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Avaliação das concentrações dos metais chumbo, manganês e cádmio em leite de vaca e Bebidas de soja existentes no mercado português
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O leite de vaca tem vindo a ser cada vez mais substituído pelas bebidas de soja na alimentação portuguesa. Esta substituição deve-se muito à intolerância à lactose, à crescente procura, principalmente pela população mais jovem, de produtos alimentares de origem não animal, menor valor calórico e menor teor de gordura e colesterol. Devido a isso, as bebidas de soja tornaram-se uma alternativa popular ao leite, contribuindo para a prevenção do aparecimento de doenças cardíacas, o cancro, a diabetes, a osteoporose e a obesidade. Contudo, as bebidas de soja e o leite de vaca apresentam características muito diferentes, pelo que só é possível tomar uma decisão consciente, tendo por base essas diferenças. O leite e os produtos lácteos, para além de serem constituídos por proteínas, lípidos, vitaminas e minerais, podem conter contaminantes químicos, que constituem um fator de risco para a saúde do consumidor, principalmente crianças, por consumirem mais leite em comparação com o seu peso, do que os adultos. No que diz respeito a contaminantes, a concentração de metais no leite pode ser influenciada por diversos fatores, como: o tipo de leite, as características do solo de que se alimenta a vaca (a alimentação da vaca interfere na composição do leite que esta produz), a composição mineral da água de irrigação, condições atmosféricas e etapas de processamento e armazenamento na produção do leite. Os metais são o grupo mais abundante de elementos na crosta terrestre. Alguns elementos são essenciais, como o manganês (Mn), o ferro (Fe) e o zinco (Zn), e outros são não essenciais, como o chumbo (Pb), o cádmio (Cd) e o arsénio (As), sendo tóxicos mesmo quando presentes em baixas concentrações. Os efeitos adversos causados na saúde pelos metais tóxicos dependem de diversos fatores, como a via de exposição (inalação, oral ou dérmica), do local de exposição, da duração da exposição e dos órgãos alvo. Por isso, a determinação de metais tóxicos é uma componente importante na segurança e qualidade dos produtos lácteos. O principal objetivo deste estudo foi determinar as concentrações de Pb, Cd e Mn em leites de vaca e bebidas de soja de diversas marcas adquiridas no mercado português. Os resultados obtidos para esses metais foram comparados entre si, com as ingestões diárias toleráveis estabelecidas/ recomendadas por agências reguladoras e com valores publicados em estudos semelhantes. O Pb e o Cd nas suas formas catiónicas e quando ligados a cadeias curtas de átomos de carbono podem levar ao desenvolvimento de doenças do sistema cardiovascular, rins, sistema nervoso, sangue e sistema esquelético. O Painel CONTAM da EFSA realizou uma avaliação de risco do chumbo e cádmio nos alimentos, estabelecendo um PTWI de 25 e 2.5 µg / kg de peso corporal, respetivamente. O Mn é um oligoelemento essencial que está presente em todas as células vivas e é essencial para o desenvolvimento normal. A Autoridade Europeia para a Segurança dos Alimentos (EFSA) propôs uma ingestão adequada de Mn, como 3 mg / dia para adultos. Concentrações mais elevadas de Mn podem tornar-se tóxicas, levando a danos neurodegenerativos progressivos que podem provocar sintomas semelhantes à doença de Parkinson. O Pb, Cd e Mn como estão presentes nos alimentos em baixas concentrações, na ordem das partes por bilião (ppb), a sua quantificação requer um método analítico preciso com uma sensibilidade adequada, tendo, por isso, sido usado a Espectrofotometria de Absorção Atómica em Forno de Grafite (GFAAS). Para demonstrar o grau de confiança dos resultados obtidos foi testada a linearidade, a gama de trabalho, os limites analíticos (limite de deteção e de quantificação), a precisão (repetibilidade e precisão intermediária), a exatidão e a recuperação pós-digestão, testes de validação indicados para este tipo de determinação. As estimativas das quantidades de Pb, Cd e Mn ingeridas pelo consumo das amostras de leite de vaca e bebida de soja analisadas tiveram em conta as recomendações das diretrizes dietéticas dos EUA. As diretrizes dietéticas