Z. Lebensm. Unters. Forsch. 170, 346-348 (1980) Zeitschrift fur

Lebensmittel- Untersuchung

und-Forschung (~) J. F. Bergmann Verlag 1980

Polychlorinated Biphenyl Compounds in Milk and Dairy Products

Roland Van Renterghem and Luc Devlaminck

Government Dairy Research Station, Brusselsesteenweg 370, B-9230 Melle, Belgium

Polychlorierte Biphenylverbindungen in Milch und Milcherzeugnissen

Zusammenfassung. Der Gehalt an polychlorierten Bi- phenylverbindungen wurde in 469 Milch- und Milcher- zeugnis-Proben bestimmt. Das Fett wurde extrahiert und fiber Aluminiumoxid gereinigt. Die Organochlor- pesticide und die PCB's wurden durch Chromatogra- phic fiber eine Silicagelkolonne getrennt. Die PCB's der gereinigten Extrakte wurden zu Dekachlorbiphenyl perchloriert und durch Gaschromatographie be- stimmt. Der durchschnittliche PCB-Gehalt der gesam- ten Muster betrug 0,18 mg pro kg Fett. Die Ergebnisse k6nnen mit denen der Nachbarl~inder verglichen wer- den und sind bedeutsam niedriger als die vorlfiufige FDA-Toleranz yon 1,5 mg pro kg Fett.

Summary. The PCB content of 469 milk and dairy product samples was determined. The fat was extracted and cleaned up through aluminium oxide. The or- ganochlorine pesticides and the PCBs were separated by chromatography through a silica gel column. The PCBs in the purified extracts were perchlorinated to de- cachlorobiphenyl and determined by gas chromatogra- phy. The mean PCB content of the samples investi- gated was 0.18 mg per kg fat. The results are compara- ble with those obtained in neighbouring countries and significantly lower than the interim FDA tolerance of 1.5 mg per kg fat.

products, and mostly found PCBs, although in small quantities.

As PCBs may be toxic to man, the presence of these compounds in the main source of intake, viz. food, is intensively investigated.

This study deals with the presence of PCBs in milk and dairy products.

Material and Methods

Sampling

During 1977 and 1978, a total of 469 samples of milk and dairy products were taken at regular intervals (Table 1).

The raw milk was sampled throughout Belgium, ac- cording to the production of the various areas.

The dairy products were sampled at the point of sale and were partly, as opposed to the raw milk, of foreign origin, especially cheese and baby food. The latter comprised only products containing milk pow- der.

Reagents

The reagents which should satisfy the purity requirements of a resi- due analysis, were: pentane, acetone, anhydrous sodium sulphate, antimony pentachloride, sodium hydrogen carbonate (10% solution in water), 20% hydrochloric acid, aluminium oxide (basic, activity degree I, before use deactivated with 10% of water) and silica gel (70- 230 mesh ASTM), before use activated for 15 h at 200 °C and cooled in a desiccator over P2Os).

The high chemical stability of polychlorinated biphenyl (PCB) compounds results in a very large environmental distribution.

Since 1966, in which year the presence of PCBs in fish and sea-birds was for the first time reported by Jen- sen [1], many researchers have investigated various

Equipment

High-speed mixer. - Kuderna-Danish concentrators of 500 ml with 5 ml graduated tubes. Chromatography tubes: approx. 50 cm long, inside diam. 8.0 + 0.5 ram. Separating funnels, 150 and 500 ml, with PTFE stop cocks. - Esterification tubes of hard glass, with useful ca- pacity of 15 ml. - Hewlett-Packard 5710 gas chromatograph with electron-capture detector (Ni 63); column: glass, 1.80 m, 3% SE 30 on gaschrom Q (80-100 mesh); carrier gas: argon/methane 95/5,

0044-3026/80/0170/0346/$1.00

R. Van Renterghem and L. Devlaminck: Polychlorinated Biphenyl Compounds in Milk and Dairy Products 347

Table 1. PCB contents of milk and dairy products in Belgium

Products Number Content mg/kg fat of samp!es Minimmn Mean Maximum Median

value

Raw milk Farm 30 0.05 0.21 0.69 0.18 samples Bulk 179 0.02 0.18 0.44 0.17 samples

Consumer 79 0.06 0.19 0.43 0.19 milk

Cheese 58 0.01 0.14 0.58 0.10 Butter 55 0.02 0.15 0.66 0.12 Baby food 68 0.05 0.25 0.80 0.24

containing milk powder

Total 469 0.01 0.18 0.80 0.17

to a chromatography tube, previously rinsed with 25 ml pentane. A precise weight of fat (200-250 mg) is dissolved in a few ml pentane and quantitatively added to the column. The column is eluted with the volume of pentane (80-100 ml) necessary to obtain a fl-hexa- chlorocyclohexane recovery of at least 80% and a fat retention of at least 95%. The exact amount of pentane depends upon the activity of the aluminium oxide and is experimentally determined. The col- umn elute is concentrated to a few ml in a Kuderna-Danish concen- trator.

