Although lab test results show lead level in mackerel is within safe level, overtime consumption can lead to mental and physical problems, expert warns.
What comes to mind when someone mentions Palembang? Besides the Ampera Bridge, you might also think of pempek.
Pempek (fish cake) is a delicacy from Palembang, South Sumatra. It can be made using a few types of fish. Mackerel (Scomberomorus commerson) is one, since its flavor is preferred.
“Making pempek using mackerel is more lemak (delicious). You can taste the fishiness,” said Rohaya, a housewife in Palembang.
Due to its fiber content, softness, and sticky nature, mackerel meat is preferred over other fish. Its bones are also easy to remove and the meat is white in color, suitable for combination with starch or sago flour. Mackerel is also rich in nutrients, such as protein and omega-3 fatty acids.
Other foods in Palembang such as crackers, model and tekwan (fishball and pempek soups) are also often made using mackerel.
“It’s possible to make pempek or model and tekwan using ground meat from other types of fish, but mackerel is cleaner, whiter, chewier and dlicious,” Rohaya explains.
Mackerel can be replaced by other types of fish, such as Asian knifefish (Chitala), snakehead (Channa striata), snapper, dory, and anchovy. However, some of these fish are difficult to find and endangered. But mackerel and snakehead are still widely sold in traditional Palembang markets.
Because it is popular and sought after, mackerel is expensive. Ground mackerel in Palembang is sold for between Rp120,000-Rp150,000/kilogram. Meanwhile, ground snakehead meat ranges from Rp90,000-Rp110,000/kilogram, and ground snapper is sold at Rp30,000-Rp40,000/kilogram.
However, the high price hasn’t stopped consumers from always looking for the “Original Mackerel” label when shopping for food souvenirs in Palembang City.
But, what if the popular mackerel is contaminated with lead?
Potential heavy metal contamination
The issue of lead (plumbum/Pb) contamination in mackerel fish surfaced in 2022 following a study that analyzed levels of mercury and lead in ground mackerel conducted Evada Outri Dianti.
Dianti — a biology student from Raden Intan State Islamic University in Lampung — found that mackerel meat sold in three traditional markets in Palembang was contaminated with lead.
The lead content found in the ground mackerel meat samples from the three traditional markets exceeded the National Standardization Agency (BSN) consumption threshold of 0.3 mg/kg.
The study found the lead content in ground mackerel meat in Soak Bato Market, 26 Ilir Market, and Bukit Kecil Market, ranged from 1.90 mg/kg-2.90 mg/kg.
Lead harms humans. If exposed to lead in excess, a person can experience damage to the kidneys and central nervous system which can eventually lead to death.
Most mackerel sold in the three markets is frozen and packed in plastic. The fish will be ground when purchased. Main consumers are housewives and food entrepreneurs, both small and large scale.
But there are also stalls that sell fresh mackerel, then they skin, cut, and grind them directly at the kiosk.
Deni (37) owns a mackerel kiosk in Cinde Market. He sells fresh mackerel caught from Bangka Belitung and Lampung provinces.
“We produce fresh mackerel every day, from Bangka and Lampung. It is then sent here and not frozen,” he said, Thursday (10/8/2023).
“Yes, you can see for yourself. We separate the bones and meat of the mackerel one by one, then they are freshly ground and packaged, so that’s why the price is much higher than other places.”
Meanwhile, Toni (40), the owner of a mackerel grinding kiosk at Soak Batu Market, admitted that he sells mackerel from the Java Sea, through a fish agent at Jakabaring Main Market.
“We don’t pick them up every day. Usually, we stock up to one ton once it comes in,” said Toni.
Toni’s customers are mostly households or small business owners with a price of Rp140,000/kilogram. Toni added that several pempek shops are also his customers.
To learn more, Ekuatorial collected samples of ground mackerel from 26 Ilir and Saok Bato markets – the same two markets where Dianti collected her samples — and Cinde Market. Samples were sent to the Palembang Health Laboratory Center.
The first sample was taken on August 10, 2023 from Cinde Market and 26 Ilir Market.
Laboratory test results showed that ground mackerel from both markets had heavy metal lead levels of 0.043 mg/kg.
The second sample was ground mackerel meat from Soak Bato Market taken on August 30, 2023. As a result, the product contained only 0.027 mg/kilogram of lead.
These figures meet BSN consumption threshold and are much smaller than the levels Dianti found during her study last year.
Sriwijaya University Fishery Product Technology Study Program lecturer, Rinto, explained that laboratory test results differ very reasonably. Because mackerel is not a fish that only dwells in one aquatic habitat. Mackerels migrate or move around.
Not only migrating around Indonesian waters, mackerel can also swim outside the archipelago. The migration pattern is influenced by seawater temperature or spawning season.