dos EUA recomendam o equivalente a 720 ml de leite por dia para adultos e crianças/adolescentes dos 9 aos 17 anos. Para as crianças dos 4 aos 8 anos, recomendase uma ingestão diária de 600 ml de leite e dos 2 aos 3 anos de idade, o valor adequado é de 480 ml. Os resultados obtidos mostram que os leites de vaca têm uma concentração de Pb (média = 193 μg / L) superior à das bebidas de soja (média = 134 μg / L), apesar de não haver uma diferença significativa (p > 0.05). De acordo com a previsão de ingestão diária tolerável de Pb para adultos de 65 Kg e a estimativa da quantidade de Pb consumida por dia pelos adultos através da ingestão dos leites de vaca e das bebidas de soja analisados, observou-se em duas das amostras de leite de vaca analisadas e uma amostra de bebida de soja valores de Pb superiores à ingestão diária tolerável de 232.14 µg. Para o cádmio, a concentração de Cd nas bebidas de soja (média = 56 μg / L) é superior à encontrada nos leites de vaca (média = 25 μg / L), havendo uma diferença significativa (p < 0.05). De acordo com a previsão de ingestão diária tolerável de Cd para um adulto de 65 kg e a estimativa da quantidade de Cd consumida por dia pelos adultos através do consumo dos leites de vaca e bebidas de soja analisados, observa-se que três amostras de leite de vaca e doze amostras de bebida de soja têm valores de Cd superiores ao valor da ingestão diária tolerável de 21.43 µg. Em relação à quantificação do Mn, a concentração de Mn nas bebidas de soja (média = 1161 μg / L) é cerca de 20 vezes superior à encontrada nos leites de vaca (média = 58 μg / L), havendo uma diferença significativa (p < 0.05). Pela ingestão diária recomendada de Mn pela EFSA e a estimativa da quantidade de Mn consumida por dia pelas crianças e adultos que consomem os leites de soja e leites de vaca analisados, os resultados para as amostras de leite de vaca mostram valores inferiores à dose recomendada por dia para adultos e crianças/adolescentes dos 2 aos 17 anos. No entanto, nas amostras de bebidas de soja, as concentrações de Mn são superiores, principalmente para as crianças dos 2 aos 8 anos, sendo preocupante ao nível da sua formação, uma vez que o órgão mais sensível a elevadas concentrações de manganês é o cérebro. Para além da comparação com os valores de ingestão diária tolerável ou recomendada, fez-se uma comparação entre os resultados obtidos neste estudo e os valores de outros estudos semelhantes disponíveis na literatura. Foi observada uma discrepância entre os valores obtidos nos vários estudos, possivelmente, influenciada por fatores como, a diferente proveniência dos produtos analisados, o que implica grandes diferenças ambientais (temperatura, humidade, solo), práticas de cultivo e pastoreio diferentes e a estação do ano em que é obtida a amostra ser também diferente. A fim de evitar a contaminação ambiental com metais pesados, que é reconhecido como um perigo de saúde pública para todo o mundo, sugere-se uma monotorização dos metais pesados na água potável, uma vez que a água potável é uma das possíveis principais fontes de contaminação do leite. Neste estudo, os valores obtidos para a ingestão diária de Pb, Cd e Mn, através de amostras de leite de vaca e bebidas de soja foram calculados assumindo as exigências de consumo diário de leite proposto pelas diretrizes alimentares para os americanos. No entanto, o valor recomendado inclui outros produtos lácteos (como o iogurte e o queijo) e, por isso, os resultados obtidos são apenas aproximações, uma vez que outros produtos lácteos podem ter concentrações menores ou maiores desses metais. Além disso, considerou-se a ingestão diária recomendada de Mn por dia, pela EFSA, correspondente à concentração de Mn proveniente por todas as fontes deste metal e não apenas pelo leite. Para além de ter sido calculada uma ingestão diária tolerável de Pb e Cd para um adulto de 65 Kg, excluindo adultos com outro peso (a ingestão diária tolerável depende do peso corporal da criança/adulto). Assim, consumir uma quantidade de leite que exceda estes valores não implica necessariamente um risco aumentado para a saúde. Porém, este tipo de estudo é essencial para garantir a segurança dos alimentos, por permitir fazer uma estimativa da ingestão de metais através da alimentação.
