatic hydrocarbons (PAHs) was used to determine the PAH composition of indoor and outdoor air in Shimizu, Japan. In both indoor and outdoor air, gaseous PAH concentrations were higher in summer than in winter, whereas particulate PAH concentrations were higher in winter than in summer. Correlation analysis indicated that indoor PAH compositions, especially the gaseous PAH composition, differed significantly from outdoor PAH compositions. Gaseous PAH concentrations indoors were significantly affected by insect repellents and heating sources. Particulate PAH concentrations indoors were significantly affected by cigarette smoking, the age and type (wood) of the house, and outdoor PAH concentrations. Inhalation risk associated with carcinogenic PAHs was estimated by using toxic equivalency factors based on the potency of benzo[a]pyrene (BaP). The carcinogenicity of the indoor PAH mixture was dominated by naphthalene followed by BaP and dibenz[a,h]anthracene.     

Polycyclic aromatic hydrocarbons (PAH) in chocolate on the German market

Benzo[a]anthracene (BaA), chrysene (CHR), cyclopenta[c,d]pyrene (CPP), 5-methylchrysene (5MC), benzo[b]fluoranthene (BbF), benzo[k]fluoranthene (BkF), benzo[j]fluGoranthene (BjF), benzo[a]pyrene (BaP), dibenzo[a,h]anthracene (DhA), indeno[1,2,3-cd]pyrene (IcP), benzo[g,h,i]perylene (BgP), dibenzo[a,l]pyrene (DlP), dibenzo[a,e]pyrene (DeP), dibenzo[a,i]pyrene (DiP) and dibenzo[a,h]pyrene (DhP), the 15 SCFPAH, assessed to be relevant as well as benzo[c]fluorene (BcL) recommended by the European Food Safety Authority (EFSA), were analysed in different types of chocolate. The sample preparation included accelerated solvent extraction (ASE), size exclusion chromatography (SEC) and solid phase chromatography using small silica gel columns. The individual PAH were separated by gas chromatography using a VF-17ms GC column and detected by high resolution mass spectrometry (HRMS). The investigation of 40 samples of various types of chocolate with different cocoa contents resulted in a median benzo[a]pyrene (BaP) content of 0.22 μg/kg. Furthermore, the results showed a linear correlation between the content of BaP and the sum content of the 16 priority PAH. Therefore, the analysis of BaP as a leading substance seems to be suitable to estimate the PAH contamination in chocolate.

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Zusammenfassung:  Für Bestimmung der 15+1 von der EU als priorit?r eingestuften PAK in verschiedenen Schokoladen wurde eine Analysenmethode bestehend aus beschleunigter L?sungsmittelextraktion (ASE), Gelpermeationschromatographie (GPC) und Nachreinigung an einer Minikieselgels?ule verwendet. Die Identifizierung und Quantifizierung der einzelnen Verbindungen erfolgte nach gaschromatographischer Trennung mit dem hochaufl?senden Massenspektrometer unter Verwendung einer VF-17ms GC-S?ule. Die Untersuchung von 40 Schokoladenproben mit verschiedenen Kakaogehalten erbrachte im Median einen Gehalt an Benzo[a]pyren (BaP) von 0,22 μg/kg. Es zeigte sich weiterhin eine enge Korrelation des BaP-Gehalts vom Gesamtgehalt der 15+1 EU-PAK. über die Leitsubstanz BAP l?sst sich somit der Gesamtgehalt der 15+1 EU-PAK durch die alleinige Bestimmung von BaP in Schokolade absch?tzen.

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Received: February 10, 2009; accepted: February 25, 2009.     

