Thesis Of Mr Minh - Đi In (1).Docx

1 INTRODUCTION According to the Department of Food Safety and Hygiene data in December 2017, there are 1,235 enterprises operating in manufacturing and trading children''''s products in Vietnam Among the[.]

According to the Department of Food Safety and Hygiene data inDecember 2017, there are 1,235 enterprises operating in manufacturing andtrading children's products in Vietnam Among them, over 50% of businessessell functional food products for children The rest of the enterprises trademainly supplement products and breast milk substitutes (mainly nutritionaland formula products) Hai Phong is a large city in the North of Viet Nam,where many factories produce milk and dairy products Moreover, theconsumption of milk and dairy products in Hai Phong is relatively high

In recent years, the number of food poisoning cases has beenincreasing, posing an alarming food quality problem in hygiene and safety.Therefore, food safety is an important issue for people in all countries.However, in the last few decades, food safety has been concerned then controlpractices have increased In order to ensure food safety and hygiene,management and monitoring activities need to be done synchronously on boththe business side and the State management agencies [1]

Product safety, including nutrition for children, especially milk anddairy products, is one of the most important food production and supply chainelements If we do not pay adequate attention to the safety of food products,they can negatively affect children's health, and make economic losses to themanufacturers It can be estimated that unsafe food accidents cost industry,government, and society about 20 billion dollars a year Many businesses areunable to recover from a foodborne illness outbreak and have to close theirbusinesses permanently [2]

Milk and dairy products are sensitive, "high-risk" foods due to theirhigh protein nutrient profile and high risk of contamination with

microorganisms from the environment as well as toxic chemicals from rawmaterials and through processing In the past, there were several significantfood poisoning incidents in the dairy industry Cheddar Cheese contaminated

Salmonella sp caused about 28,000 to 30,000 cases in Colorado (1976).

Pasteurized milk contaminated with Yersinia enterocolitica caused illness in

thousands of people in Arkansas (1982) In California, a Mexican soft cheese

contaminated with Listeria monocytogenes related to approximately 100

infections and 39 deaths (1985) In Chicago, about 20,000 people are infected

by Salmonella sp presenting in pasteurized milk (1985) [3] Recently, a case

of collective poisoning due to enterotoxin infection from Staphylococcus

aureus in pasteurized milk has made over 14,700 people sick.

The inspection and supervision activities of the quality of importedchildren's nutritional products and domestically produced products remaindifficult In particular, the quality control of domestically produced children'snutrition products has not been carried out yet

Because of the above reasons, we have conducted research titled

"Research on the current situation of some chemical agents in milk and dairy products for children in Hai Phong, 2020" with the following aim:

To describe the current contamination of some chemical agents in milk and dairy products for children under 36 months old in Hai Phong, 2020.

Chapter 1 LITERATURE REVIEW

1.1 Overview of food safety

1.1.1 Some terms used in research

According to the national standard TCVN 11216: 2015 issued onDecember 31st, 2015, compiled by the National Standard TechnicalCommittee TCVN/TC/F12 for Milk and Milk Products, the GeneralDepartment of Standards, Metrology and Quality Science and Technologypublishes definitions related to milk and dairy products as follows [1]:

- Milk: Nutrients obtained from one or more milk from the mammaryglands of dairy animals

- Raw milk: Milk without the addition or removal of milk components,unpasteurized at temperatures higher than 40°C or other equivalent methods,used for consumption in liquid milk, or further processing

- Liquid fresh milk products:

+ Pasteurized/sterilized fresh whole milk: The product is whollyprocessed from raw, fresh milk, without any addition of milk or anyingredients, including a food additive, that has been processed by apasteurization/sterilization method

+ Pasteurized / sterilized fresh milk: The product is made from rawfresh milk, with added sugar and other ingredients such as juice, cocoa,coffee, food additives, processed by pasteurization / sterilization

- Powdered milk: A powdered product obtained by removing waterfrom raw milk The fat and/or protein content of milk or cream can beadjusted by adding and/or removing the milk component without changingthe whey protein to the milk’s casein ratio

- Milkfat: Fatty products obtained entirely from milk and/or dairyproducts by removing most of the water and non-fat solids, with a milkfatcontent not less than 99.6% mass, has a melting point of about 37°C.

- Products in the form of Cheese: Products in the form of very hard,hard, semi-hard, or soft, have been cooked or not through the ripening stage,may have shells in which the ratio of whey protein/casein does not exceedexcess in milk, obtained from the coagulation of milk proteins and/or dairyproducts

- Fermented milk: Products obtained by fermentation of milk can beprepared from milk products with or without changing the prescribedcomposition by using suitable microorganisms for reducing pH with orwithout coagulation (isoelectric precipitation)

1.1.2. Overview of food pollution and poisoning in children

1.1.2.1 Overview of food pollution and poisoning

Food pollution has been an issue for thousands of years; however,developments in agribusiness and globalization have spread this across theplanet [3]

According to a WHO (2020) review, unsafe food containing harmfulbacteria, viruses, parasites, or chemical substances, causes more than 200diseases – from diarrhea to cancers It is estimated that about 600 million fallill after eating contaminated food, and 420,000 die every year, resulting in theloss of 33 million healthy life years (DALYs) Diarrheal diseases are the mostcommon illnesses resulting from contaminated food consumption, causing

550 million people to fall ill and 230,000 deaths every year [4]

America Center For Disease Control And Prevention (CDC) reported 19

056 infections, 4.200 hospitalizations, and 80 deaths related to Foodbornedisease in 2013 In that detail, a person aged ≥65 years with Cyclospora,Listeria, and Vibrio, and children aged <5 years with all the other pathogensaccounted for the highest proportion.[5]

European Center for Disease Prevention and Control (ECDC) reported5.251 wave outbreaks of foodborne disease, including water-borne outbreaks,

in 32 nations of the EU in 2014 Overall, 45.665 cases, 6.438 hospitalizations,and 27 deaths were reported Viruses became the most common reason forfoodborne disease with the highest number of cases (20.4% of all), andSalmonella (20.0% of all) were the second reason [6]

In 2019, Zemichael Gizaw performed a systematic literature reviewabout Public health risks related to food safety issues in the food market,based on 81 full-text articles The analysis of 81 articles resulted in sevencommon public health risks related to food safety in the food market.Microbial contamination of foods, chemical contamination of foods, foodadulteration, misuse of food additives, mislabeling, genetically modifiedfoods (GM foods), and outdated foods or foods past their use-by dates wereidentified food safety–related public health risks in the food market In thisreview, 21 articles reported pathogenic microorganisms in different fooditems in the food market 15 articles reported that contamination of foods withhazardous chemicals is a major public health Chemical contamination offood causes millions of poisoning cases with thousands of hospitalizationsand deaths each year [7]

In low and middle-income countries, there was some evidence thatfood-related illness can cause 18 million years of disease-adjusted survivalburden every year, at least for parasites in food and aflatoxin that takes 1–2million years [8]

From 2011 to 2016, seven foodborne diseases were found in Vietnam with 4.012,038 cases, of which 123 cases died [9] According to surveysconducted in Hanoi and Ho Chi Minh City, about 10% of vegetable samplesexceeds the national standard for pesticide residue levels, and 2 to 3% showusing prohibited pesticide products [10] In Hue, a research group has

