This article was downloaded by: [Yale University Library] On: 21 August 2013, At: 17:28 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Food Additives & Contaminants Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tfac19
Migration of plasticizer from poly(vinyl chloride) milk tubing a
a
L. Castle , J. Gilbert & T. Eklund
b
a
Food Science Laboratory, Ministry of Agriculture, Fisheries and Food, Colney Lane, Norwich, NR4 7UQ, UK b
Norwegian Dairies Association, Breigt 10, Vateraland, Oslo, 0134, Norway Published online: 10 Jan 2009.
To cite this article: L. Castle , J. Gilbert & T. Eklund (1990) Migration of plasticizer from poly(vinyl chloride) milk tubing, Food Additives & Contaminants, 7:5, 591-596, DOI: 10.1080/02652039009373924 To link to this article: http://dx.doi.org/10.1080/02652039009373924
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/ page/terms-and-conditions
FOOD ADDITIVES AND CONTAMINANTS, 1990, VOL. 7, NO. 5, 5 9 1 - 5 9 6
Migration of plasticizer from poly(vinyl chloride) milk tubing L. CASTLE†, J. GILBERT† and T. EKLUND‡ † Ministry of Agriculture, Fisheries and Food, Food Science Laboratory, Colney Lane, Norwich NR4 7UQ, UK; ‡Norwegian Dairies Association, Breigt 10, Vateraland, 0134 Oslo, Norway
Downloaded by [Yale University Library] at 17:28 21 August 2013
(Received 22 February 1990; accepted 30 March 1990) Milk samples were collected from a dairy in Norway at various stages of the milking process in order to assess the extent of migration of di(2-ethyl hexyl)phthalate (DEHP) from plasticized tubing used in commercial milking equipment. In control milk samples obtained by hand milking, DEHP contamination was below 5 µg/kg, whilst for machine milking, concentrations in the milking chamber for each individual cow averaged 30 µg/kg and rose to 50 µg/kg in the central collecting tank. Retail pasturized skimmed milk samples from Norway were found to contain 20 µg/kg DEHP, and two retail cream samples contained 1200 and 1400 µg/kg of DEHP, reflecting the association of plasticizer with the fat phase. Retail whole milks from the UK contained 35 µg/kg of DEHP. This contamination is believed to originate from environmental sources as DEHP plasticizer was not used in the milking equipment. Keywords: Migration; PVC milk tubing; di(2-ethylhexyl)phthalate; plasticizer; milking equipment
Introduction
Although for many years there has been considerable interest in the migration of plasticizers from plastics into biological materials, including foods (Giam and Wong 1987) , it is only relatively recently that, with improvements in analytical techniques, data have become available on the actual levels of contamination of retail packaged foodstuffs (Castle et al. 1987, 1988, Kozyrod and Ziaziaris, 1989). These studies have demonstrated that di(2-ethylhexyl)adipate (DEHA) employed in plasticized PVC can frequently be found at mg/kg levels in fatty foods, whilst di-(2ethylhexyl)phthalate (DEHP), although a ubiquitous environmental contaminant, is used to a lesser extent and at lower levels in food contact materials, and thus is a less widespread contaminant from packaging. In the UK, other than in closure seals for beverages, the use of DEHP in food packaging materials was found to be restricted to printing inks, where amounts from 2% to 8% are used in the formulations. Despite the printing being only on the outer surface of the packaging, which was not in direct contact with the food, it was nevertheless possible to detect DEHP contamination of, for example, confectionery and snack products at levels up to 1-8 mg/kg (Castle et al. 1989). Surveillance work carried out in Italy has indicated more widespread contamination of foods with DEHP at levels up to 6-75 mg/kg (Cocchieri, 1986). These findings confirmed earlier work from Japan where DEHP levels from 0-01 to 16*3 mg/kg in retail foods were reported (Tomita et al. 1977), both groups noting contamination being particularly associated with © Crown Copyright 1990