Milk and urine excretion of polycyclic aromatic hydrocarbons and their hydroxylated metabolites after a single oral administration in ruminants

The aim of this study was to establish the transfer of phenanthrene, pyrene, and benzo[a]pyrene and their major hydroxylated metabolites to milk and to urine after a single oral administration (100 mg per animal of each compound) in 4 lactating goats. Detection and identification of the analytes (native compounds, 1-OH pyrene, 3-OH phenanthrene, 3-OH benzo[a]pyrene) were achieved using gas chromatography-mass spectrometry. Benzo[a]pyrene, phenanthrene, and pyrene were rapidly detected in the plasma stream, whereas 1-OH pyrene and 3-OH phenanthrene appeared later in plasma. These data suggest that pyrene and phenanthrene are progressively metabolized within the organism. Recovery rates of pyrene and phenanthrene in milk over a 24-h period appeared to be very low (0.014 and 0.006%, respectively), whereas the transfer rates of their corresponding metabolites were significantly higher: 0.44% for 1-OH pyrene and 0.073% for 3-OH phenanthrene. Recovery rates in urine were found to be higher (1 to 10 times) than recovery rates in milk. The 1-OH pyrene was found to be the main metabolite in urine as well as in milk. Thus, as has been established for humans, 1-OH pyrene could be considered as a marker of ruminant exposure to polycyclic aromatic hydrocarbons. Because 1-OH pyrene and 3-OH phenanthrene were measured in milk (unlike their corresponding native molecules), metabolites of polycyclic aromatic hydrocarbons should be taken into consideration when evaluating the safety of milk. Benzo[a]pyrene and 3-OH benzo[a]pyrene were (less than 0.005%) transferred to milk and urine in very slight amounts. This very limited transfer rate of both compounds suggests a low risk of exposure by humans to benzo[a]pyrene or its major metabolite from milk or milk products.     

Survey of polycyclic aromatic hydrocarbons of vegetable oils and oilseeds by GC-MS in China

There is a lack of information regarding the occurrence and content of contamination of polycyclic aromatic hydrocarbon (PAH) in edible vegetable oils and oilseeds used for oil production in China. By combining the advantages of ultrasound-assisted extraction, low temperature separation and silica SPE purification, a method for the determination of the USEPA, 16 PAHs was developed based on GC-MS to fill this gap. The method recoveries for oils and oilseeds were 84.4–113.8% and 84.3–115.3%, respectively. The LODs and LOQs for 16 PAHs were ranged from 0.06–0.17 and 0.19–0.56 μg kg^–1, respectively. Based on the established method, PAH concentrations in 21 edible oils and 17 oilseeds were determined. Almost all the PAHs were found in all the samples tested, especially the light PAHs (LPAHs). Three oil samples exceeded the maximum level of 10 μg kg^–1 for BaP set by China. However, five and six oil samples, respectively, exceeded the maximum limits of 2 and 10 μg kg^–1 set for BaP and PAH4 by the European Union. The concentrations of PAH16 in oilseed samples were 1.5 times higher than corresponding oil samples. The relationships between PAH4 and PAH8, PAH4 and PAH16 as well as PAH8 and PAH16 indicates that PAH4 is a sufficient surrogate for the contamination level of PAHs in edible oils when compared with PAH8.     

Determination of polycyclic aromatic hydrocarbons (PAHs) in commonly consumed Nigerian smoked/grilled fish and meat

Smoking and/or grilling, when carried out with traditional methods involving direct contact with wood combustion fumes, is responsible for high contamination levels with carcinogenic polycyclic aromatic hydrocarbons (PAHs). The aim of this work was to investigate the PAH content of different smoked or grilled meat and fish products commonly consumed in Nigeria. A rapid method involving microwave-assisted saponification and simultaneous extraction followed by solid-phase extraction (SPE), high-performance liquid chromatography (HPLC) separation and spectrofluorometric detection was employed. Samples that were smoked or grilled using traditional systems, which use a wood fire, were heavily contaminated with benzo[a]pyrene (BaP) at levels ranging from 2.4 to 31.2 µg kg^?1 wet weight. Considerably lower contamination levels were found in samples smoked or grilled in the laboratory using a charcoal fire (BaP from 0.7 to 2.8 µg kg^?1 wet weight). The health risk associated with a daily consumption of 100 g of these products was also evaluated using the margin of exposure (MOE) approach. MOE values lower than 10,000 were obtained for all smoked/grilled commercial samples, indicating a potential concern for consumer health.     