-surveyed 1.035 samples examined: 543 food samples of all kinds and 492hands - utensils samples Based on the permitted biological pollution limitaccording to the Decision No 46/2001 of Health Department, they found out11.1% samples (n = 63) failed about mold, 11.1% samples (n = 99) failedabout aerobic bacteria indicator, 19.9% samples (n = 543) failed coliformsindicator, and 24.8% samples (n = 444) failed E coli indicator; 21.7% of handand utensils samples were contaminated with E coli In this detail, 9.1% (n =99) samples failed 2 indicator and 2.1% (n = 99) samples failed threeindicators of the Decision [11]

Food security, food safety, and healthy nutrition are critical aspects offood systems with important implications for population health, especiallyaffecting infants, the young, the elderly, and the sick

1.1.2.2 Overview of food pollutants and children’s health

Infants and young children, pregnant women, the elderly, and peoplewith weak immune systems are particularly at risk of getting and dying fromfood-related illnesses Malnourished infants and children are especiallyexposed to food hazards and are at a higher risk of developing serious forms

of the disease Therefore, the effects of food pollutants on children’s healthhave received much attention from the community

In 2008, a scandal involving high levels of melamine was discovered inbaby formula and other liquid and powdered milk products made in China.High melamine levels in infant milk and other dairy products have resulted insevere health effects and illnesses in Chinese infants and young children [12]

According to WHO, children under five years of age carry 40% of the

foodborne disease burden, with 125 000 deaths every year [4] Diarrheacauses more than half of the global burden of food-borne illnesses, causing

550 million people to fall ill and 230.000 die each year Children are

particularly at risk of food-borne diarrheal diseases, with 220 million gettingsick and 96.000 dying each year Diarrhea is often caused by eating meat,eggs, raw or undercooked produce contaminated with norovirus,Campylobacter, non-typhoid Salmonella, and pathogenic E coli [13].

About 60 million children under five years of age become sick, and50.000 people die from foodborne illnesses in Southeast Asia each year Inthe Americas, 31 million children under five fall ill every year fromcontaminated food, and it results in more than 2000 of these children dying ayear As in other regions, the Atlantic has the highest burden among childrenunder five years old, with 40 million sick people and 7.000 deaths a year It isestimated that more than 100 million people living in the EasternMediterranean get sick from food every year, and 32 million of those arechildren under 5 [13]

Recently, a trial of 168 baby foods from major US manufacturers foundthat 95% contained lead, 73% contained arsenic, 75% contained cadmium,and mercury 32%, 1/4 of all foods contain all four heavy metals [14] FDAdata show that nearly half (47%) of infant rice cereals sampled from retailstores in 2014 had inorganic arsenic content (≥ 100 ppb) [15]

In Spain, Aflatoxin was detected in 12 samples (20%), six of whichexceeded the EU maximum level for aflatoxin B1 set at 0.10 µg/kg [16].Also, in Spain, 91 baby food samples were analyzed for aflatoxin and found

66 positives (72.5%), of which 7 samples (7.7%) exceeded 0.10 µg/kg foraflatoxin B1 [17] Consequently, the presence of aflatoxin is relativelyfrequent in infant cereals, albeit in general, at low levels

In France, a general dietary study estimated the diet’s chronic exposure

to pesticide residues and health risks for infants and under 3-year-oldchildren Generally, they analyzed 516 pesticides and metabolites in 309

synthetic food samples, including 219 processed baby foods and 90 commonfoods, which includes 97 percent for infants and young children Thesesynthetic samples were collected from 5.484 food products purchased in allseasons from 2011 to 2012 and processed for consumption Pesticide residueswere detected in 67% of samples and quantified in 27% of baby food samplesand 60% of conventional food samples 78 different insecticides wereidentified, and 37 of these were quantified at levels from 0.02 to 594 µg/kg[18].

In the Czech Republic, during the three years of the monitoringprogram, 522 samples of fresh apples, six brands of whole fruits and variousfruits prepared from these ingredients were analyzed Pesticide residues weredetected in 59.5% of fresh apple samples However, 1.4% of the samplesexceeded the European Union’s maximum residue levels (MRLs) Fruit food

is the item with the lowest detected residue rate in only 16% of the samples.Nine percent of these products exceed 0.01mg/kg In 25% of fresh apples and10% of whole fruit, two types of residues were detected simultaneously Theorganic phosphate insecticides and fungicides representing phtalimides,sulphamides, and dicarboximides are the most commonly found residues [19]

Researchers in Korea collected 239 food samples from 46 childrenparticipating in a study evaluating pesticide exposure in children The studyshowed that 14% of those food samples, respectively, contained at least oneorganic phosphate, and 5% of them contained at least one pyrethroidpesticide They measured a total of 11 OP insecticides, at levels 1 to 387 ng/g,and three pyrethroid pesticides, at levels from 2 to 1,133 ng/g, in our foodsamples children The authors also found that many of the foods consumed bychildren were also on the list of the most contaminated food items reported bythe Environment Working Group [20]

The first months of life are a crucial time in the developmental process

of humans, and the quality of the formula is vital for the nervous,reproductive, digestive, respiratory, and immune systems The presence ofcontaminant residues in baby foods can pose a risk to children's healthbecause organs such as the brain, reproductive and immune systems can beeasily affected by these harmful ingredients, especially in children under 4months (16 weeks) old Infants are more sensitive to the effects of foreignchemicals than adults, a smaller dose of this substance may be sufficient tocause adverse effects in the infant when compared with the dose required toinduce adverse effects in adults In addition, infants have a higherconsumption of food related to body weight than other age groups, whichexposes them to more exposure to possible contaminants and residues in foodfor this particular population group

1.2 Current situation of contamination of milk and dairy products for children under 36 months

Chemical contaminants in milk and dairy products include substancesthat can contaminate these foods during production, processing, or packaging.Veterinary drugs, heavy metals, mycotoxins, and plant protection chemicals,additives are chemical contaminants that can get into the feed, and they canform a residue in milk and dairy products [21] Today, improved analyticalmethods that detect extremely low chemical concentrations have shown thatmilk and dairy products can be contaminated with a range of potentiallyharmful chemicals, some of which were mentioned above [22]

1.2.1 Heavy metal contamination in milk and dairy products for children under 36 months

The results of rapid urbanization and industrial development havecaused environmental pollution around the world Furthermore, heavy metalpollution is threatening human health through the food chain

In the study of Ahmet Ayar (2009), the average Cd content of raw milksamples was 0.017 mg/kg Cd concentrations in butter (0.015 mg/kg), wheypowder (0.009 mg/kg) and yogurt samples (0.009 mg/kg) were lower thanconcentrations in milk samples The lowest mean concentrations weredetermined in milk powder and yogurt samples This indicated that Cd wascontaminated to whey at a lower rate [23].

