CHROMIUM AND LEAD CONTAMINATION IN COMMERCIAL POULTRY FEEDS OF BANGLADESH

Heavy metals contamination into food chain is considered as an emerging crisis throughout the world especially in developing countries like Bangladesh. The concentration of heavy metals including Cr and Pb in commercial poultry feed samples (protein meal feed, meat and bone meal and fish meal feed) were detected by using Air/ Acetylene Flame Atomic Absorption Spectrophotometer. The mean concentration of heavy metals were found in protein meal feed in a range where Cr 10.63 to 218.10 mg kg-1 and Pb 7.37 to 52.25 mg kg-1. In meat and bone meal feed samples, Cr was recorded from 9.15 to 40.59 mg kg-1 and Pb 5.0 to 61.42 mg kg-1. Cr was found 17.68 to 78.39 mg kg-1 and Pb 3.54to 16.44 mg kg-1 in fish meal feed samples. However, results showed that all feed samples contained chromium and lead where both metals were present at alarming levels in most of the samples. It is therefore suggested that regular detection of heavy metals especially Cr and Pb should be done to evaluate the health risks and to protect the end user from food that might harmful for their health.


Introduction
The tanning industries of Hazaribagh, Bangladesh are manufacturing hide about 220 metric ton day -1 with the discharge of 600-1000 kg of solid waste/ton processed hide.The tannery solid wastes are used as poultry feed, fish feed, and in production of organic fertilizers by converting to protein-concentrate with some treatment.Recently numerous large and small mills are established to renovate proteinconcentrate (about 200-250 tons day -1 ) from tannery solid wastes.Heavy metal, particularly chromium (Cr), is one of the significant threats, utilized as a part of the tanning processes.In perspective of the actualities, chromium may immigrate to poultry items and besides biomagnifies into food chain (Hossain et al., 2009).
Through bioaccumulation heavy metals are responsible for producing some toxicity in human such as neurotoxicity, nephrotoxicity, fetotoxicity and teratogenicity which may led disturbance in blood, gastrointestinal, nervous systems and cardiovascular system, changes in the detoxification pathways (colon, kidney, liver, skin), release and functioning of various hormone.Because of heavy metal contamination, mental behaviour, neurological functions and utilization of neurotransmitter may be deviated in human body (Iftikhar et al., 2014).
Preliminary studies in different parts of the world indicate that poultry feeds are exposed to contamination by heavy metals and trace elements.Hossain et al. (2007) analyzed various types of solid tannery waste (used for proteinconcentrate production) for chromium, cadmium, lead, arsenic, and mercury contents in Bangladesh.The maximum chromium content of the solid waste was found to be 3.2%.Zhang et al. (2012) found that poultry feed had high concentrations of heavy metals in China.Similarly, high levels of heavy metals were found in poultry feed in Pakistan (Iftikhar et al., 2014).
However, there is invariably insignificant data in literature performed on heavy metal contamination in poultry feed available in the different markets of Bangladesh.Hence, the study is important to meet a void in research.The aim of this study was to assess the levels of chromium (Cr) and lead (Pb) concentration in selected poultry feed (Protein meal, meat and bone meal and fish meal) samples available in the different markets of Bangladesh.

Collection of poultry feed samples
Commercial poultry feed samples as protein feed, meat and bone meal and fish meal were collected from markets of different locations (each districts) in Bangladesh.
For analyzing the parameters, protein feed samples were coded as Brand PM1 to Brand PM10, meat and bone meal samples were coded as Brand MBM1 to Brand MBM12 and fish meal samples were coded as Brand FM1 to Brand FM7.

Preparation and analysis of feed specimens
A total of 290 commercial poultry feed samples including 10 brand of protein feed, 12 brand of meat and bone meal and 7 brand of fish meal along with 10 replicates each were purchased from different markets in Bangladesh.Samples were prepared by wet digestion method as described by AOAC (2005).2g of feed was digested by 10ml M HNO3 for 24 hrs, then heated at 200ºC for 15-20 minutes and cooled 5 to 10 minutes, after that added 10 ml of Aqua regia (HNO3: HCl, 3:1), reheated to ensure dryness and cooled for 5 to 10 minutes.Then diluted with 100 ml of distilled water, filtered through Whatman filter paper No. 42 and finally stored in volumetric flask.The required volume (100 ml) of the filtrate was used to measure heavy metal levels in feed samples by using Air/ Acetylene Flame Atomic Absorption Spectrophotometer (Analytikjena, ZEEnit Model: 300P, Germany).At each step of digestion processes, acid blanks (laboratory blank) were prepared in order to ensure that the samples and chemicals used were not contaminated.They were analyzed by atomic absorption spectrophotometer before the samples and their values were subtracted to ensure that the equipment read only the exact values of heavy metals.Each set of digestion has its own acid blank and was corrected by using its blank.Each standard solution was measured 3 times and the mean were plotted.A blank solution of distilled water was used to check accuracy of the standard solutions and it was run after every 10 samples.The absorption wave lengths for the heavy metals were 357.87 nm for Cr and 217.0 nm for Pb.