Downloaded by [Yale University Library] at 17:28 21 August 2013
592
L. Castle et al.
dried foods such as soups. The latter workers attributed this to migration of DEHP from the printing on the package. Although another potential source of DEHP contamination is the use of plasticized plastic tubing in dairies for milking, and for bulk transfer from tankers, there have been few studies to establish the true extent of the problem in real situations. Wildbrett (1973) demonstrated migration of 70 mg/1 of DEHP from PVC tubing (containing 5% plasticizer) during total immersion of the tubing in milk for 24 h at 56°C, whilst Ruuska et al. (1987) found migration of 1-9-5-0 mg/1 from tubing containing 40% plasticizer when in contact from 1 to 6 days with milk at 40°C. Mueller and Bradley (1980) have reported migration of DEHP from tubing into milk at 38°C to occur at the significantly lower levels of 0-1-4-3 /tg/1 per day, but this again was from static migration experiments (4 h) and it is difficult to see how this relates to the real situation of actual usage. In contrast Leoni et al. (1981) collected milk samples at a dairy and showed that, for samples collected by hand from the cows, DEHP was not detectable in the milk, whilst using machine milking with plastic tubing and rubber components levels of DEHP from 0-04 to 0-11 mg/kg were detected. Domestic retail milks collected from a wide range of locations contained DEHP ranging from 0-8 to 1-72 mg/kg, whilst butter contained 0-1 to 5-6 mg/kg (Leoni et al. 1981). These results agree with another Italian survey which reported DEHP levels averaging 0-21 mg/kg with a maximum of 1-28 mg/kg in milks and averaging 1-08 mg/kg with a maximum of 4-57 mg/kg in cheeses (Cocchieri, 1986). In this paper we report work carried out to assess the true extent of DEHP contamination of milk, in this case obtained from Norway where this plasticizer was widely used in commercial milk-handling equipment. Particular care was taken in the collection of samples to ensure freedom from adventitious contamination. Work was also undertaken to attempt to cross-check the results on migration of DEHP into milk by the analysis of both new and extensively used milk tubing itself, to detect the extent of any loss of plasticizer. In contrast to Norway, it has been established that the U.K. dairy industry uses tubing which does not contain plasticizers, except in bulk transfer between tankers and storage tanks where PVC tubing plasticized with di(isodecyl)phthalate (DIDP) rather than DEHP is used (MAFF 1987). The isomeric nature of DIDP means there are considerable analytical difficulties associated with its direct determination in foods. However, as the time during which refrigerated milk is in contact with the tubing is brief, migration is expected to be low. Experimental Materials Samples of raw milk were collected by hand milking of cows at a Norwegian dairy and by interception at various stages in the milking process. Samples were placed directly in 125 ml glass bottles (Supelco Ltd) and sealed with PTFE-faced septa and screw caps. Samples were delivered by hand to the analytical laboratory within 2 days of collection and stored at -18°C prior to analysis. Retail milk and cream samples were locally purchased in Oslo and Norwich. Two samples of flexible PVC tubing of the 'Tygon type' were supplied from Norway, these being new tubing and that which had been used in a dairy and was due for replacement.
Plasticizer migration from milk tubing
593
Downloaded by [Yale University Library] at 17:28 21 August 2013
DEHP plasticizer standard was a commercial sample (Genomoll 100) obtained from Hoechst, and the deuterated internal standard (d4-DEHP) was available from an earlier study (Castle et al. 1988). All solvents used in the analysis were HPLC-grade (Rathburn Chemicals Ltd, Walkerburn, Scotland, UK) and were demonstrated to be free of plasticizer contamination. Precautions As DEHP is a ubiquitous environmental contaminant, and in particular can be a problem in the laboratory due to contamination of chemicals and reagents, it was necessary to take extensive precautions for cleaning of glassware, checking for possible sources of contamination and running frequent control blank samples. All glassware was washed twice with methanol, followed by washing twice with hexane immediately prior to use. All solvents were checked for DEHP contamination by the evaporation of 100 ml to near dryness and analysis by GC. Analysis of milk Frozen milk samples were allowed to warm to room temperature, vigorously shaken to ensure uniform mixing and an accurately weighed subsample (10 g) was poured into a 20 ml glass vial. This was followed by the addition of methanol (5 ml), hexane (3 ml), potassium hydroxide (ca. 300 mg) and d4-DEHP internal standard (20/*l of a 0-59 mg/ml solution in hexane). The vials were capped, shaken for 30 min on an orbital shaker and then centrifuged at 3000 rpm for 5 min to effect phase separation. The upper phase was transferred by pipette to a pre-weighed vial, the solvent removed by evaporation under a stream of nitrogen and the resultant fat was weighed. The fat was redissolved in 1:1 dichloromethane-cyclohexane (1-5 ml) and then separation of the DEHP from the fat was performed by automated size-exclusion chromatography as described previously (Shepherd 1984). A 40 X 1-5 cm column packed with Biobeads SX3 was employed at a flow rate of 0-5 ml/min, injections were of 0*25 ml (containing typically 50-75 mg of fat) and the fraction eluting 15-18 ml from injection and containing DEHP was collected from the column. The fraction from the column was evaporated to a small volume (200-300^1) under nitrogen at 60°C, and stored at - 18°C in a sealed vial prior to GC/MS analysis. Analysis of PVC tubing Samples of the PVC tubing (15-40 mg), taken as cross-sections or as slices from internal or external surfaces, were dissolved in tetrahydrofuran (3 ml) by allowing them to stand overnight. Internal standard (1 ml of a 10 mg/ml solution of tetracosane in chloroform) was added and the polymer precipitated by the addition of chloroform (6 ml) followed by dropwise addition of methanol (2 ml). After centrifugation at 3000 rpm for 1 min the supernatent was analysed by capillary GC. A Carlo Erba 4160 capillary GC was employed operating with split injection (20:1) and using a 25 m x 0-22 mm i.d. fused silica CPSIL 5CB (0-12 jtm film thickness) column at 240°C (Chrompak, UK). Gas chromatographyI mass spectrometry Combined GC/MS was carried out using a Carlo Erba 4160 GC coupled directly to a VG 12000 quadrupole mass sectrometer as described previously (Castle