In recent years, the content of toxic heavy metals in milk exceedingstandard limits has been reported in several countries, including Poland(Pilarchot et al 2013), Iran (Rahimi et al 2013), Egypt (Malhat et al 2012),and Nigeria (Ogabiela et al 2011) [24], [25], [26], [27]

Rahimi (2013) described that the average Pb and Cd concentraions incow, buffalo, goat, and sheep milk samples were 9.88 ± 4.75 and 6.16 ± 3.16,7.37 ± 3, respectively 18 and 12.1 ± 5.63 and 0.92 ± 0.77; 0.74 ± 0.41, 2.33 ±1.23 and 3.31 ± 1.53 ng/ml, [24] respectively

In the review of Amir Ismail (2019), mean Pb and Cd levels in milksamples from different countries were found in the range of 0.002–3.152mcg/ml and 0.002–0.250 mcg/ml The author found that milk samples fromsome developing countries such as Egypt, Serbia, Poland, Pakistan, andPhilippines showed 100% pollution with Pb, Cd exceeding the standard limit.Moreover, Ismail found the concentration of As detected in various studiesfrom different countries varied from 0.002 to 0.044 mcg/ml In which thehighest amount of As was milk samples from Bangladesh and Pakistan [28]

In the study of Pouya Parsaei (2019), the average Cd, Pb and Hgcontent obtained from 1100 samples was 3.62 ± 0.35 ppb (range: 0.06-14.03ppb), 11,73 ± 1.09 ppb (range: 0.12-33.62 ppb) and 4.35 ± 0.42 ppb (range:1.03-10.38 ppb), respectively The highest concentration of Cd, Pb, and Hgwas found in raw cow samples (4.05 ± 0.38, 12.36 ± 1.21, and 5.76 ± 0.53ppb), while raw camel milk contains the lowest concentrations of heavy

metals The average concentrations of heavy metals Cd and Hg are lower thanthe limits allowed by published standards, while Pb limits are higher [29].

It seems that in developing countries, rapid urbanization andindustrialization, fewer stringent regulations, and improper enforcement due

to ineffective law enforcement have resulted in the increase of heavy metals

in milk In contrast, in developed countries, there are fewer problems withheavy metal pollution [28]

1.2.2 Contamination of mycotoxins and melamine in milk and dairy products for children under 36 months

Milk is a good source of nutrients, providing many essential substancesfor the body, including proteins, fats, carbohydrates, vitamins, and essentialminerals However, the content of these substances in milk can becounterfeited Some examples of artificial milk ingredients include watersupplements, whey, vegetable oils, proteins, other sourced milk, et cetera

Mycotoxin is a secondary metabolite produced by mycelium thatcauses a toxic reaction when ingested by humans and animals Fusarium,Aspergillus, and Penicillium are the most damaging molds that producemycotoxins and contaminate human food and feed before and during aharvest or improper storage

The presence of AFM1 in animal milk has been reported in numerousstudies worldwide In the review study of Myra Evelyn Flores-Flores (2015),22,189 milk samples were analyzed for determining AFM1 level; at least9.8% of them (2190 samples) exceeded the limits set by the EU (0.05 mcg /kg) This rate may be higher because many studies only report samplesexceeding the US requirement for AFM1 (0.5 mcg/kg), higher than theEuropean regulation [33] Also, according to this study, regarding the number

of continental samples exceeding the limit set by the EU, at least 1709 werefrom Asia (7.7% of total samples and 26.8% of Asian samples), 253 from

Africa (1.1% of total samples and 25.8% of African samples), 119 fromEurope (0.5% of total samples, and 0.9% of European samples) and 109 fromAmerica (0.5 % of total samples and 8.6% of US samples) It can be seen thatAsia has the highest proportion of excess milk samples, even though totalAsian samples represent only 28.7% of all samples tested worldwide [33].

In a study about AFM1 in cow milk (2016), data were collected fromstudies performed in recent years; the results showed that the incidence ofAFM1 in milk samples and dairy products is relatively lower in Europeancountries (Portugal, Turkey, Italy, and Croatia), regardless of the sample type

In contrast, studies in Asian countries such as China, Thailand, and Taiwanshowed the prevalence of toxins in 100% samples [34]

The proportion of fumonisin in milk samples has not been extensivelystudied However, it should be noted that in all of the following cases, thequantitative limits of the methods used are considered high (1 to 50 g/kg).Gazzotti et al (2009) developed a method for the determination andquantification of AFB1 in liquid chromatography samples - massspectrometry; Out of 10 samples were analyzed, 8 contaminated with thismaterial exceeded the quantitative limit (0.26 μg/kg) [34] AlthoughZearalenone (ZEN) is not one of the mycotoxins present high in milk and itsderivatives, several studies have reported ZEN contamination In a study inItaly, Meucci et al (2011) detected ZEN at 9% (maximum 0.76 mcg/L), α-ZEN in 26% (maximum 12.91 g/L), and β- ZEN in 28% (maximum 730.24μg/L) of infant formula samples which were studied [34]

In mycotoxin, AFM1 is the most commonly found, as well as the twomycotoxins listed above; there are many other mycotoxins that cancontaminate milk and dairy products

Melamine is a substance added to milk to increase milk’s proteincontent at a low cost; the protein content of milk is determined based on theamount of nitrogen in milk by Kjeldahl and Duma’s method.

In a scandal involving high levels of melamine in China, melamine waspresent in 87 out of the Sanlu brand’s 111 formula samples The averagemelamine concentration was 1212 mg/kg, and melamine concentrations inindividual samples ranged from <0.05 to 4700 mg/kg The average melamineconcentration in 38 samples of Sanlu non-branded powdered milk analyzedfrom Gansu Province was 4.06 mg/kg [12] Following the first report onmelamine in baby formula products in China, the international food regulatorconfirmed that other foods containing milk, such as milk and whey powder,casein, and candies were derived from milk, powdered coffee products,biscuits, chocolates, dairy drinks, and cakes can be contaminated withmelamine [12]

In general, the following data has been published by the InternationalNetwork of Food Safety Agencies (INFOSAN) on the melamine content ofmilk and dairy products Biscuits, cakes and confectionery samples (0.6-945.86 mg/kg); liquid milk and yogurt products (0.5-648 mg/kg); frozendesserts (39-60.8 mg/kg); powdered milk and cereal products (0.3-1,143mg/kg); processed food (0.6-41 mg/kg); ingredient food processing (1.5-6,694mg/kg); and animal feed (116.2-410 mg/kg) [30]

Deabes and El-Habib (2012) evaluated melamine content in 22samples, including infant formula, growth formula, and whole milk powder.Melamine was found in 100% of the analyzed samples, and the highestmelamine content of 258 mg/kg was found in infant formula [31] Meanwhile,

in Turkey, Melamine was not found in infant formulas and pasteurized milk,while 2% of cheese, 8% of powdered milk, and 44% of yogurt samplescontained melamine in levels 121.694 ± 146 and 294 ± 98 μg/kg These

findings are below the limits set by the Codex Alimentarius Commission andthe European Union [32].