Analytical chemistry,formation, mitigation,and risk assessment of polycyclic aromatic hydrocarbons: From food processing to in vivo metabolic transformation

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the air, oils, water, and food products we encounter every day. Among these exposures, food consumption is a major route of PAH exposure for nonsmokers. The PAH dietary exposure levels vary among different countries; however, many studies have shown PAH exposure to be highly concerning to human health. The levels of PAH contamination in food are mainly influenced by processing procedures and cooking methods, and they could be attenuated by modifying cooking procedures and adding antioxidant-rich marinades. Several PAHs have toxic, mutagenic, and carcinogenic properties. The PAH benzo[a]pyrene (BaP) is particularly regarded as carcinogenic. There are three major metabolism pathways for PAHs, and the final products can bind to DNA, thus exerting mutagenic effects. Biological monitoring through the use of biomarkers is necessary for comprehensive and accurate risk assessments of human PAH exposure. It is important to reduce dietary PAH exposure and to implement reasonable and effective risk management strategies to reduce PAH levels in food to improve public health.     

Polycyclic aromatic hydrocarbons (PAHs) in yerba mate (Ilex paraguariensis) from the Argentinean market

Polycyclic aromatic hydrocarbons (PAHs) occurrence in 50 samples marketed in the main supermarkets from Argentina was surveyed. A high performance liquid chromatography (HPLC) method was applied with fluorescence detection (FLD) and UV—VIS diodes array detector (DAD) for the analysis of 16 PAHs in “yerba mate” (Ilex paraguariensis), with recoveries higher than 89% and limits of detection and quantification lower than that found by other methodologies in previous studies. Contamination expressed as the sum of 16 analysed PAHs ranged between 224.6 and 4449.5 μg kg^?1 on dry mass. The contamination expressed as PAH4 (sum of benzo(a)pyrene, chrysene, benzo(a)anthracene and benzo(b)fluoranthene) varied between 8.3 and 512.4 μg kg^?1. The correlation coefficient for PAH2 (sum of benzo(a)pyrene and chrysene) and PAH4 groups was 0.99, for PAH2 and PAH8 (sum of benzo(a)pyrene, chrysene, benzo(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(g,h,i)perylene, dibenzo(a,h)anthracene and indeno(1,2,3cd) pyrene) 0.97 and for PAH4 and PAH8 0.98.     

A novel method for the rapid detection of benzo(a)pyrene in liquid milk by dimethyl sulfoxide selectively enhanced synchronous fluorescence spectrometry

Based on the high solubility efficiency and strong fluorescence response of benzo(a)pyrene (BaP) in dimethyl sulfoxide in combination with the high-performance derivative constant-energy synchronous fluorescence spectroscopic (DCESFS) technique, a simple, sensitive and economic method was developed for the determination of BaP in liquid milk. This method comprises ultrasound-assisted solvent extraction, solvent replacement and DCESFS detection. No saponification or other tedious clean-up procedures were needed. The recoveries of BaP in different milk samples were greater than 82%. Detection limits in full- and low-fat milk were 0.03 and 0.04 μg kg^–1, respectively.     

Polycyclic aromatic hydrocarbons in smoked fish – a critical review

Among hundreds of components, wood smoke also contains at least 100 polycyclic aromatic hydrocarbons (PAH) and their alkylated derivatives. Many of them are carcinogenic. Benzo[α]pyrene (BaP) is regarded as a marker of the carcinogenic PAH in smoke and smoked fish, although in olive residual oil the maximum level of 2 μg/kg for each of the eight most carcinogenic PAHs, including BaP, has been set. Contemporary analytical procedures based on extraction of the hydrocarbons from the matrix, clean-up procedure, separation by gas chromatography (GC) or high performance liquid chromatography (HPLC), followed by detection and quantification by mass spectrometry (MS) or fluorescence detectors (FLD), respectively, make it possible to determine individual PAH in smoked foods at concentrations of the order of 0.1 μg/kg or even 0.01 μg/kg. Heavily smoked fish from traditional kilns, especially their outer parts, may contain up to about 50 μg BaP/kg wet weight, while the meat of mild hot-smoked fish, from smokehouses supplied with conditioned wood smoke from external generators, contains only about 0.1 μg/kg, or even less. Some older data on the contents of BaP in smoked fish should be treated with caution, if the analytical procedures used did not guarantee unequivocal separation and identification of the individual PAH.     