594
L. Castle et al.
et al. 1988) with quantification based on peak area ratios from a calibration curve using the deuterated internal standard.
Downloaded by [Yale University Library] at 17:28 21 August 2013
Results and discussion Analytical procedure The analytical procedure was designed to minimize the number of items of glassware employed, and to use minimal quantities of solvent, thus limiting opportunities for DEHP contamination during the analysis itself. Preliminary work indicated that with care it was possible to monitor DEHP in milk samples to a limit of 5 jtg/kg. Using the stable isotope dilution procedure it was not necessary to correct for recovery losses, but it was shown in preliminary spiking experiments that the procedure gave a recovery of better than 90%. Calibration curves were linear through the origin, and for spiking experiments with DEHP over the range 10-100 /ig/kg using retail milk samples the found/added values averaged 103 ± 3%. DEHP in milk from a Norwegian dairy The results for DEHP concentrations in milk samples taken from a dairy in Norway are shown in table 1. Levels of contamination in the control samples obtained by hand milking were consistently low (
Food Additives & Contaminants Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tfac19
Migration of plasticizer from poly(vinyl chloride) milk tubing a
a
L. Castle , J. Gilbert & T. Eklund
b
a
Food Science Laboratory, Ministry of Agriculture, Fisheries and Food, Colney Lane, Norwich, NR4 7UQ, UK b
Norwegian Dairies Association, Breigt 10, Vateraland, Oslo, 0134, Norway Published online: 10 Jan 2009.
To cite this article: L. Castle , J. Gilbert & T. Eklund (1990) Migration of plasticizer from poly(vinyl chloride) milk tubing, Food Additives & Contaminants, 7:5, 591-596, DOI: 10.1080/02652039009373924 To link to this article: http://dx.doi.org/10.1080/02652039009373924
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/ page/terms-and-conditions
FOOD ADDITIVES AND CONTAMINANTS, 1990, VOL. 7, NO. 5, 5 9 1 - 5 9 6
Migration of plasticizer from poly(vinyl chloride) milk tubing L. CASTLE†, J. GILBERT† and T. EKLUND‡ † Ministry of Agriculture, Fisheries and Food, Food Science Laboratory, Colney Lane, Norwich NR4 7UQ, UK; ‡Norwegian Dairies Association, Breigt 10, Vateraland, 0134 Oslo, Norway
Downloaded by [Yale University Library] at 17:28 21 August 2013
(Received 22 February 1990; accepted 30 March 1990) Milk samples were collected from a dairy in Norway at various stages of the milking process in order to assess the extent of migration of di(2-ethyl hexyl)phthalate (DEHP) from plasticized tubing used in commercial milking equipment. In control milk samples obtained by hand milking, DEHP contamination was below 5 µg/kg, whilst for machine milking, concentrations in the milking chamber for each individual cow averaged 30 µg/kg and rose to 50 µg/kg in the central collecting tank. Retail pasturized skimmed milk samples from Norway were found to contain 20 µg/kg DEHP, and two retail cream samples contained 1200 and 1400 µg/kg of DEHP, reflecting the association of plasticizer with the fat phase. Retail whole milks from the UK contained 35 µg/kg of DEHP. This contamination is believed to originate from environmental sources as DEHP plasticizer was not used in the milking equipment. Keywords: Migration; PVC milk tubing; di(2-ethylhexyl)phthalate; plasticizer; milking equipment
Introduction
Although for many years there has been considerable interest in the migration of plasticizers from plastics into biological materials, including foods (Giam and Wong 1987) , it is only relatively recently that, with improvements in analytical techniques, data have become available on the actual levels of contamination of retail packaged foodstuffs (Castle et al. 1987, 1988, Kozyrod and Ziaziaris, 1989). These studies have demonstrated that di(2-ethylhexyl)adipate (DEHA) employed in plasticized PVC can frequently be found at mg/kg levels in fatty foods, whilst di-(2ethylhexyl)phthalate (DEHP), although a ubiquitous environmental contaminant, is used to a lesser extent and at lower levels in food contact materials, and thus is a less widespread contaminant from packaging. In the UK, other than in closure seals for beverages, the