Research by Maryam Jalili (2017) showed that: 100% of milk samplesfrom India, Iran, and the USA analyzed are positive for melamine However,the melamine concentration was within the allowable limits [30] Contrary tothese reports, in Australia, 360 dairy food samples were tested for thepresence of melamine No melamine was detected in any of these samples;the reporting limit (LOR) varies from <0.1 to <1.0 mg/kg, depending on thetype of food and the method of analysis used [12]

It can be said that melamine exists in most studies at different levelsbecause it can contaminate food in many different ways

1.2.3 Contamination of veterinary drugs in milk and dairy products for children under 36 months

Each year, 63.151 ± 1.560 tons of antibiotics are being used inlivestock worldwide Global antimicrobial use in animals could nearly double

by the 2030s [35]

Sabbya Sachi (2019), in a review study, found that: Between 2000 and

2017, 188 studies found antibiotic residues in milk Relevant publicationsfrom 2000 to 2009 were 81 (36.16%) in volume, more than double thenumber four decades earlier, for a total of 36 (16.07%) During this decade,47.77% of studies (107 studies) varied over the past 57 years, which clearlyidentified a growing trend with concern about antibiotics in milk andantibiotic detection in milk [36] Similarly, according to this study, lactam-group were found in milk and dairy products in 133 (36.54%) studies, ofwhich only 75 penicillin (56.39%), 58 cephalosporins (43.61%) and thesmallest, 38 (10.44%) in the case of aminoglycosides Data indicate that theuse of antibiotic-lactam in milking animals is increasing day by day and thuscausing concern in this regard [36]

According to research by Sabbya Sachi (2019), 72 (32.14%) studiesshowed simultaneous detection of several antibiotics in a specific class; 71(31.69%) showed that the technique detects one antibiotic at a time; 64(28.57%) detected multiple layers and several antibiotics in each layersimultaneously The rest of the articles obtained, 16 (7.14%) were aboutdetecting multiple antibiotics classes, but only one in each class [36].

Beta2-agonists such as Clenbuterol (CLB), salbutamol (SAL), andractopamine (RAC) are substances used in the treatment of asthma andpremature birth in humans However, these substances have been abused inlivestock to proliferate muscle tissue instead of adipose tissue This abuse hascaused a number of severe poisoning cases in humans [37], [38] Thesesubstances have been banned for use in livestock production in somecountries Many studies have shown large residues of these substances inmeat, which harm human health; however, not many studies evaluated beta2-agonist residues in milk Cun Li (2010) did not detect clenbuterol in any ofthe evaluated milk samples [39] Another study in China found similar results,with no clenbuterol in the 60 studied milk samples [40] However, a study inTurkey recorded a high percentage of samples contaminated with clenbuterol,with 41/60 (68.4%) contaminated milk samples (21.7%) exceeding the EU’spermitted limit The mean value of Clenbuterol in the positive samples was86.51 ± 173.70 ng/L The minimum and maximum values are 0.15 and1052.90 ng/L, respectively [41] Polluting milk and dairy products withClenbuterol and other beta2-agonists is entirely possible regardless ofcontroversy between studies and although the number of studies on this issue

is limited

1.2.4 Pesticide residues contamination in milk and dairy products for children under 36 months

Food is the main way that pesticides enter the body food, especiallyrich-lipid animal source foods Some studies reported that animal sourcefoods are responsible for 90% of pesticides in the human body The largenumber and frequency of pesticides detected in recent surveys can beexplained by the more sensitive analytical methods A recent surveyconducted by the US Department of Agriculture in 2011 found that among

743 whole milk samples were analyzed, only 5 showed the existence ofpesticide residues, though lower than the level allowed by the USEnvironmental Protection Agency (EPA) [22]

Overall, research on pesticide residues in milk and dairy productscontinuously focuses on searching for organochlorine pesticides due to itshigh environmental durability and toxicity For organic phosphorus groups(Organophotpho pesticide) and carbamate (CB) pesticides, their residues inmilk and products are also recorded by many studies The frequency ofsamples positive for OPP and CB residues found by Nero et al was 196(93.8%) out of 209 raw milk samples in four Brazilian regions [42] In a study

in Spain, the percentage of milk samples contained detectable OPP residueswas 6.73% in total milk types and 8.67% in raw milk The highestpercentages measured were dichlorvos (5.78%), followed by coumaphos(2.06%) and methyl parathion (0.83%) The range of positive results is from0.005 to 0.220 mg/kg No residue was detected in the final product (infantformula) [43] Rafael Fagnani (2011) also found that 6 (20%) out of 30 rawmilk samples were contaminated with OPP, 5 (16.7%) were contaminatedwith CB, and one sample contained both pesticides [44]

1.3 The toxicity of some chemical contaminants in milk and dairy products

Milk and dairy products are the primary sources of nutrition, especiallyfor children, due to virtually all of the essential macronutrients andmicronutrients The most frequent consumers of milk and dairy products areinfants and the elderly The presence of any toxic substance in milk is of greatconcern In response, strict rules were applied to harmful materials in milkand dairy products

1.3.1 Toxicity of heavy metals in milk and dairy products

The toxicity of heavy metal is a major threat, and there are a number ofhealth risks associated with it Although they do not have any biological roles,the adverse effects of these metals still exist in some or other harmful forms

to the body They sometimes act as a dummy element of the body, while theycan even interfere with metabolic processes at certain times Very few metals,such as aluminum, can be removed through secretory activities, while some ofthem accumulate in the body and food chain, exhibiting chronic properties.Various methods have been taken to control, prevent, and treat metal toxicitythat occurs at different levels, such as occupational exposures, accidents, andenvironmental factors Toxicity of heavy metal depends on the absorbed dose,route of exposure and exposure duration, i.e., acute or chronic This can lead

to various disorders resulting in excessive damage due to oxidative stressinduced by free radical formation [45]

The main target organ of Pb poisoning is the nervous system Leadpoisoning causes the most consequential harm to children because they arestill in their developmental stages Other health effects of lead on the humanbody include hyperactivity, decreased immunity, anemia, and it is considered

a carcinogen in humans (group 2A) Cd is mainly found in the kidneys andliver, so Cd’s main target organ are these organs Cd toxicity is also linked to

a painful illness called Itai-Itai disease Furthermore, Cd exposure isattributed to bone demineralization, hypertension in pregnant women,impaired calcium metabolism, stone formation, and hypercalciuria It is saidthat the ingestion of As may lead to various cancers in humans, including skincancer, liver cancer, bladder cancer, and lung cancer Cardiovascular diseases,skin damage, digestive, respiratory and urinary disorders, andhyperpigmentation are some of the other major health effects of arsenicpoisoning Mercury has been reported to cause a number of disorders inhumans Nervous system disorders in Japan (the 1950s) and Iraq (1971-1972)are associated with the ingestion of methyl mercury [28] Hg can causeimpaired memory in children and various other disorders, includingreproductive, nervous, heart, genetics, motor, and immune system issues.