Statistical analysis
The data that were obtained from the experiments were statistically analyzed to find the mean and standard deviation among the various samples in triplicate.Data were analyzed using the software, IBM SPSS Statistics, version 20 at the 0.05 level.

Cr and Pb content in Protein meal feed samples
The mean concentration and associated standard deviation of Cr and Pb in commercial protein feed meal samples are presented in Table 1.The mean concentrations were found in commercial protein feed meal samples in the range as Cr 10.63±1.52 to 218.1±2.54 mg kg -1 and Pb 7.37±0.48 to 52.25±0.97mg kg -1 .

Cr and Pb content in meat and bone meal feed samples
The mean concentrations and associated standard deviations of Cr and Pb in meat and bone meal feed samples are presented in The level of Pb was detected highest in Brand MBM1 (61.42±0.38 mg kg -1 ) and lowest in Brand MBM4 (5.0±1.4 mg kg -1 ).According to the EU (2003) maximum permissible concentration for Pb is 5 mg kg -1 in feed.In this study, about 92% meat and bone meal feed samples had excess amount of Pb whereas acceptable limit is 5.0 mg kg -1 for feed according to EU standard.Usually 4.362 mg L -1 lead could be existed in the effluent from tanneries (Tariq, 2009) which might be a source of Pb contamination in meat and bone feed meal samples.

Cr and Pb content in Fish feed meal samples
The mean concentrations of Cr and Pb in commercial fish feed meal samples are presented in Table 3.In fish feed meal samples, the mean concentration of Cr was recorded as 17.68 to 78.39 mg kg -1 and Pb 3.54 to 16.44 mg kg -1 .
Cr content in Brand FM7 (78.39 mg kg -1 ) were higher and in Brand FM3 and Brand FM5 (17.68 mg kg -1 ) were lower in fish feed meal samples.Chromium was detected from all fish feed meal samples.There is no maximum allowed concentrations of chromium for feed ingredients and compound feed in EU ( 2003) regulations.
The highest Pb content was found 16.44 mg kg -1 in Brand FM6 while the lowest value was found 3.54 mg kg -1 in Brand FM4.It was found that mean concentrations of Pb from all commercial fish feed meal samples were 14% below, 29% optimum and 57% higher than the maximum permitted concentrations (5.0 mg kg -1 ) recommended by EU (2003).Lead toxicity is known to cause musculo-skeletal, renal, ocular, neurological, immunological, reproductive and developmental effects (Ambedkar and Muniyan, 2012).

Conclusion
Now-a-days, heavy metal contamination is predominant throughout the Bangladesh and hence presented as an alarming level in poultry feed.Cr and Pb concentrations in poultry feeds are important to know in order to regulate the consumption of poultry products.The present study showed that all feed samples contained chromium and lead.However, Chromium concentration is higher in protein meal feed and lead concentration is higher in meat and bone meal samples than other feed samples.The current regulations do not permit chromium in poultry feed.The average chromium content in all feed samples was several times higher than allowed chromium concentrations for human foods.More detailed research is needed for investigation of six-valent chromium and it's potential hazards in animal and human.Lead was higher for maximum studied commercial poultry feed samples than those specified EU (2003) in 5.0 mg kg -1 .It is therefore suggested that regular survey of heavy metals especially Cr and Pb should be done to evaluate health risks and to find possible protective measures to avoid the health injuries.

Table 1 .
Concentration of Cr and Pb in Protein feed meal samples.

Table 2 .
The mean concentrations of heavy metals were found in all meat and bone feed meal samples in the range as Cr 9.15±1.29 to 40.59±1.54mg kg -1 and Pb 5.0±1.4 to 61.42±0.38 mg kg -1 .

Table 2 .
Cr and Pb concentration in Meat and bone feed meal samples

Table 3 .
Concentration of Cr and Pb in fish feed meal samples.