Rinto continued, that it is very possible that mackerel taken in the same area but at different times will have different levels of heavy metal.
“So for heavy metals in mackerel, it is very possible to vary,” he explained. “So, the mackerel caught by our fishermen may not be a fish that has long inhabited our waters,” said Rinto.
There are not many other studies related to mackerel contamination in Indonesia. One study conducted by the Bogor Agricultural Institute in April, June, and August 2013 gained considerable attention.
Researchers found that mackerel from the Kronjo and Cituis areas in Tangerang District, Banten, contained high levels of heavy metals, especially lead.
A threat to physical and mental health
Almost as many nutrients as tuna and salmon are found in a healthy mackerel, which has a high nutritional value. They are rich in vitamins A, C, B1, omega 3, fat, and glycogen, which are very beneficial for maintaining immunity, increasing intelligence, and improving energy.
Excessive consumption can lead to lead accumulation in consumers.
In the food chain, lead compounds that contaminate fish cannot disappear and can enter the human body, causing several diseases.
In a paper entitled “Toxicology of Hazardous Heavy Metals and Their Impact on Health” published in the Journal of Environmental Health in January 2006, it is explained that human exposure to lead-contaminated materials can cause organ disorders such as neurological disorders (nervous system), kidney function, reproductive system, and hemopoietic system.
Acute lead poisoning will cause physiological disorders and chronic poisoning in growing children will cause physical and mental disorders.
The threats of consuming mackerel meat contaminated with lead are not limited to Indonesia.
In a study conducted by Van Nam Thai et al (2021), published in the National Center for Biotechnology Information Pubmed, they found that mackerel fillets in a number of countries contained high levels of heavy metals, reaching 180.99 mg/kilogram. This is above the recommended threshold of 0.3 mg/kg.
Children in Malaysia and the Philippines are said to be most at risk of health problems based on estimates of non-carcinogenic risk levels if they consume mackerel fillets.
However, Rinto said there are ways to process mackerel to make it safer for consumption. Rinto added that processing ground mackerel meat into foods like pempek will reduce heavy metal levels compared to fresh consumption.
Pempek is usually made with a 50:50 ratio between meat and flour. “In addition, the manufacturing process, starting with washing and so on, allows the reduction of heavy metal levels,” said Rinto, also a food science graduate.
Rinto’s explanation is also supported by the results of a study released by the Korean Journal of Fisheries and Aquatic Sciences of Gyeongsang National University in 2012. Cooking mackerel, according to the research team, will change the nutritional components in the mackerel and reduce heavy metal levels in the meat.
However, it is not only the mackerel meat that needs to be considered in the production process. The equipment and water used must also be free of heavy metal contamination.
Rinto said that currently, the sources of heavy metal contaminants are very diverse, such as air pollution and the use of contaminated water pipes. Lead contamination is difficult to detect since it will not change the smell, taste, and color of the mackerel.
Mackerel distribution in Indonesia
The mackerel sold in Palembang City is not cultivated locally, but imported directly from various regions in Indonesia.
“Based on the information from the fish distributor warehouse here (Palembang City), this mackerel is usually shipped from Java or Bangka,” said Junias Tarigan, the marketing section head of the South Sumatra fisheries office, when we met him on Monday (31/7/2023).
Junias also emphasized that mackerel sold in Palembang did not come from Tangerang waters. “Maybe the warehouse is in Tangerang and Bekasi, but not from Tangerang waters,” he said.
The types of mackerel most commonly found in Palembang markets are Indo-Pacific king mackerel (Scomberomorus guttatus) and streaked Spanish mackerel (Scomberomorus lineolatus). Spanish mackerel is often called super-category mackerel by traders.
Tarigan said mackerel shipment to Palembang is normally done three times per week with a total of 12 tons. The fish are then distributed to agents, traders, and micro, small, and medium enterprises (MSMEs).
Spanish mackerel groups live scattered in the oceans of the Western Pacific region. They range from North Africa, the Red Sea, Indonesia, Australia, Fiji, to China and Japan.
In Indonesia, mackerel groups are found in waters from Java to Papua. This is because this fish thrives in the tropics.
Data from the Ministry of Maritime Affairs and Fisheries (KKP) shows that mackerel production in Indonesia reached 203,759 tons in 2021. This number decreased by 2.81 percent compared to 209,654 tons in 2020.
With 38,990.47 tons produced in 2021, West Java produced the most mackerel. This amount is equivalent to 19.14 percent of national mackerel production.
Riau Islands Province is in second place with 16,293.58 tons, followed by North Sumatra at 11,789.95 tons.
Mackerel production in Indonesia fluctuates every year. Since 2010, the highest mackerel production occurred in 2017 when it reached 300,690.76 tons.
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