Heavy metal content in milk and dairy products at low concentrationshas not caused acute poisoning symptoms, but the central problem is the long-term impacts of aforementioned heavy metals

1.3.2 Toxicity of mycotoxins and Melamine in milk and dairy products.

The effects of certain mycotoxins from food are acute with severeillness symptoms, appearing rapidly after consuming food productscontaminated with mycotoxins Meanwhile, ingesting other mycotoxins infood has led to long-term health effects, including cancer andimmunodeficiency Of the hundreds of mycotoxins identified to date, about adozen have attracted the most attention due to their dangerous effects onhuman health and their presence in food

Aflatoxin is one of the most toxic substances produced by certain fungi

(Aspergillus flavus and Aspergillus parasiticus) that grow in soil, rotting

vegetation, hay, and grains The toxins can also be found in the milk ofanimals fed with contaminated food, in the form of aflatoxin M1 High doses

of aflatoxin can lead to acute poisoning (aflatoxicosis) and can be

life-threatening, usually through liver damage Aflatoxins have also been proved

to be genotoxic It means that they can damage DNA and cause cancer inanimals and liver cancer in humans [47]

Melamine is described as being harmful if swallowed, inhaled, orabsorbed through the skin It causes kidney and urinary problems and evendeath in newborn babies when it reacts with cyanuric acid in the body TheFDA reports that when melamine and cyanuric acid are absorbed into thebloodstream, they form rounded, yellow crystals that may block and damagekidney cells The toxic dose of melamine is as high as the one of NaCl saltwith LD50 over 3 grams per kilogram of body weight In 2008, in China,more than 50,000 infants were hospitalized, and 6 died after consuming babyformula contaminated melamine [30] Public concern was raised becauseNew-Zealand-based food-giant Fonterra learned from its Chinese partnerSanlu Group that infant formula was contaminated Sanlu, working with theChinese health authorities, then instituted a full public recall of the affectedformula [46]

1.3.3 Toxicity of veterinary drug residues in milk and dairy products.

Residues of vet drugs in milk have been a major concern of the public

as milk is being widely consumed by infants, young children, and adultsglobally

Residues of veterinary drugs can cause acute and chronic side effects.Some of the acute and chronic side effects of veterinary drug residues havebeen mentioned, such as human antibiotic-resistant, autoimmune,carcinogenic (Sulphamethazine, Oxytetracycline), mutagenicity, kidneydisease (Gentamicin), hepatotoxicity, fertility disorder, bone marrowintoxication (Chloramphenicol), or allergies (Penicillin) These hazards can beclassified into two categories as short-term direct hazards and long-termindirect hazards, according to residue exposed time and time of onset of

health effects Direct health hazards are the health effects caused by drugsecretion in milk For example, a group of beta-lactam antibiotics, regardless

of low milk concentrations, can cause anaphylactic hypersensitivity reactions

in individual sensitivities immediately after consumption In contrast, chronictoxic effects occur after prolonged exposure to low levels of antibiotics,including carcinogenicity, teratogenicity, reproductive effects, development

of antibiotic-resistant bacteria in treated animals, and disruption of normalhuman flora in the gut Chronic exposure to OTC also includes blood changessuch as leukocytosis, atypical lymphocytes, pulmonary obstruction, toxicgranulation of agranulocytosis and thrombocytopenia, and browndiscoloration teeth Antimicrobial agents such as tetracycline, nitrofurans, andsulfonamides used as feed additives in forage can be excreted in milk andhave sometimes been associated with toxic effects in humans [48]

1.3.4 Toxicity of pesticide residues in milk and dairy products.

Pesticides are potentially toxic to other non-targeted organisms,including humans Toxicity of chemical, duration, and intensity of exposuredetermine the magnitude of the impact on human health The effects of toxicchemicals also depend on the route of exposure (oral, skin, and respiratorytract), the dose, and the organism The toxicity of pesticide residues can beacute or chronic

Chronic effects

Continuous and repeated exposure to lethal doses of plant protectiondrugs for a long time (possibly years to decades) causes chronic effects.Symptoms are not noticeable immediately but appear at a later stage.Suspected chronic effects due to exposure to certain pesticides includecongenital disabilities, fetal toxicity, and benign or malignant tumorproduction, genetic changes, blood disorders, neurological disorders,endocrine disorders, and kidney, reproductive, cardiovascular, and respiratorysystem

1.4 Some characteristics of the research locality.

Hai Phong is a port city, the largest industrial and seaport center in theNorth of Vietnam, and the economic, cultural, medical, educational,scientific, commercial, and technological center of the Northern coastalregion It is the 3rd largest city in the country, the 2nd largest in the Northafter Hanoi Hai Phong is also one of five centrally-controlled cities, anational level 1 center, along with Da Nang and Can Tho Hai Phong hasmany large industrial, commercial and service, tourism, educational, healthand fishery centers in Vietnam’s northern coastal region Hai Phong is acrucial part of the North of Vietnam’s key economic triangle including Hanoi,Hai Phong, and Quang Ninh

Hai Phong is the third most populous city in Vietnam, with apopulation of 1.963 million, encompassing 1,561.8 km2 Hai Phong cityincludes seven urban districts, six suburban districts, and two island districts;(223 communal units include 70 wards, 10 towns, and 143 communes)

Currently, Hai Phong is one of the most important economic centers ofVietnam, and since 2005 it has always ranked in the top 5 cities contributingthe most to the national budget, notabl always ranked in third place after HoChi Minh City and Hanoi In 2015, the total budget revenue of the city

reached 56,288 billion In 2016, the budget revenue was 62,640 billion VND.State budget revenue in 2018 reached 70,730.5 billion VND In the ranking ofVietnam's Provincial Competitiveness Index in 2017, Hai Phong city ranked9th out of 63 provinces.

Hai Phong's domestic revenue during the term of Secretary Le VanThanh in the period of 2014 - 2017 increased impressively, specifically by 2.4times after only three years (2014 - 2017), and reached three years ahead ofthe plan (Hai Phong advocates domestic revenue of 20 trillion by 2020 but in

2017 it reached 22 trillion) In 2018, the domestic revenue of Hai Phong cityreached 24,768 billion VND In the process of deep and broad integration ofthe country, with historic free trade agreements signed such as the Trans-Pacific Partnership Agreement, the establishment of the ASEAN Community

is a great developmental opportunity for Hai Phong Currently, Hai Phongcity has been an attractive investment destination for foreign investors, aseries of large FDI projects focusing on high-tech, low-pollution industriessuch as LG Electronics 1.5 billion USD; Bridgestone 1.2 billion USD, LGDisplay 1.5 billion USD and many other big names such as Regina Miracle,Fuji Xerox, Kyocera, Nipro Pharma, GE showed great attraction of the city.The project VinFast Automobile and Electric Motorcycle Factory complex ofVingroup, the factory has an area of 335 hectares with a total investment of3.5 billion USD With the ambition to develop into a ‘Made In Vietnam’ automanufacturing brand, VinFast has invested, cooperated, and purchasedtechnology and engineering copyrights with major European automobile andspare parts manufacturers BMW, Siemens AG and Robert Bosch GmbH ofGermany, Magna Steyr of Austria, and Italian design firm Pininfarina areamong the largest industrial project complexes in Vietnam and machinery,equipment, the modern robot systems on top of Southeast Asia

Big corporations such as Vingroup, Himlam, Hilton, Nguyen Kim,Lotte, Hiep Phong Group (Hong Kong), Apage (Singapore) have brought intoHai Phong big projects in recent years Vingroup delivered a $ 1 billion eco-tourism project in Vu Yen Island (800ha), project Vincom Le Thanh Tong;Vinhomes Imperia with 45-storey tower, Vinmec hospital project, Vinfast carfactory in Cat Hai island, Vin-Eco hi-tech agricultural project Otherexamples include the 65-game park tourist area in Dua Island from Himlam,5-star Hilton Tran Quang Khai, Ourcity Urban Area and International TradeCenter of Alibaba Group, Aeon Mall, Water Front Urban Area, and otherprojects such as Hoa Phuong Island, Dragon Hill in Do Son for See werepromising signs of the city's development in tourism and service

Hai Phong is the largest import-export channel distribution center in theNorth Up to now, Hai Phong has import and export relations with over 40countries and territories around the world Hai Phong International ExpoCenter is the largest fair center in Vietnam today Hai Phong is striving tobecome one of the largest commercial centers in Vietnam.