Separation on a Silica Gel Column

A wad of quartz wool, 5 g of activated silica gel and a few grams of anhydrous sodium sulphate are successively transferred to a chroma- tography tube, previously rinsed with 25 ml of pentane. The concen- trated elute from the aluminium oxide column is quantitatively trans- ferred to the silica gel column. The column is eluted with the volume of pentane (25-40 ml) necessary to obtain a recovery of at least 95% for Arochlor 1260 and a retention of at least 95% for pp'-DDE. The exact amount of pentane depends on the silica gel activity and is ex- perimentally determined. The column elute is concentrated to ap- prox. 1 mI in a Kuderna-Danish concentrator.

40 ml/min; temperatures: oven 265 °C, injector 300 °C, detector 350'C.

Procedure

Principle. The procedure is based mainly on the method of Greve and Grevenstuk [2].

The fat is extracted from the sample. The or- ganochlorine pesticides and the PCBs are separated from the fat on an aluminium oxide column. The PCBs, hexachlorobenzene, aldrin and heptachlor are separated from the other organochlorine compounds by chromatography on a silica gel column.

After perchlorination with antimony pentachloride, the PCBs are determined by gas chromatography as decachlorobiphenyl.

Fat Extraction

Milk andMilk Powder. 50 ml of milk or milk reconstituted from milk powder, are successively mixed with 200 ml of aceton and 100 ml of pentane. The mixture is transferred to a separating funnel; after phase separation the aqueous layer is removed. The organic phase is washed with 100 ml of water and dried over anhydrous sodium sul- phate. The solvent is then evaporated.

Butter. 5 g of butter is heated at approx. 50 °C and the fat is decanted through a coarse filter.

Cheese. An amount containing approx. 1 g of fat is macerated with a sufficient quantity of anhydrous sodium sulphate until a dry pow- der is obtained. After successive mixing with 200 ml of acetone and 100 ml of pentane, the mixture is transferred to a 500-ml separating funnel. After phase separation, the aqueous layer is removed. The or- ganic phase is washed with 100 ml of water and dried over anhydrous sodium sulphate. The solvent is then evaporated.

Separation on a Aluminium Oxide Column

A wad of quartz wool, 10 g of deactivated aluminium oxide and a few grams of anhydrous sodium sulphate are successively transferred

Perchlorination

The concentrated elute from the silica gel column is quantitatively transferred to an esterification tube and is evaporated to dryness in a flow of nitrogen at room temperature. After addition of 0.2 ml of antimony pentachloride, the tube is sealed, shaken and heated for 3 h at 180 °C. The tube is allowed to cool to room temperature and opened, and 3 ml of 20% HC1 are added. With regular shaking the tube is heated for 15 minutes at 60 °C. The contents are transferred to a 150-ml-separating funnei, the tube is rinsed with 3 ml of 20% HC1 and 2 x 15 ml of pentane. After shaking for 2 minutes the pentane layer is separated and the aqueous phase is twice extracted with 25 ml of pentane. The combined pentane phases are successively washed with 2 x 20 ml of water, 20 ml of 10% sodium hydrogen carbonate solution an 2 x 20 ml of water.

The pentane phase is dried over anhydrous sodium sulphate and concentrated to 1 ml in a Kuderna-Danish concentrator, 5 gl of this perchlorinated solution is injected into the gas chromatograph.

Quantitative Determination

For this purposes an Arochlor 1260 standard series is prepared (0 - 0.1 - 0.2 - 0.3 - 0.4 and 0.5 ppm) and treated in the same way as the samples, and a cali- bration graph can be drawn.

Results

The results recorded for each product are shown in Table 1.

For the purposes of comparison, recent data from neighbouring countries are shown in Table 2. Except for the results recorded in France, which partly refer to highly polluted areas, all mean contents vary between 0.1 and 0.4 mg per kg of fat.