Concentrations and health hazards of polycyclic aromatic hydrocarbons in selected commercial brands of milk

The concentrations and profiles of polycyclic aromatic hydrocarbons (PAHs) were determined in twenty popular commercial brands of milk in the Nigerian market after saponification with ethanolic KOH and cyclohexane extraction and clean up using a gas chromatography with flame ionization detection. The concentrations of the Σ16 PAHs in these brands of milk ranged from 15.6 to 1,711.8 μg kg^?1. The dominant PAH compounds in these brands of milk were 3-and-4-rings PAHs. The dietary intake of BaP, PAH2, PAH4 and PAH8 were 0–53.9 and 0–369.6 ng kg^?1 bw day^?1 respectively. Using these indicators for occurrence and effects (BaP, PAH2, PAH4 and PAH8) PAHs in food, the margin of exposure were <10,000 in 15–30 % of the brands.     

Relationship between total polar components and polycyclic aromatic hydrocarbons in fried edible oil

ABSTRACT

Deep-fried dough sticks (a Chinese traditional breakfast) were fried individually in peanut, sunflower, rapeseed, rice bran, soybean and palm oil without any time lag for 32 h (64 batches fried, each for 30 min) and fried oil samples were obtained every 2 h. The frying-induced changes in the levels of total polar compounds (TPC) and polycyclic aromatic hydrocarbons (PAHs) were investigated by edible oil polar compounds (EOPC) fast separation chromatographic system and gas chromatography-mass spectrometry (GC-MS), respectively. The correlations were analysed of TPC with benzo[a]pyrene (BaP), TPC and PAH4 (benzo[a]anthracene, chrysene, benzo[b]fluoranthene and benzo[a]pyrene) as well as TPC with PAH16 (USEPA 16 PAHs). The results revealed that the levels of TPC and PAHs in fried oil considerably increased with frying time, and the type of oil affected their formation, which could inform the choice of oil for frying. The total BaP equivalents (∑BaPeq) concentrations in fresh oil and in oil whose TPC exceeded 27% were 2.14–13.48 and 5.78–10.80 μg kg^–1, respectively, which means that the carcinogenic potency of frying oil was more pronounced than that of fresh oil. In addition, the TPC concentration was significantly correlated with the concentrations of the sum of the 16 PAHs, PAH4 and BaP, so that the levels of PAHs could be predicted according to the levels of TPC in fried oil. In European standards, the rejection point for TPC in frying oil should be recalculated when considered PAHs. In all, the concentration of PAHs is a vital factor for ensuring the safety of frying oil.     

不同植物油制取工艺对毛油中多环芳烃含量的影响

以花生仁、芝麻、油菜籽为原料,采用不同工艺分别制取毛油,并对毛油中多环芳烃(PAHs)含量进行检测分析,探究制油工艺对毛油中PAHs含量的影响。结果表明:6个浸出毛油样品中Ba P、PAH4、PAH16平均含量分别是6个压榨毛油样品的1.53、1.45、1.08倍,说明PAHs在浸出溶剂正己烷中有很好的溶解度,因此油籽无论脱皮与否所制取浸出毛油中PAHs含量均高于压榨毛油;6个脱皮油籽所制取毛油中Ba P、PAH4、PAH16平均含量分别是未脱皮油籽毛油的1.51、1.61、1.53倍,即无论是压榨法还是浸出法,脱皮油籽所制取毛油中PAHs含量均高于未脱皮油籽毛油。这可能是因为种皮主要成分为粗纤维,而PAHs的亲脂性使其更容易富集在种仁中。     

Benzo[a]pyrene and total polycyclic aromatic hydrocarbons (PAHs) levels in vegetable oils and fats do not reflect the occurrence of the eight genotoxic PAHs

