Analysis of Lead (Pb) and Cadmium (Cd) heavy metals in cow’s milk in Central Java, Indonesia

The need for animal food is increasing because of its nutritional content. Foodstuffs needed to meet daily needs must be healthy and free from harmful substances, including heavy metals. Fresh cow’s milk is an animal-based food that is consumed by many people because it is very easy to find at an affordable price. This study aimed to determine the levels of heavy metals Pb (Lead) and Cd (Cadmium) contained in fresh cow’s milk and to find recommendations if they exceed a predetermined threshold. The method used is laboratory analysis of heavy metal content in fresh cow’s milk from a cattle farm in Boyolali Central Java. Analysis of Pb and Cd content was carried out by Atomic Absorption Spectroscopy (AAS). Data analysis was carried out by comparing the content of heavy metals in fresh cow’s milk with SNI 3141.1: 2011 concerning quality requirements for fresh cow’s milk and SNI 7387: 2009 concerning the maximum limit of heavy metal contamination in food. Laboratory test results on fresh cow’s milk had a heavy metal Pb content of 96.67 mg/kg and a heavy metal Cd content of 4.45 mg/kg. It is known that the maximum limit for heavy metal contamination in food is 0.02 mg/kg. It can be concluded that the heavy metal content in fresh cow’s milk has exceeded the existing quality standard threshold. Previous research revealed that the metal lead content in cow’s milk that has been processed is lower than in cow’s milk that has not been processed.


Introduction
One of the animal-based food ingredients that contain a good nutritional value for human consumption is milk [1].Cow's milk has quite a potential opportunity in product development.Cow's milk is popular with the wider community because of its beneficial nutritional content in it.Fresh cow's milk is a liquid produced from the udders of healthy and clean cows from proper milking, its natural content is still pure without being reduced or added to anything.Foodstuffs are free from the possibility of biological, chemical, and other contamination that can interfere with, harm, and threaten human health, and do not conflict with religion, beliefs, or community customs, so they are suitable and safe for consumption [2].Milk is one of the natural foods produced by the mammary glands of mammals and is widely consumed by the public to meet nutritional needs.With a complete nutritional content, milk has an important role as food for health, intelligence, and growth, especially the growth and development of children [3].Fresh cow's milk is a type of milk that is often consumed by the public.This is because besides being easy to obtain and having high nutritional content, fresh cow's milk is also relatively affordable.In a study conducted by [4], Cow's milk comes from dairy cows which contains a source of protein, fat, carbohydrates, minerals, and vitamins.
The quality of food and food ingredients in nature cannot be separated from various influences, such as environmental conditions which are a benchmark for food to obtain eligibility for consumption [5].The quality of milk will decrease if there are contaminants in it.Cow milk can be contaminated with heavy metals from the environment, such as Pb and Cd.Milk contamination can be caused by several things, such as microbes, pesticide residues, and heavy metal buildup.Research by [6], states that heavy metal contamination of Pb is very dangerous for consumers of meat and milk from cows that are contaminated with heavy metals.Heavy metal contamination in the cow's body can occur due to organic rearing because heavy metals can come from feed or drinking water that contains a lot of heavy metals.
Heavy metals are metallic and metalloid chemical components with high atomic weights and specific gravity, which can be toxic to living things.Heavy metals such as cadmium (Cd) and lead (Pb) are not essential elements and have no biological role, but at very low concentrations they can cause toxic effects [7].Lead metal (Pb) can enter foods such as milk and processed products [8].Lead (Pb) is a type of heavy metal with toxic properties that easily accumulate in organs, making it very dangerous for human life [9].This is because lead can cause disturbances in kidney function, anemia, the reproductive system, and the nervous system.The maximum content of lead metal according to BPOM RI Number 5 of 2018 is 0.02 mg/kg (BPOM, 2018).The maximum lead content allowed in fresh cow's milk is 0.02 µg/ml (National Standardization Agency, 2011).According to [10], lead toxicity will be seen if an individual consumes food or drink that has a lead content of more than 2 mg/day because the threshold for lead that may be consumed is 0.2 -2.0 mg/day.Meanwhile, cadmium (Cd) is a type of heavy metal that is very dangerous because it has a higher risk of damage to blood vessels and can accumulate in other organs such as the liver and kidneys [9].The same thing was also conveyed by [11], the accumulation of cadmium will trigger damage to the liver.
Cd and Pb have properties that cannot be broken down by biological processes and if they accumulate in the environment they will be harmful to agriculture and public health [12].The presence of heavy metal deposits in fresh cow's milk can cause poisoning if the concentration exceeds the requirements of SNI 3141.1 (SNI 2016), Pb content has a maximum limit of 0.2 ppm, Hg 0.03 ppm, and a maximum limit of As 0.1 ppm [13].Research by [14], shows that the heavy metal Pb has spread throughout the body tissues of Bali cattle, including muscle tissue or meat which is the part that is mostly consumed by the community.This can allow the spread of heavy metals in the udder tissue of cows that produce milk.Another study stated that milk originating from dairy farms in Kebon Pedes Village, Bogor had no detectable presence of Pb and As metals, where the values were still included in the maximum residue limits according to SNI 01-3141-1998 [15].Therefore, efforts are needed to control the quality of cow's milk [16], so that the quality is maintained.
Based on this background, it is necessary to conduct research to determine the content of Pb and Cd in fresh cow's milk according to the Indonesian National Standard.This study aims to determine the content of heavy metals Pb (Lead) and Cd (Cadmium) in Boyolali cow's milk and provide recommendations if the Pb and Cd values exceed a predetermined threshold.