Conclusion

The over-all PCB content of the samples investigated amounted to 0.18 mg per kg of fat. The median value, i.e. 0.17 mg per kg of fat, differed only slightly from the

348 R. Van Renterghem and L. Devlaminck: Polychlorinated Biphenyl Compounds in Milk and Dairy Products

Table 2. The PCB content of milk and dairy products in The Netherlands, France and West Germany

Country Product Number of Content mg/kg fat samples

Mean Range Year Reference

The Netherlands

France

West-Germany

Milk 315 0.16 a 0.06~).33 1975-1977 Butter 38 0.18 a 0.10~).26 1976 Milk 77 0.35 0.1 -1.0 1976 Cheese 1630 4.04 b 1975 Cheese 1012 1.70 b 1976 Milk 46 0.71 1976 Milk 57 0.52 1976 Milk 77 0.44 1977 Milk 164 0.294 0.01-1.61 1975 Butter 182 0.246 0.01-1.32 1975 Cheese 99 0.326 0.01-1.90 1975 Milk 18 0.24 1974-1976 Butter 3 0.17 1974-1976 Cheese 6 0.19 1974-1976 Milk and butter 148 0.39 0.27~).54 1972-1974

Tuinstra et al. [3] Tuinstra et al. [3] Eikelenboom [4] Richou-Bac and Venant [5] Richou-Bac and Venant [5] Luquet et al. [6] Luquet et al. [6J Luquet et al. [6] Bliithgen et al. [7] Bliithgen et al. [7] Bliithgen et al. [-7] Siimmerman et al. [8] Siimmerman et al. 1-8] Siimmerman et al. [8] Claus and Acker [9]

a Median value b Highly polluted areas

m e a n , wh ich shows tha t the resul ts were even ly sp read .

S ign i f i can t d i f fe rences b e t w e e n a reas a n d seasons were

n o t es tabl i shed.

T h e P C B c o n t a m i n a t i o n o f m i l k a n d da i ry p r o d u c t s

can be exp la ined by the genera l ly p reva i l i ng e n v i r o n -

m e n t a l po l lu t i on , caus ing a c c u m u l a t i o n in fa t ty p ro -

ducts . T a k i n g in to acco.unt the i n t e r im F D A to l e r ance

o f 1.5 m g pe r kg o f fa t in mi lk and da i ry p r o d u c t s , the

c o n t e n t s r e c o r d e d c a n n o t be c o n s i d e r e d as ha rmfu l .

References

1. Jensen, S.: Report of a new chemical hazard. New Sci. 32, 612 (1966)

2. Greve, P.A., Grevenstuk, W.B.F.: Screening of Food-stuffs and human tissues for PCB's by the perchlorination method. Med. Fac. Landbouww. Rijksuniv. Gent. 42]2, 1795 (1977)

3. Tuinstra, L.G.M.Th., Spaas-Neuteboom, S.M., Roos, A.H.: The PCB content of milk and butter in the Netherlands. Neth. Milk Dairy J. 32, 187 (1978)

4. Eikelenboom, C.: Nachweis von polychlorierten Biphenylen in Milch. Z. Lebensm. Unters. Forsch. 163, 278 (1977)

5. Richou-Bac, L., Venant, A.: Recherche et dosage des diphenyles polychlor~s (PCB). Br6ves communications. 20e Congr~s Interna- tional de Laiterie. Paris 1978

6. Luquet, F.M., Mouillet, L., Mahieu, H. Boudier, J.F.: La conta- mination des laits par des r6sidus de PCB's. Lait. 173, 573-574 (1978)

7. Bliitghen, A., Heeschen, W., Tolle, A.: Tierexperimentelle Unter- suchungen zum Verhalten yon PCB's und HCB in der Nahrungs-~ kette Pflanze-Molchtier-Milch-Mensch. Bundesanstalt fiir Milch- forschung in Kiel, Jahresbericht B20, 1975

8. Si~mmerman, W., Rohleder, H., Korte, F.: Polychlorierte Bi- phenyle (PCB) in Lebensmineln. Z. Lebensm. Unters. Forsch. 166, 137 (1978)

9. Claus, B., Acker, L.: Zur Kontamination yon Milch und Milcher- zeugnissen mit chlorierten Kohlenwasserstoffen im westf~ilischen Raum. Z. Lebensm. Unters. Forsch. 159, 129 (1975)

Received January 14, 1980