Chapter 2 SUBJECTS AND METHODS OF RESEARCH 2.1 Subject, location, and time

+ Liquid milk products: Pasteurized fresh whole milk and pasteurizedfresh milk, pasteurized fresh whole milk, pasteurized fresh milk andpasteurized milk, Condensed milk (condensed milk) and fortified condensed

skim milk suppled vegetable fat (condensed milk with added vegetable fat)(QCVN 05-1:2010/BYT).

+ Cheese products: Cheese made from raw fresh milk, Cheeseproduced from heat-treated milk, Cheese (made from heat-treated whey),Cheese produced from milk, other cheese types (according to QCVN 05-3:2010/BYT)

+ Fatty dairy products: Cream liquid, butter, milkfat and butter oil,anhydrous milkfat and anhydrous butter oil, Milkfat spread (according toQCVN 05-4:2010/BYT)

+ Fermented milk: fermented milk products with heat treatment, milkwithout heat treatment (QCVN 05-5:2010/BYT)

2.1.2 Location and time of study

- Location:

+ Research site in the field: research is conducted in Hai Phong city+ Test locations: Labo Military Department of Hygiene and ResearchInstitute of Medicine and Pharmacy, Vietnam Military Medical University

- Time: from August 2019 to August 2020

2.2 Methods

2.2.1 Study design

- Cross-sectional descriptive research, with analysis:

+ Describing polluted levels of some common chemical in milk anddairy products for children under 36 months

2.2.2 Sample size, sample selection

+ Powdered milk products: 50 samples.

+ Liquid milk products: 50 samples

+ Cheese products: 50 samples

+ Dairy fat products: 50 samples

+ Fermented milk: 50 samples

Thus, the sample size of the food groups intended for children under 36months is 250 samples

* Sampling method:

Selecting milk and dairy products for children under 36 months of age:

Milk and powdered milk products: Being divided into four groups:

Milk powder, Cream powder, Skim milk powder with added vegetable fat,and Whey powder (QCVN 05-2:2010/BYT)

In each group, choose 10-15 products most commonly consumed in thestudy area (based on the City Food Safety Bureau) Each commercial producttakes 1 sample Specifically: Milk powder (15 samples), Cream powder (15samples), Skim milk powder added vegetable fat (10 samples), and Wheypowder 10 samples

Milk and liquid milk products: Being divided into four groups:

Pasteurized Milk, Pasteurized Milk, Condensed Milk, and Concentrated SkimMilk (QCVN 05-1: 2010/BYT)

In each group, choose 10-15 products most commonly consumed in thestudy area (based on the City Food Safety Bureau) Each commercial producttakes 1 sample Specifically: 15 samples of pasteurized milk, 15 samples ofpasteurized milk, 10 samples of condensed milk, and 10 samples ofcondensed skim milk

+ Cheese products: choose the 50 most popular commercial cheese

products in the study area (based on the City Food Safety Sub-Department)

+ Dairy fat products: Being divided into four groups: Liquid Cream,

Butter, Milk Fat and Butter Oil, and Milk Fat spreads (QCVN 05-4:2010/BYT)

In each group, choose 10-15 products most commonly consumed in thestudy area (based on the City Food Safety Bureau) Each commercial producttakes 1 sample Specifically: 10 samples of liquid cream, 15 samples ofbutter, 10 samples of milk fat and butter oil, and 15 samples of dairy fat

+ Fermented dairy products: select 50 commercial fermented dairy

products that are most commonly consumed in the study area (based on datareported by the City Food Safety Bureau)

2.2.3 Content and research criteria

Evaluation methods:

+ Milk and powdered dairy products: being assessed according to themaximum limit of chemical contamination according to QCVN05-2:2010/BYT

+ Milk and liquid dairy products: being assessed according to themaximum pollution limit of chemical criteria according to QCVN 05-1:2010/BYT

+ Cheese-type products: being evaluated according to the maximumchemical limit pollution limit according to QCVN 05-3:2010/BYT

+ Dairy fat products: being evaluated according to the maximumchemical limit pollution limit according to QCVN 05-4:2010/BYT.

+ Fermented milk products: being assessed according to the maximumlimit of chemical contamination according to QCVN 05-5:2010/BYT

2.2.3.2 Research criteria and method of determination

+Method of determining the content of heavy metals in milk and dairyproducts for children under 36 months:

Concentration of Lead (Pb) (mg/kg); Tin (Sn) (mg/kg); Arsenic (As)(mg/kg); Cadmium (Cd) (mg/kg); Mercury (Hg) (mg/kg)

Determination method: Atomic absorption spectrometric method afterdry ashes using the AAS ZA-3000 system at the Department of MilitaryHygiene

- Ashes

Place the dish in the oven at an initial temperature not higher than100°C Increase the temperature from a maximum of 50°C to 450°C Let the

dish sit for at least 8 hours or overnight.

- Atomic absorption spectrometry using graphite furnaces

Choose the wavelengths, temperature programs, and otherspecifications appropriate for each metal arcording to the equipmentmanufacturers’ manuals

In flame-free atomic absorption spectrometry, background correction isrequired

When results are out of the linear range, dilute the test solutions with0.1M nitric acid solution

Always use the standard addition method Measurements shall be made

in a linear range using the standard addition method It is better to takemeasurements with the peak area than using peak heights

- Calculating and denoting the results

Calculate the metal content in the test sample, X, expressed inmilligrams per kilogram (mg/kg), using the formula:

There:

C is the metal concentration in the test solution (mg/l);

C0 is the average concentration of the metal in the blank test solution(mg/l);

V is the volume of the test solution (L);

m is the mass of the test portion (g)

If the test solution was diluted, include the dilution factor in thecalculation

When performing a repeat determination, use the average of resultswith two decimals

+ Method of determining residues of pesticides in milk and dairyproducts for children under 36 months

Original standard solution of pesticide substances 1000 ppm: accuratelyweigh 0.0100g of each pesticide standard into 10ml separate volumetricflasks, dissolve with methanol and make up to volume with methanol Thesolution is stored in the -220C freezer Shelf-life is 12 months

TPP original standard solution 1000 ppm: accurately weigh 0.0100gTPP into a 10ml volumetric flask, dissolve with methanol and make up tovolume with methanol The solution is stored in the -220C freezer Shelf-life

is 12 months

Note: The above weight must be appropriately adjusted after calculating and calibrating the weight according to the manufacturer's certificate.