Time and Location of Research
This research was conducted from March to May 2023.The research sample was obtained through observation at a cattle farm in Boyolali Regency to obtain samples of fresh cow's milk directly from the producer (Figure 1).Sample preparation was carried out at the Laboratory of Soil Chemistry, Faculty of Agriculture, Sebelas Maret University.Analysis of the heavy metals Lead (Pb) and Cadmium (Cd) in the samples was carried out at the UPT Sebelas Maret University, Integrated Laboratory Chemistry sub-laboratory.

Testing for Heavy Metal Levels
Samples of fresh cow's milk and standard solutions were prepared first, then tested using AAS (Atomic Absorption Spectrophotometry ).Based on the tests that have been carried out, it is known that at a concentration of 0.05 ppm it has an absorbance of 0.00009, at a concentration of 0.1 ppm it has an absorbance of 0.00028, at a concentration of 0.25 ppm it has an absorbance of 0.00026, at a concentration of 0.5 ppm it has an absorbance of 0.00019, and at a concentration of 1 ppm it has an absorbance of 0.00037.The highest absorbance value is located at a concentration of 1 ppm.There are differences in absorbance values at each concentration tested.This absorbance value will depend on the level or substance contained in a solution.The more levels of a substance in a sample, the greater the absorbance value because more molecules will absorb light.Meanwhile, the metal content of Pb in fresh cow's milk was 96.67 mg/kg.From the research that has been done, it is known that at a concentration of 0.05 ppm it has an absorbance of -0.00041, at a concentration of 0.1 ppm it has an absorbance of 0.00004, at a concentration of 0.3 ppm it has an absorbance of 0.00024, at a concentration of 0.5 ppm it has an absorbance of 0.0004, and at a concentration of 1 ppm it has an absorbance of 0.00108.The content of Cd metal in fresh cow's milk is 4.45 mg/kg.Table 3 shows that the Pb level in the fresh milk sample was 96.666 mg/kg.This figure has exceeded the quality standard limits in SNI 3141.1:2011 concerning Requirements for the Quality of Fresh Cow's Milk and SNI 7387: 2009 concerning Maximum Limits of Heavy Metal Contamination in Food, which is 0.02 mg/kg.From the table, it was also found that the Cd level in the fresh milk sample was 4.45 mg/kg.This figure has exceeded the quality standard according to SNI 7387: 2009 concerning the Maximum Limit of Heavy Metal Contamination in Food, which is 0.02 mg/kg.From the tests carried out, it was found that the fresh milk samples tested were contaminated with heavy metals.