use of DEHP in food packaging materials was found to be restricted to printing inks, where amounts from 2% to 8% are used in the formulations. Despite the printing being only on the outer surface of the packaging, which was not in direct contact with the food, it was nevertheless possible to detect DEHP contamination of, for example, confectionery and snack products at levels up to 1-8 mg/kg (Castle et al. 1989). Surveillance work carried out in Italy has indicated more widespread contamination of foods with DEHP at levels up to 6-75 mg/kg (Cocchieri, 1986). These findings confirmed earlier work from Japan where DEHP levels from 0-01 to 16*3 mg/kg in retail foods were reported (Tomita et al. 1977), both groups noting contamination being particularly associated with © Crown Copyright 1990
Downloaded by [Yale University Library] at 17:28 21 August 2013
592
L. Castle et al.
dried foods such as soups. The latter workers attributed this to migration of DEHP from the printing on the package. Although another potential source of DEHP contamination is the use of plasticized plastic tubing in dairies for milking, and for bulk transfer from tankers, there have been few studies to establish the true extent of the problem in real situations. Wildbrett (1973) demonstrated migration of 70 mg/1 of DEHP from PVC tubing (containing 5% plasticizer) during total immersion of the tubing in milk for 24 h at 56°C, whilst Ruuska et al. (1987) found migration of 1-9-5-0 mg/1 from tubing containing 40% plasticizer when in contact from 1 to 6 days with milk at 40°C. Mueller and Bradley (1980) have reported migration of DEHP from tubing into milk at 38°C to occur at the significantly lower levels of 0-1-4-3 /tg/1 per day, but this again was from static migration experiments (4 h) and it is difficult to see how this relates to the real situation of actual usage. In contrast Leoni et al. (1981) collected milk samples at a dairy and showed that, for samples collected by hand from the cows, DEHP was not detectable in the milk, whilst using machine milking with plastic tubing and rubber components levels of DEHP from 0-04 to 0-11 mg/kg were detected. Domestic retail milks collected from a wide range of locations contained DEHP ranging from 0-8 to 1-72 mg/kg, whilst butter contained 0-1 to 5-6 mg/kg (Leoni et al. 1981). These results agree with another Italian survey which reported DEHP levels averaging 0-21 mg/kg with a maximum of 1-28 mg/kg in milks and averaging 1-08 mg/kg with a maximum of 4-57 mg/kg in cheeses (Cocchieri, 1986). In this paper we report work carried out to assess the true extent of DEHP contamination of milk, in this case obtained from Norway where this plasticizer was widely used in commercial milk-handling equipment. Particular care was taken in the collection of samples to ensure freedom from adventitious contamination. Work was also undertaken to attempt to cross-check the results on migration of DEHP into milk by the analysis of both new and extensively used milk tubing itself, to detect the extent of any loss of plasticizer. In contrast to Norway, it has been established that the U.K. dairy industry uses tubing which does not contain plasticizers, except in bulk transfer between tankers and storage tanks where PVC tubing plasticized with di(isodecyl)phthalate (DIDP) rather than DEHP is used (MAFF 1987). The isomeric nature of DIDP means there are considerable analytical difficulties associated with its direct determination in foods. However, as the time during which refrigerated milk is in contact with the tubing is brief, migration is expected to be low. Experimental Materials Samples of raw milk were collected by hand milking of cows at a Norwegian dairy and by interception at various stages in the milking process. Samples were placed directly in 125 ml glass bottles (Supelco Ltd) and sealed with PTFE-faced septa and screw caps. Samples were delivered by hand to the analytical laboratory within 2 days of collection and stored at -18°C prior to analysis. Retail milk and cream samples were locally purchased in Oslo and Norwich. Two samples of flexible PVC tubing of the 'Tygon type' were supplied from Norway, these being new tubing and that which had been used in a dairy and was due for replacement.