Concentrations of polycyclic aromatic hydrocarbons (PAHs) were determined in 115 samples of olive oil (extra virgin olive oil, virgin olive oil, olive oil, pomace olive oil and blended olive oil), cooking oil (corn oil, sunflower oil, sesame oil, palm olein oil, soya oil, canola oil, mustard oil, peanut oil and mixed vegetable oil) and fat (butter and table margarine) collected from retail stores in Kuwait. Carcinogenic benzo[a]pyrene (BaP) was detected in 43% of the samples analyzed. Benz[a]anthracene and chrysene were detected in 37 and 45% of the samples, respectively, that did not contain BaP. Of the individual non-carcinogenic PAHs, naphthalene showed the highest mean concentration (14 µg kg^?1), while for the carcinogenic PAHs, BaP (0.92 µg kg^?1) and chrysene (0.87 µg kg^?1) showed the highest mean values. Approximately 20% of the samples within the olive oil and cooking oil sub-categories exceeded the EU maximum tolerable limit for BaP, with the highest level of 6.77 and 11.1 µg kg^?1, respectively. For the fat sub-category, 9% of the samples exceeded the tolerance limit, with the highest level of 3.67 µg kg^?1. The Kuwaiti general population's dietary exposure to the genotoxic PAHs (PAH8: benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene, dibenz[a,h]anthracene and benzo[ghi]perylene) was estimated to be 196 ng day^?1 (3.3 ng kg^?1 bw day^?1, assuming an average adult body weight of 60 kg). Results indicated that PAH8 and BaP_eq (total sum benzo[a]pyrene equivalents) are more reliable measures of the concentrations of other carcinogenic PAHs in oil and fat samples, while BaP and PAHs alone are not good indicators of the occurrence or degree of contamination by carcinogenic PAHs in these food products.     

Occurrence of polycyclic aromatic hydrocarbons in artisanal Palmero cheese smoked with two types of vegetable matter

Palmero cheese is a fresh smoked cheese from the Isle of Palma (Canary Islands), manufactured with goat's milk. To guarantee its safety, the occurrence of polycyclic aromatic hydrocarbons (PAH) in artisanal Palmero cheese smoked with 2 types of vegetable matter (almond shells and dry prickly pear) was studied. The determination of PAH includes extraction and clean-up steps, followed by separation, identification, and quantification of PAH by gas chromatography-mass spectrometry in selected ion-monitoring mode. The most abundant PAH are those with 2 and 3 aromatic rings. Although the highest total PAH concentrations corresponded to the cheeses smoked with almond shells, the degree of PAH contamination of the cheeses studied was lower than that found in other cheeses smoked in the traditional way. The nature of the vegetable material used for smoking seemed to have an influence on the type of PAH formed, especially on alkylderivatives and some light PAH. However, despite the artisanal, and consequently variable, production process of these cheeses, many similarities have been found among their PAH profiles. In fact, relatively constant relationships are observed between the concentrations of certain pairs of PAH. Benzo(a)pyrene was only present in 2 samples, and in much lower concentrations than the maximum allowed legal limits. Therefore, according to the results obtained, it appears that it is possible to obtain a safe product without renouncing the artisanal character or the sensory properties of this type of cheese.     

Polycyclic aromatic hydrocarbons and lead in roadside lettuce and rye grain

Thirty-eight samples of lettuce and three samples of rye from an experimental site close to a highway were analysed for 20 polycyclic aromatic hydrocarbons (PAH) and lead. The lettuce plants were grown 8–65 m from the road and collected after 5,9 and 11 weeks of exposure. The levels of benzo[a]pyrene (BaP) and lead varied from 0.1 to 1.3 μg kg^?1 and from 0.18 to 1.6 mg kg^?1, respectively. The plants grown close to the road and with long exposure times showed the highest levels. The positive gradients for PAH and lead with exposure time and closeness to the road were nearly identical, but in different concentration ranges. Lettuce plants grown in a cold frame showed lower levels than those grown in the open. In rye sampled at 7–25 m from the road, BaP was not detected and lead levels ranged from 0.07 to 0.11 mg kg^?1. The results suggest that the Swedish National Food Administration/National Environmental Protection Board recommendations, i.e. not to grow leafy vegetables closer than 25 m from roads with intense traffic, are sufficient at traffic flows of up to 12 000 vehicles per day.