Intermediate standard solution of pesticides 100 ppm: take precisely 1

ml of a standard solution of 1000 ppm into separate 10 ml volumetric flasks,make up to volume with acetonitrile The solution is stored for -220C, theshelf life is 6 months

Mixed working standard solutions of 10 ppm: take suitable volumes of

100 ppm intermediate standard solutions to prepare a mixed working standardsolution with a concentration of 10 ppm in acetonitrile Store solution 2 – 80C,shelf-life 1 week

Mixture of working standard solutions 1 ppm: accurately suck 1 ml of

10 ppm working the standard mixture into a 10ml volumetric flask, addacetonitrile and make up to the mark, cover, mix well Store the solution at 2– 80C, shelf-life 1 week

TPP 100 ppm intermediate standard solution: aspirate precisely 1 ml of

TPP 1000 ppm standard solution into a 10ml volumetric flask, add

acetonitrile, and make up to volume, cover, mix well Store the solution at

-220C, expiry date 1 year

TPP 1ppm working solution: suck exactly 100µL of the 100 ppm TPP

intermediate standard solution into a 10 ml volumetric flask, add acetonitrileand make up to volume, cover, mix well Store the solution at 2 - 80C, shelf-life 1 month

Mobile phase solution A: aspirate exactly 500µL of dissolved formic

acid into 500 mL acetonitrile Store at room temperature The shelf life of thesolution is 1 month

Mobile phase solution B: aspirate exactly 500µL of dissolved formic

acid into 500 mL acetonitrile Store at room temperature The shelf-life of thesolution is 1 month

Standard solution for testing machine: Aspirate exactly 100µL of

pesticide standard 1ppm and 100 µL of TPP working standard, addacetonitrile to get 1mL of standard solution for testing machine

ANALYSIS PROCESS

Prepare the raw sample

For milk samples, baby food: Crush finely and homogenize the wholesample

Prepare the test sample

Weigh 5.00 ± 0.05 g of homogenized sample for which with high watercontent and 2.00 ± 0.02 g for low water content, add 250 µL to a 50 mL TPPworking solution 1 ppm into a plastic tube, vortex 30 seconds

Prepare the blank sample

The blank (checked without analyte) is prepared in the same way as thetest sample

Prepare a control sample

Control samples are prepared in the same way as the test samples butadded 500µL of 1 ppm working standard solution, 30 s vortex

Samples added standard concentration to build standard curves

The sample added standard concentration is prepared in the same way

as the blank Pesticide standard solutions 1ppm and 10 ppm, TPP workingstandard solutions 1 ppm into tubes containing blank samples according to thefollowing table, then mix well on vortex for about 30 seconds

Std 1 10 ppb

Std 2 50 ppb

Std 3 100 ppb

Std 4 150 ppb

Std 5 200 ppb

Std 6 250 ppb

QC 100 ppb

Blan k

For samples with high water content: add 20ml of acetonitrile solution

to tubes containing blank, test, control, stopper, mix for 1 min on the vortex

For samples with low water content: add 10 ml H2O, vortex for 1minute, then add 10 ml acetonitrile, mix for 1 minute on the vortex machine

Pour the entire mixture M1 into the falcol tubes containing the sampleabove, cover carefully, mix well on the vortex for 30 seconds

Centrifuge the sample at 5.000 rpm for 5 minutes

Aspirate about 4 ml of the upper layer solution into the falcol tubecontaining the M2 mixture, mix well on the vortex machine

Centrifuge the sample at 5.000 rpm for 5 minutes

Aspirate 1 ml of filtrate through a 0.22 µm membrane filter, run the LC

- MS/MS machine

% Mobile phase B(0.1% AF/H2O) Curve

Desolvation gas flow 0.25 mL/min

Cone gas flow OFF

+Methods of determining antibiotic residues in milk and dairy products for children under 36 months

Sample treatment:

Weigh 10g of baby food into a 50ml centrifuge tube Add 20 ml ofEtOAc and shake vigorously for 10 minutes or, if necessary, mix vortex tocreate a suspension Centrifuge at 3000 rpm for 5 minutes Decant the EtOAcportion to a clean tube Add 20 ml of EtOAc, shake, and mix for 1 minute,centrifuge 3000 rpm for 5 minutes Decant the EtOAc portion and merge itwith the above Then evaporate it Add 2 ml of MeOH, shake to get dissolvedand transfer to 50ml tube Dissolve with 4% NaCl to 25ml Add 20 ml of

hexane, stopper tightly, mix until almost all colors are in the hexane layer Toseparate layers, aspirate, and decant the hexane (in 2 times) Add 15 ml ofEtOAc to a 50 ml centrifuge tube, close tightly, and shake the vortex Toseparate phase (do 2 times), filter the upper EtOAc layer through a filterfunnel with glass wool and 3-10g Na2SO4 or MgSO4 into a clean tube Washthe funnel with 5ml EtOAc Combine EtOAc translation The solventevaporates with a stream of nitrogen to dryness Add 5 ml of methanol todissolve the residue, filter through a 0.2 μm filter, inject into LC/MS/MS.

Weigh, to the nearest 0,01g, 10g into a 250ml beaker Take 50ml ofwater warmed to 50°C in a water bath and add slowly to the formula Stirwith a stick until a homogeneous mixture is obtained.

If the test samples are not fully dissolved, place the beaker in a waterbath set at 50°C for at least 30 minutes Mix well

Cool the solution to a temperature between 20°C and 25°C Transfer to

a 100ml volumetric flask with a little water Dilute to the 100ml line withwater Filter the reconstituted milk through filter paper or centrifuge at 2.000gfor 15 min Collect at least 50ml of milk Follow the sample extraction andpurification procedure

- Preparing an immunotropic chromatographic column

Attach a 50ml disposable syringe to the top of the immunogenicitychromatographic column Connect the bottom of the column to the vacuumsystem

- Extracting and purifying the test sample

Use a pipette to take 50ml of the prepared test sample into a 50mlsyringe Pass the immune avidity chromatographic column at a steady slowspeed of 2 ml/min to 3 ml/min Use a vacuum extraction system to control theflow speed

Remove the 50ml syringe and replace it with a clean 10ml syringe.Wash the column with 10ml of water by passing the column at a constantflow speed After cleaning, blow the column to dry completely

Remove the column from the vacuum system Elute the aflatoxin M1slowly from the column using a 10ml syringe and passing 4ml of pureacetonitrile through the column for approximately 60 seconds Use theplunger of the syringe to control the flow speed

Collect the eluate in a conical tube Reduce the eluate volume to thevolume, Ve, between 20µl and 500 µl by placing the tube in a pot set at 30°C

and gently blowing a stream of nitrogen gas on the tube.