Cow's milk has been increasingly replaced by soy drinks by Portuguese people. This substitution is largely due to lactose intolerance, the excessive consumption of products of animal origin and the lower caloric value, lower fat and cholesterol content of soy drinks Hence, soy drinks have become a popular alternative to milk, contributing to the prevention of heart disease, cancer, diabetes, osteoporosis and obesity. However, soy drinks and milk have very different characteristics, so it is only possible to make a conscious decision, based on these differences. Milk and dairy products, in addition to being made up of proteins, lipids, vitamins and minerals, can contain chemical contaminants, such as metals, may constituting a risk factor for consumer’s health, especially children as they consume more milk in comparison with their weight, than adults. The concentration of metals in milk can be influenced by several factors, such as: the type of milk, the characteristics of the soil from which it originated, the mineral composition of the irrigation water, atmospheric conditions and processing and storage steps in the production of milk. Metals are the most abundant group of elements in the earth's crust. Some elements are essential, such as manganese (Mn), iron (Fe) and zinc (Zn), and others are non-essential, such as lead (Pb), cadmium (Cd) and arsenic (As), being toxic even when present in low concentrations. The adverse health effects of toxic metals depend on a number of factors, such as the route of exposure (inhalation, oral or dermal), the exposure site, the duration of exposure, and the target organs. Therefore, the determination of toxic metals is an important component to the safety and quality of dairy products. The main objective of this study was to determine the concentrations of Pb, Cd and Mn in cow milks and soy beverages, from different brands in the Portuguese market. The results obtained were compared with each other, with the tolerable daily intake established/ recommended by regulatory agencies and with values published in similar studies. Pb and Cd in their cationic forms and when attached to short chains of carbon atoms can lead to the development of diseases of the cardiovascular system, kidneys, nervous system, blood and skeletal system. The EFSA CONTAM Panel carried out a risk assessment of Pb and Cd in food, establishing a PTWI of 25 and 2.5 μg/kg of body weight, respectively. Mn is an essential trace element that is present in all living cells and is essential for normal development. The European Food Safety Authority (EFSA) has proposed an appropriate intake of Mn of 3 mg per day for adults. Higher concentrations of Mn can become toxic, leading to progressive neurodegenerative damage that can cause symptoms similar to Parkinson's disease. Pb, Cd and Mn, as they are present in foods in low amounts, in the order of parts per billion (ppb), their quantification requires a precise analytical method with an adequate sensitivity, having therefore been used in Graphite Furnace Atomic Absorption Spectrophotometry (GFAAS). To guarantee the reliability of analytical data, a validation method was carried out that includes linearity, the working range, analytical limits (limit of detection and quantification), precision (repeatability and intermediate precision), accuracy, specificity / selectivity and post-digestion recovery. Those loaded with the amounts of Pb, Cd and Mn ingested by consuming the analyzed amounts of cow's milk and soy drink took into account the recommendations of the US dietary guidelines. US dietary guidelines recommend the equivalent of 720 ml of milk per day for adults and children / adolescents aged 9 to 17. For children aged 4 to 8 years, a daily intake of 600 ml of milk is recommended and from 2 to 3 years of age, the appropriate amount is 480 ml. The results found show that cow's milk has a Pb concentration (mean = 193 μg / L) higher than soy drinks (average = 134 μg / L), although there is no significant difference (p > 0.05). According to tolerable daily intake of Pb for adults of 65 kg and the estimate of the amount of Pb consumed per day by adults through the intake of cow's milk and the expected by soy drinks, it was observed in two of the cow milk of analyzed cow and a sample of soy drink with an equal value, all of these Pb values being higher than the tolerable daily intake of 232.14 µg. Concentration of Cd in soy drinks (mean = 56 μg / L) is significantly higher (p < 0.05) than that found in cow's milk (average = 25 μg / L). According to the tolerable daily intake of Cd for an adult of 65 kg and the estimate of the amount of Cd consumed per day by adults, through the consumption of cow's milk and soy drinks, it is observed that three of milk from cow's milk and twelve soy drink drinks have Cd values higher than the tolerable daily intake value of 21.43 µg. Regarding the quantification of Mn, the concentration of this metal in soy drinks (mean = 1161 μg / L) is about 20 times higher than that found in cow's milk (mean = 58 μg / L), with significant difference (p < 0.05). A cording to EFSA's recommended daily intake of Mn and the estimated amount of Mn consumed per day by children and adults who consume the estimated soymilk and cow's milk, the results for calculating cow's milk values below the recommended dose per day for adults and children / teenagers from 2 to 17 years old. However, in the administrations of soy drinks, as they are from Mn, they are superior, mainly for children from 2 to 8 years old, being of concern in terms of their formation, since the organ most sensitive to high manganese is the brain. A comparison was also made between the results obtained in this study and the values of other similar studies available in the literature. A discrepancy was observed between the values chosen in the various studies, possibly influenced by factors such as the different origin of the products, which may implies large differences (temperature, humidity, soil), different cultivation and grazing practices and the season of the year. In order to avoid environmental contamination with heavy metals, which is recognized as a public health hazard for the whole world, they must be monitored, mainly in terms of drinking water, since drinking water is one of the main possible sources of contamination in cow milk and soy beverages.
