Determination of levels of lead and cadmium in various meat tissues of beef, goat and lamb

Abstract

Meat is widely considered an important source of protein, vitamins and minerals such as selenium, iron, zinc, vitamin B. Besides consumption of meat muscle tissues, it is known that in the Mediterranean area certain populations also consume other meat tissues such as the bone marrow fats, and what is known as ''Fashi'' or ''Ma'alak'' which contains the kidneys, spleen, liver, heart and lungs. In addition, muscle, liver and kidney tissues of such organisms are mostly consumed raw, without any further processing. The hazard arises from the fact that such meat products are gained from organisms which in turn have accumulated toxic metals in their tissues. Therefore, levels of lead (Pb) and cadmium (Cd) from different fresh meat tissues of beef, goat and lamb were determined in Lebanon for the first time. Their inter- and intra-levels of distribution were estimated and compared. Their possibility exposure risk from dietary intake was also studied. A total of two hundred and forty (n=240) samples of fresh meat tissues (n=80 beef, n=80 goat and n=80 lamb) were collected over a period of several months from different slaughter houses. Each individual sample was then subdivided into subsamples for subsequent analysis and quality control purposes. Highpressure closed vessel acid-assisted microwave digestion was used to digest all samples, while graphite furnace atomic absorption spectroscopy was used for the quantification of the toxic metals. The data showed that the mean levels of Pb in goats ranged from 2.66 to 69.84 µg/kg for the different tissues studied. In beef, they ranged from 0.50 to 41.34 µg/kg. While in lamb, levels ranged from 1.59 to 95.95 µg/kg. Meanwhile, the levels for Cd ranged from 2.39 to 635.86 µg/kg for goat, 0.55 to 173.72 µg/kg for beef, and 1.37 to 688.95 µg/kg for lamb. Based on the inter-level distribution of lead and cadmium in various tissues, beef meat tissues were found to have lower levels than lamb or goats. These findings suggest that consuming beef meat tissues is much safer due to less exposure to such metals. For the intralevel distribution of lead in goats, the spleen, kidney and liver were found to have the highest levels. The same type was also found for beef and lamb. As for cadmium, the data was clear in showing that in all three types of organisms and within each of their tissues, the liver and the kidneys accumulated noticeably high amounts as opposed to their other tissues. In comparison to the maximum allowable levels (MAL) for Pb and Cd in meat (100 and 50 µg/kg, respectively), none of the samples have exceeded the MAL for Pb, whereas for cadmium, the liver and kidneys from all three organisms have exceeded the MAL for cadmium. According to provisional tolerable weekly intake levels (PTWI) for lead, and assuming a weekly consumption of 1 kg of the most contaminated meat tissue (lamb liver, 95.95 µg/kg) by a 60 kg individual, 6.4% of the PTWI will be reached. For a 14-year old child however, 27.4% of the PTWI will be reached suggesting that in the case of lead, no major health concerns are present. For cadmium however, and considering the most contaminated tissue (lamb kidney, 688.95 µg/kg) 164% of Cd's PTWI will be reached by a 60 kg individual. The matter is much worse for a 14-year old child where 703% of the PTWI will be reached. In general, the work shows that beef tissues are safer for consumption but nevertheless, tissues from liver and kidneys of goat, beef and lamb should be minimized in all cases especially for children.