- High-performance liquid chromatography

+ Preparing the pump

Pump the eluate solvent at a constant flow rate through the HPLCcolumn Depend on the type of column used, the acetonitrile/water ratio of theHPLC eluate, if necessary, may be adjusted to ensure that aflatoxin M1 iscompletely removed from the other components

+ Running chromatography

Check the chromatographic system’s stability by repeatedly injecting afixed amount of aflatoxin M1 working standard solution until reaching aconstant peak area or peak height Successive injections shall differ by morethan 5% from peak area or peak height

The retention time of the aflatoxin M1 peaks depends on thetemperature Consequently, the detector system’s bias must be corrected byinjecting a fixed quantity of aflatoxin M1 standard working solution regularly

If necessary, the results of the working standard solutions can be corrected forbias

- Constructing the standard curve of aflatoxin M1

Inject the aflatoxin M1 standard working solutions, depending on theinjection ring volume, in turn, taking appropriate volumes containing 0.05ng,0.10ng, 0.20ng, and 0.40ng aflatoxin M1, respectively, into HPLC Create astandard according to peak area or peak height for each original workingsolution corresponding to the mass of aflatoxin M1 injected

Determine the area or peak height of the aflatoxin M1 of the sampleeluate Based on a standard graph, determine the mass of aflatoxin M1 innanograms in the volume of the sample extract injected

If the peak area or the peak height of the aflatoxin M1 in the sampleelution solvent is greater than the peak area or peak height of the highest

standard solution, dilute the eluting solvent quantitatively with water Refillthe diluted extract into the HPLC, as described above.

- Calculating the results

Calculate the aflatoxin M1 content of the test sample, as the mass of thetest portion, w, in micrograms per kilogram, using the formula:

Chapter 3 RESULTS 3.1 Level of some heavy metals polluted in milk and dairy products for children under 36 months in Hai Phong, 2020

3.1.1 Lead (Pb) level in milk and dairy products intended for children under 36 months

Table 3.1 Lead (Pb) level in milk and dairy products intended for

children under 36 months

Products (mg/kg)X± SD (mg/kg) Median (mg/kg) Max Permitted limit

Powder milk

products

(n=50)

Powder milk (n=15) 0.009 ± 0.008(0/15) 0.012 0,020

≤0.02 mg/kg

Powder Cream (n=15) 0.008 ± 0.007(0/15) 0.005 0.019Skim powder

milk added vegetable fats (n=10)

0.011 ± 0.007 (0/10) 0.0145 0.019Powder Whey

≤0.02 mg/kg

Sterilized milk (n=15) 0.008 ± 0.007(0/15) 0.005 0.019Condensed milk

(n=10) 0.010 ± 0.006(0/10) 0.0095 0.019Condensed Skim

≤ 0.02 mg/kg

Butter (n=15) 0.007 ± 0.007(0/15) 0.007 0.018Milk fat and

avocado oil (n=10)

0.006 ± 0.007 (0/10) 0.004 0.018Milk fat spreads

(n=15) 0.006 ± 0.007(0/15) 0.004 0.019

Fermented milk (n = 50) 0.009 ± 0.011(1/50) 0.006 0.067 ≤ 0.02 mg/kg

Comment: Average lead (Pb) content in milk and dairy products for childrenunder 36 months ranged from 0.006 - 0.010 mg/kg, in which Skim powder

milk added vegetable fats had the highest median (0.0145mg/kg) There were1/50 samples of fermented milk products with Pb content exceeding thepermitted value threshold (0.067 mg/kg)

3.1.2 Tin (Sn) level in milk and dairy products intended for children under 36 months

Table 3.2 Tin (Sn) level in milk and dairy products intended for children

≤ 250 mg/kg

Powder Cream (n=15) 67.27 ± 81.89(0/15) 13 191Skim powder

milk added vegetable fats (n=10)

93.10 ± 87.32

Powder Whey (n=10) 69.20 ± 62.07(0/15) 72 162

Liquid milk

products

(n=50)

Pasteurized milk (n=15) 104.93 ± 88.30(0/15) 126 217

≤ 250 mg/kg

Sterilized milk (n=15) 50.47 ± 46.50(0/15) 50 153Condensed milk

(n=10) 102.60 ± 71.24(0/10) 118,5 228Condensed Skim

≤ 250 mg/kg

Butter (n=15) 42.47 ± 23.54(0/15) 50 76Milk fat and

avocado oil (n=10)

products (1 sample of liquid milk product, 2 samples of cheese products, and

1 sample of dairy products) with a tin (Sn) content exceeding the permittedvalue threshold

3.1.3 Asen (As) level in milk and dairy products intended for children under 36 months

Table 3.3 Asen (As) level in milk and dairy products intended for

children under 36 months

Products (mg/kg)X± SD Median (mg/kg) (mg/kg) Max Permitted limit

Powder milk

products

(n=50)

Powder milk (n=15) 0.16 ± 0.14(0/15) 0.18 0.37

≤ 0.5 mg/kg

Powder Cream (n=15) 0.20 ± 0.12(0/15) 0.27 0.34Skim powder

milk added vegetable fats (n=10)

0.18 ± 0.14

Powder Whey (n=10) 0.24 ± 0.10(0/10) 0.265 0.34

Liquid milk

products

(n=50)

Pasteurized milk (n=15) 0.16 ± 0.13(0/15) 0.17 0.32

≤ 0.5 mg/kg

Sterilized milk (n=15) 0.16 ± 0.16(0/15) 0.17 0.42Condensed milk

(n=10) 0.14 ± 0.15(0/10) 0.145 0.41Condensed Skim

≤ 0.5 mg/kg

Butter (n=15) 0.20 ± 0.17(0/15) 0.23 0.46Milk fat and

avocado oil (n=10)

was a 1/50 sample of cheese products with As content exceeding thepermitted value threshold (0.51 mg/kg).

3.1.4 Cadmium (Cd) level in milk and dairy products intended for children under 36 months

Table 3.4 Cadmium (Cd) level in milk and dairy products intended for

children under 36 months

Products (mg/kg)X± SD (mg/kg) Median (mg/kg) Max Permitted limit

Powder milk

products

(n=50)

Powder milk (n=15) 0.27 ± 0.32(0/15) 0.13 0.90

≤ 1.0 mg/kg

Powder Cream (n=15) 0.37 ± 0.38(0/15) 0.36 0.97Skim powder

milk added vegetable fats (n=10)

0.22 ± 0.17 (0/10) 0.265 0.45Powder Whey

≤ 1.0 mg/kg

Sterilized milk (n=15) 0.18 ± 0.26(0/15) 0.5 0.82Condensed milk

(n=10) 0.35 ± 0.29(0/10) 0.335 0.86Condensed Skim

≤ 1.0 mg/kg

Butter (n=15) 0.32 ± 0.35(0/15) 0.18 0.86Milk fat and

avocado oil (n=10)

0.34 ± 0.26 (0/10) 0.425 0.62Milk fat spreads

(n=15) 0.23 ± 0.30(0/15) 0.02 0.87

Fermented milk (n = 50) 0.33 ± 0.35(1/50) 0.255 1.19 ≤ 1.0 mg/kg

Comment: Average cadmium (Cd) content in milk and dairy products forchildren under 36 months ranged from 0.18 to 0.54 mg/kg, in whichpasteurized milk products have the highest median (0.53 mg/kg) There were2/250 product samples (1 cheese product and 1 fermented milk product) with