Cow's milk has been increasingly replaced by soy drinks by Portuguese people. This substitution is largely due to lactose intolerance, the excessive consumption of products of animal origin and the lower caloric value, lower fat and cholesterol content of soy drinks Hence, soy drinks have become a popular alternative to milk, contributing to the prevention of heart disease, cancer, diabetes, osteoporosis and obesity. However, soy drinks and milk have very different characteristics, so it is only possible to make a conscious decision, based on these differences. Milk and dairy products, in addition to being made up of proteins, lipids, vitamins and minerals, can contain chemical contaminants, such as metals, may constituting a risk factor for consumer’s health, especially children as they consume more milk in comparison with their weight, than adults. The concentration of metals in milk can be influenced by several factors, such as: the type of milk, the characteristics of the soil from which it originated, the mineral composition of the irrigation water, atmospheric conditions and processing and storage steps in the production of milk. Metals are the most abundant group of elements in the earth's crust. Some elements are essential, such as manganese (Mn), iron (Fe) and zinc (Zn), and others are non-essential, such as lead (Pb), cadmium (Cd) and arsenic (As), being toxic even when present in low concentrations. The adverse health effects of toxic metals depend on a number of factors, such as the route of exposure (inhalation, oral or dermal), the exposure site, the duration of exposure, and the target organs. Therefore, the determination of toxic metals is an important component to the safety and quality of dairy products. The main objective of this study was to determine the concentrations of Pb, Cd and Mn in cow milks and soy beverages, from different brands in the Portuguese market. The results obtained were compared with each other, with the tolerable daily intake established/ recommended by regulatory agencies and with values published in similar studies. Pb and Cd in their cationic forms and when attached to short chains of carbon atoms can lead to the development of diseases of the cardiovascular system, kidneys, nervous system, blood and skeletal system. The EFSA CONTAM Panel carried out a risk assessment of Pb and Cd in food, establishing a PTWI of 25 and 2.5 μg/kg of body weight, respectively. Mn is an essential trace element that is present in all living cells and is essential for normal development. The European Food Safety Authority (EFSA) has proposed an appropriate intake of Mn of 3 mg per day for adults. Higher concentrations of Mn can become toxic, leading to progressive neurodegenerative damage that can cause symptoms similar to Parkinson's disease. Pb, Cd and Mn, as they are present in foods in low amounts, in the order of parts per billion (ppb), their quantification requires a precise analytical method with an adequate sensitivity, having therefore been used in Graphite Furnace Atomic Absorption Spectrophotometry (GFAAS). To guarantee the reliability of analytical data, a validation method was carried out that includes linearity, the working range, analytical limits (limit of detection and quantification), precision (repeatability and intermediate precision), accuracy, specificity / selectivity and post-digestion recovery. Those loaded with the amounts of Pb, Cd and Mn ingested by consuming the analyzed amounts of cow's milk and soy drink took into account the recommendations of the US dietary guidelines. US dietary guidelines recommend the equivalent of 720 ml of milk per day for adults and children / adolescents aged 9 to 17. For children aged 4 to 8 years, a daily intake of 600 ml of milk is recommended and from 2 to 3 years of age, the appropriate amount is 480 ml. The results found show that cow's milk has a Pb concentration (mean = 193 μg / L) higher than soy drinks (average = 134 μg / L), although there is no significant difference (p > 0.05). According to tolerable daily intake of Pb for adults of 65 kg and the estimate of the amount of Pb consumed per day by adults through the intake of cow's milk and the expected by soy drinks, it was observed in two of the cow milk of analyzed cow and a sample of soy drink with an equal value, all of these Pb values being higher than the tolerable daily intake of 232.14 µg. Concentration of Cd in soy drinks (mean = 56 μg / L) is significantly higher (p < 0.05) than that found in cow's milk (average = 25 μg / L). According to the tolerable daily intake of Cd for an adult of 65 kg and the estimate of the amount of Cd consumed per day by adults, through the consumption of cow's milk and soy drinks, it is observed that three of milk from cow's milk and twelve soy drink drinks have Cd values higher than the tolerable daily intake value of 21.43 µg. Regarding the quantification of Mn, the concentration of this metal in soy drinks (mean = 1161 μg / L) is about 20 times higher than that found in cow's milk (mean = 58 μg / L), with significant difference (p < 0.05). A cording to EFSA's recommended daily intake of Mn and the estimated amount of Mn consumed per day by children and adults who consume the estimated soymilk and cow's milk, the results for calculating cow's milk values below the recommended dose per day for adults and children / teenagers from 2 to 17 years old. However, in the administrations of soy drinks, as they are from Mn, they are superior, mainly for children from 2 to 8 years old, being of concern in terms of their formation, since the organ most sensitive to high manganese is the brain. A comparison was also made between the results obtained in this study and the values of other similar studies available in the literature. A discrepancy was observed between the values chosen in the various studies, possibly influenced by factors such as the different origin of the products, which may implies large differences (temperature, humidity, soil), different cultivation and grazing practices and the season of the year. In order to avoid environmental contamination with heavy metals, which is recognized as a public health hazard for the whole world, they must be monitored, mainly in terms of drinking water, since drinking water is one of the main possible sources of contamination in cow milk and soy beverages.
Descrição
Tese de mestrado, Biologia Humana e Ambiente, Universidade de Lisboa, Faculdade de Ciências, 2021
Palavras-chave
leite de vaca bebidas de soja metais Espectrometria de Absorção Atómica Teses de mestrado - 2020