Plasticizer migration from milk tubing
593
Downloaded by [Yale University Library] at 17:28 21 August 2013
DEHP plasticizer standard was a commercial sample (Genomoll 100) obtained from Hoechst, and the deuterated internal standard (d4-DEHP) was available from an earlier study (Castle et al. 1988). All solvents used in the analysis were HPLC-grade (Rathburn Chemicals Ltd, Walkerburn, Scotland, UK) and were demonstrated to be free of plasticizer contamination. Precautions As DEHP is a ubiquitous environmental contaminant, and in particular can be a problem in the laboratory due to contamination of chemicals and reagents, it was necessary to take extensive precautions for cleaning of glassware, checking for possible sources of contamination and running frequent control blank samples. All glassware was washed twice with methanol, followed by washing twice with hexane immediately prior to use. All solvents were checked for DEHP contamination by the evaporation of 100 ml to near dryness and analysis by GC. Analysis of milk Frozen milk samples were allowed to warm to room temperature, vigorously shaken to ensure uniform mixing and an accurately weighed subsample (10 g) was poured into a 20 ml glass vial. This was followed by the addition of methanol (5 ml), hexane (3 ml), potassium hydroxide (ca. 300 mg) and d4-DEHP internal standard (20/*l of a 0-59 mg/ml solution in hexane). The vials were capped, shaken for 30 min on an orbital shaker and then centrifuged at 3000 rpm for 5 min to effect phase separation. The upper phase was transferred by pipette to a pre-weighed vial, the solvent removed by evaporation under a stream of nitrogen and the resultant fat was weighed. The fat was redissolved in 1:1 dichloromethane-cyclohexane (1-5 ml) and then separation of the DEHP from the fat was performed by automated size-exclusion chromatography as described previously (Shepherd 1984). A 40 X 1-5 cm column packed with Biobeads SX3 was employed at a flow rate of 0-5 ml/min, injections were of 0*25 ml (containing typically 50-75 mg of fat) and the fraction eluting 15-18 ml from injection and containing DEHP was collected from the column. The fraction from the column was evaporated to a small volume (200-300^1) under nitrogen at 60°C, and stored at - 18°C in a sealed vial prior to GC/MS analysis. Analysis of PVC tubing Samples of the PVC tubing (15-40 mg), taken as cross-sections or as slices from internal or external surfaces, were dissolved in tetrahydrofuran (3 ml) by allowing them to stand overnight. Internal standard (1 ml of a 10 mg/ml solution of tetracosane in chloroform) was added and the polymer precipitated by the addition of chloroform (6 ml) followed by dropwise addition of methanol (2 ml). After centrifugation at 3000 rpm for 1 min the supernatent was analysed by capillary GC. A Carlo Erba 4160 capillary GC was employed operating with split injection (20:1) and using a 25 m x 0-22 mm i.d. fused silica CPSIL 5CB (0-12 jtm film thickness) column at 240°C (Chrompak, UK). Gas chromatographyI mass spectrometry Combined GC/MS was carried out using a Carlo Erba 4160 GC coupled directly to a VG 12000 quadrupole mass sectrometer as described previously (Castle
594
L. Castle et al.
et al. 1988) with quantification based on peak area ratios from a calibration curve using the deuterated internal standard.
Downloaded by [Yale University Library] at 17:28 21 August 2013
Results and discussion Analytical procedure The analytical procedure was designed to minimize the number of items of glassware employed, and to use minimal quantities of solvent, thus limiting opportunities for DEHP contamination during the analysis itself. Preliminary work indicated that with care it was possible to monitor DEHP in milk samples to a limit of 5 jtg/kg. Using the stable isotope dilution procedure it was not necessary to correct for recovery losses, but it was shown in preliminary spiking experiments that the procedure gave a recovery of better than 90%. Calibration curves were linear through the origin, and for spiking experiments with DEHP over the range 10-100 /ig/kg using retail milk samples the found/added values averaged 103 ± 3%. DEHP in milk from a Norwegian dairy The results for DEHP concentrations in milk samples taken from a dairy in Norway are shown in table 1. Levels of contamination in the control samples obtained by hand milking were consistently low (
