Pesquisas confirmam de contaminação química e hormonal do leite nos EUA e Europa
[Por Henrique Cortez, do EcoDebate] Recentemente ocorreu um grande escândalo mundial em relação ao leite produzido na China, contaminado com melamina, um produto que provocou a morte de seis crianças e afetou outras 300.000 no ano passado.
No entanto, duas novas pesquisas, publicadas na edição online da revista Journal of Chromatography B, indicam que o leite nos EUA e Europa pode estar contaminado com estrogênios e com fármacos de uso veterinário.
A pesquisa “Quantitative measurement of endogenous estrogen metabolites, risk-factors for development of breast cancer, in commercial milk products by LC–MS/MS”, realizada nos EUA, faz parte de um grande esforço internacional de rastreamento de estrogênios ambientais. Os estrogênios ambientais ou xenoestrogênios ou estrogênios ambientais vem sendo, crescentemente, identificados como fatores de risco para o desenvolvimento de câncer de mama.
A pesquisa identificou a presença abundante de estrona (E1) e estradiol (E2) em diversos tipos de leite. Alguns dos estrogênios identificados, tal como o 2-hydroxyestrone, podem ser perigosos em dosagens elevadas.
A segunda pesquisa, “Comprehensive fast multiresidue screening of 150 veterinary drugs in milk by ultra performance liquid chromatography coupled to time of flight mass spectrometry”, realizada na Europa, comprovou a presença de 150 drogas veterinárias no leite, mesmo diante das severas regras européias.
Este artigo reafirma a argumentação de Ana Echevenguá no artigo “Antibióticos, o mal que entra pela boca do homem” e de nossa matéria ‘Antibióticos usados em animais são absorvidos pelas hortaliças cultivadas em solo adubado com resíduos animais’.
Mais uma vez reafirmamos que a situação real no Brasil não deve ser muito diferente, salvo no fato de que o risco de contaminação de alimentos é um tema “tabu”, pouco ou nada pesquisado e nada fiscalizado, mesmo sendo um dos mais importantes componentes da segurança alimentar.
Os artigos apenas estão disponíveis para acesso aos assinantes da revista Journal of Chromatography B. Para maiores informações, abaixo, transcrevemos os abstracts:
Quantitative measurement of endogenous estrogen metabolites, risk-factors for development of breast cancer, in commercial milk products by LC–MS/MSstar
doi:10.1016/j.jchromb.2009.01.032
Daniel W. Farlownext terma, Xia Xua and Timothy D. Veenstra
Laboratory of Proteomics and Analytical Technologies, Advanced Technology Program, SAIC-Frederick, Inc., NCI-Frederick, Frederick, MD 21702, United States
Received 15 December 2008; accepted 23 January 2009. Available online 31 January 2009.
Abstract
Increased levels of estrogen metabolites (EM) are associated with cancers of the reproductive system. One potential dietary source of EM is milk. In this study, the absolute quantities of unconjugated (free) and unconjugated plus conjugated (total) EM were measured in a variety of commercial milks (whole, 2%, skim, and buttermilk). The results show that the milk products tested contain considerable levels of EM; however, the levels of unconjugated EM in skim milk were substantially lower than that observed in whole milk, 2% milk, and buttermilk. Whole milk contained the lowest overall levels of EM while buttermilk contained the highest. As anticipated, soy milk did not contain the mammalian EM measured using this method. The relatively high levels of catechol estrogens detected in milk products support the theory that milk consumption is a source of EM and their ingestion may have a dietary influence on cancer risk.
Keywords: Estrogen metabolites; Milk; Breast cancer; Biomarkers; Selected reaction monitoring mass spectrometry
Article Outline
1. Introduction
2. Experimental
2.1. Reagents and materials
2.2. Milk samples
2.3. Preparation of stock and working standard solutions
2.4. Calibration standards
2.5. Sample preparation procedure
2.6. Capillary liquid chromatography–tandem mass spectrometry analysis (LC–MS/MS)
2.7. Quantitation of estrogen metabolites (EM)
3. Results and discussion
3.1. Overall levels of estrogen metabolites in milk products
3.2. Levels of specific estrogen metabolites in milk products
Acknowledgements
Appendix A. Supplementary data
References
This paper is part of the special issue “Quantitative Analysis of Biomarkers by LC–MS/MS”, J. Cummings, R.D. Unwin and T. Veenstra (Guest Editors).
Corresponding Author Contact Information Corresponding author. Tel.: +1 301 846 7286; fax: +1 301 846 6037.
Comprehensive fast multiresidue screening of 150 veterinary drugs in milk by ultra performance liquid chromatography coupled to time of flight mass spectrometry
doi:10.1016/j.jchromb.2009.03.006
Didier Ortelli, Emmanuelle Cognarda, Philippe Jana and Patrick Eddera
aFood authority control of Geneva, Quai Ernest-Ansermet 22, CP 76, CH-1211 Geneva 4, Switzerland
Received 15 August 2008; revised 3 March 2009; accepted 5 March 2009. Available online 11 March 2009.
Abstract
This paper shows the use of ultra-performance liquid chromatography (UPLC) coupled to orthogonal acceleration time of flight mass spectrometry (TOF MS) for the comprehensive screening of 150 veterinary drugs residues in raw milk. An easy sample preparation based on protein precipitation associated with ultrafiltration was hyphenated to fast chromatography. This method enabled the screening for more than 50 samples per day and searched for 150 drugs and metabolites included avermectines, benzimidazoles, beta-agonists, beta-lactams, corticoides, macrolides, nitroimidazoles, quinolones, sulfonamides, tetracyclines and some others. Identification of contaminants is based on accurate mass measurement. UPLC-TOF also showed very good performances for quantitation and allowed the determination of majority of compounds below MRL. An in-house validation procedure was conducted based on European directive 2002/657/EC with measurement of response function, accuracy, repeatability, limits of detection (LOD), decision limit (CC?) and detection capability (CC?).
Keywords: Milk; Veterinary drugs; Fast liquid chromatography; UPLC; Time of flight; TOF; Mass spectrometry
Corresponding Author Contact InformationCorresponding author. Tel.: +41 22 327 39 00; fax: +41 22 327 39 89.
[EcoDebate, 17/03/2009]
Inclusão na lista de distribuição do Boletim Diário do Portal EcoDebate
Caso queira ser incluído(a) na lista de distribuição de nosso boletim diário, basta que envie um e-mail para newsletter_ecodebate-subscribe@googlegroups.com . O seu e-mail será incluído e você receberá uma mensagem solicitando que confirme a inscrição.