Comparison of Pb and Cd Concentrations with Pasteurized Cow's Milk
Pasteurized milk is milk that has undergone a processing process in the form of heating to a temperature of around 30-60 degrees in a span of 30 minutes.This pasteurization method is considered to kill germs and aims to eliminate microbes or bacteria present in milk [17].In the research conducted by [8], regarding the lead test on pasteurized milk with 3 samples, it was found that the lead content in pasteurized milk was below the quality standard of 0.02 mg/kg.The lead content in sample A was <0.001 mg/kg, sample B was 0.02 mg/kg, and sample C was <0.001 mg/kg.This is when compared with samples of fresh cow's milk that have not received any processing at all, the results will be much different.From the research that has been done, there is a lead content of 96.66666667 mg/kg which exceeds the quality standard.In the research conducted by [18], for fresh cow's milk which was also not processed, lead levels were found to exceed the quality standard, namely sample A of 0.0570, sample B of 0.1230, and sample C of 0.0380.This indicates that cow's milk is safer to consume when it has been treated, such as pasteurization or heating.As for cadmium, there is still no research on the cadmium content in processed cow's milk.

Lead (Pb) Contamination Process in Cow's Milk
Lead (Pb) is a heavy metal that is toxic and harmful to health.Lead can be produced naturally by the environment or by human activities such as in the transportation sector.Lead can pollute the air through the exhaust gasses released by the exhaust of fossil-fueled motor vehicles [19].The industrial sector which continues to develop in the utilization of heavy metals also has high potential as a source of lead pollutants in the air [20].The most common contamination of the heavy metal lead in cow's milk results from plant feed sources contaminated with lead.This is because plants have the ability to absorb contaminants such as lead, minimize pollution, and absorb dust [21].Plants can absorb the heavy metal lead because it has a binding compound (chelate) called phytochelatin [22].The heavy metal lead which is absorbed from the air by plants is then distributed to other plant parts through the xylem tissue.Plants contaminated with lead can be consumed by cattle resulting in the transfer of the heavy metal lead into the cow's body and can reduce the quality of the milk produced.This is because contamination of the heavy metal lead in the body of the cow will be secreted through milk [15].

Cadmium (Cd) Contamination Process in Cow's Milk
Cadmium (Cd) is a type of heavy metal that is very dangerous because it is carcinogenic and mutagenic [23].Cadmium is commonly found in industrial areas such as metal processing, textiles, paint, batteries, and others [24].Cadmium can pollute the environment from the process of disposing of cadmiumcontaining waste without processing it first.Cadmium pollutants can spread because they are carried by wind and water [25].If the cadmium pollutant reaches the cattle breeding area, it can enter the bodies of cows that drink water contaminated with cadmium.In addition, heavy metal cadmium can also contaminate the soil as a result of the application of chemical fertilizers and pesticides [26].Even in small amounts, cadmium contamination in the soil can contaminate plants used as feed for cattle [27].Cattle that consume plant feed grown on cadmium-contaminated soil can accumulate cadmium in their body tissues, including in the milk they produce [28].

Impact of Pb and Cd on Human Health
Heavy metals have certain mechanisms to enter the human body, such as ingestion, skin absorption, and inhalation.[29] stated that the effects of heavy metals on the health of children are more severe than those of adults.Lead exposure in children affects their learning abilities and behavior [30].High levels of lead exposure cause children to be hyperactive, irritable, and lack concentration levels in the central nervous system, making them more susceptible to seizures, epilepsy, headaches, and even death [31].In adults, exposure to lead has an impact on body systems with symptoms that are not very specific, such as decreased cognitive function, miscarriage in women, and infertility in men [29].Lead exposure in pregnant women can harm the developing fetus. in the womb including premature birth, low birth weight (LBW), toxicity, and death [32].Common symptoms due to lead poisoning include abdominal pain, headache, fatigue, convulsions, nausea, difficulty sleeping, weight loss, anemia, difficulty concentrating, and loss of appetite [33].
Cadmium metal has a negative impact on humans.If humans consume plants whose soil is exposed to cadmium metal, the metal enters the body and circulates in the blood circulation and then accumulates in the organs, and then causes health problems [11].Cadmium metal has a high risk for liver and kidney health in humans [34].The process of entry of these heavy metals into the human body is through food and the absorption process.Cadmium which is absorbed through the digestive tract and accumulates in the liver and kidneys will cause heavy metal poisoning reactions [35].Exposure to Cadmium at high intensity can increase the risk of musculoskeletal diseases, such as rheumatoid arthritis, osteoporosis, and osteoarthritis [36].In addition, inhaling cadmium can also cause significant damage to the lungs, even to the point of death [37].Symptoms that indicate cadmium levels in the body exceed the threshold include irritation of the respiratory tract, nausea, vomiting, diarrhea, and stomach cramps [38].
Heavy metals such as lead, cadmium, mercury, copper, and strontium need attention because they are related to human health, agriculture, and ecotoxicology [39].Based on this, the community becomes more aware of heavy metal pollution by contributing their energy, thoughts, time, and funds devoted to planning, implementing, and supervising environmental preservation activities [40].

