Heavy metal residues in cow milk: BAU study finds

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Kafi Khan, Mymensingh :
Bangladesh Agricultural University scientists have found the presence of heavy metal residues in cow milk. The findings of their six-month study which ended December 2016 and published by the Bangladesh Journal of Animal Science said researcher Shakhwat Hossain, a PhD student at the animal science department of Bangladesh Agricultural University, Mymensingh. During the study, said Shakawat Hossain that he and his supervisor (Professor Dr. Md. Abul Kalam Azad) found lead, zinc and cadmium residues in cow milk in concentrations which are considered to be toxic for human health by the World Health Organization. He said that the presence of lead residue in the milk samples was found to be twice the approved limit. The presence of cadmium and zinc residues was found to be three and eight times higher than the permissible levels, said Shakhawat Hossain. Garbage waste, feces and milk content heavy metals to a major extent. Heavy metals in milk came from that contaminated garbage waste, said Shakhawat Hossain. Municipal garbage waste contains higher amount of heavy metals and increases health and environmental hazards. Garbage wastes use as animal feed to fate in products level, in dairy cattle roaming freely and roaming cattle were daily consumed garbage wastes which possessed heavy metals such as Pb, Cd, and Zn to a major extent, resulting in introduction of trace elements in the human food chain. About 2% of the total livestock are available in urban and peri-urban areas of Bangladesh said Shakhawat Hossain. Interestingly, urban livestock production system is operating unplanned and densely populated neighborhoods which has negative impact on public health and also introduces environmental pollutions. Local political leader is kept the highest number of animals in municipal areas whereas self-employer or trader takes the second position. Dairy cattle share a lion number (67%) over other species. More than 75% livestock holders keep their animals over 3 years and only 6% keepers sell their animals within 6 months. Most of the livestock keepers (56%) use their calf as replacement stock. The majority (66%) of the livestock depends on grazing and scavenging for feed from government and municipal lands, unfenced open land, roadsides, rubbish dumps. Most of the livestock owner does not supplement to their animals with feeds other than free scavenging throughout the rearing time. Most of the roaming cattle in municipal areas eat mixed form of wastes such as food and kitchen leftover, green waste, papers, paints, chemicals, fertilizer, pesticides, herbicides, tannery wastes and medical wastes. All types of municipal waste contain heavy metals and roaming cattle in urban areas are usually taken those wastes said, Shakhawat Hossain. Dung and urine disposal in public places, malodour and road blockages are other problems created by livestock rearing in urban areas. The problem is aggravated by unmanaged fodder and shelter for the livestock. It is shown that 86% of the livestock were kept in temporal sheds. They also showed that two thirds of the total livestock reared in the urban areas roamed freely on the roadside and fed on garbage, and 79% drank water from drainage lines. The pathogens, heavy metals and other chemicals consumed by the animals pass to humans in the food chain through dairy and meat products, said Shakhawat Hossain.
Most (68%) of the livestock reared in the study area are reared for dairy purposes, while 24% were reared for beef. Despite the grave risk to public health and environment, little effort has been made to curb the situation.
The law is silent on the issue and there is no database or estimation of how many cattle are reared in the urban areas. There is no regulation related to banning livestock in urban areas. Moreover, it’s mostly the politicians and the “musclemen” that keep the livestock. So nobody can raise a finger against them. Indeed, the research findings show that 58% of the livestock keepers were politicians and 26% were self-employed traders, both powerful sections of the society. That could be the reason why no precautions or care is taken in rearing livestock in a managed way in order to reduce the adverse impact, although most livestock owners had basic education and all of them were aware of the negative impacts of livestock rearing in urban areas. The research showed that 100% of the participants were aware of the adverse effects that livestock rearing would have on public health and environment and 73% had at least primary education. Serious steps need to be taken to bring this situation under control as it could invite uncontrollable epidemics if it goes unchecked said Shakhawat Hossain according to Bangladesh Journal of Animal Science.
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