Recommendation
The number of negative impacts that can arise due to levels of heavy metals (Pb) and cadmium (Cd) that exceed the threshold in fresh cow's milk products requires several recommendations so that the existing impacts can be suppressed.So that public health and food supply can be maintained.To reduce lead and cadmium levels in cow's milk, effective and integrated efforts can be made to deal with this problem effectively.First, the selection of the location of the cattle farm needs to be considered.This is because human activities in various sectors can cause environmental pollution, including heavy metals such as lead and cadmium.Human activities such as the use of motorized vehicles can emit air pollution in the form of lead which can contaminate the surrounding environment [18].If lead air pollution reaches livestock areas, it will cause contamination of livestock.Therefore, it is important for cattle breeders and milk producers to choose farm areas that are safe from heavy metal contamination.
Cattle feed also needs attention to the threat of lead and cadmium contamination.The continuous use of inorganic fertilizers and synthetic pesticides can increase the content of heavy metals such as cadmium in the soil.So that animal feed that grows on the land can also be contaminated with cadmium [41].Thus, cattle that consume this feed have a high risk of being exposed to heavy metals which will affect the milk they produce.Therefore, dairy farmers and producers should adopt more environmentally friendly agricultural practices to avoid using fertilizers or pesticides that contain heavy metals.In addition, strict supervision of the feed used in cattle breeding is also important to ensure that there is no heavy metal contamination.For example, do not feed cows with kitchen waste or other human-produced organic waste because they may contain higher levels of lead and cadmium.
On the other hand, the role of government and related agencies is needed.Stricter regulations related to monitoring the quality of cow's milk can be implemented and realized.Some of the implementations are routine testing to test the content of lead and cadmium in cow's milk at several breeders so as not to exceed the maximum permitted limit for these contaminants.If milk is found that exceeds a predetermined threshold, handling efforts can be made to the related cow's milk producer.In addition, cow's milk products can also be directly contaminated by heavy metals such as lead and cadmium during the packaging and distribution process.Therefore, it is important for producers of fresh cow's milk to ensure product safety.Product safety control requires a systematic standard and follows existing standards.It is hoped that producers can implement a quality assurance system based on food safety with system standards such as HACCP (Hazard Analysis and Critical Control Point) [8].The standard includes a model for routine maintenance and monitoring of the entire production process, starting from product collection in the form of milking cows to the distribution production process.This is all done so that the fresh cow's milk products produced are free from lead and cadmium contamination they are safe for consumption by the public.

Conclusions
The Boyolali fresh cow milk sample tested had a heavy metal lead (Pb) content of 96.67 mg/kg, while a heavy metal cadmium (Cd) content was 4.45 mg/kg.Based on these results, both lead (Pb) and cadmium (Cd) levels in Boyolali's fresh cow milk samples exceeded the quality standard thresholds based on SNI 3141.1:2011 and SNI 7387: 2009, namely 0.02 mg/kg.The large content of heavy metals lead (Pb) and cadmium (CD) in the sample is because the sample is a fresh product without pasteurization.Therefore, several recommendations are needed so that the levels of heavy metals lead (Pb) and cadmium (Cd) in Boyolali cow's milk do not exceed the existing quality standards, as well as the process of heavy metal contamination in cow's milk and the resulting impacts can also be suppressed.Some of these recommendations include selecting livestock feed and farm locations that are safe from heavy metal contamination.In addition, the role of the government, farmers, and production parties needs to be increased to ensure the safety of fresh cow's milk products from the milking stage to the distribution process.

Table 1 .
Pb Standard Series Calculation Results

Table 2 .
Cd Standard Series Calculation Result

Table 3 .
Calculation Results of Lead and Cadmium Levels