Potential Human Health Risks of Tannery Waste-contaminated Poultry Feed

For over a decade, solid tannery waste has been converted into protein concentrate and used as a feed ingredient because of its cheap availability. However, as chromium sulfate is commonly used in the tanning process, the chromium (Cr) content of tanned skin-cut wastes (SCW) may enter the edible parts of poultry through feed. Therefore, there is a chance that Cr and other heavy metals may be present in the edible portion of poultry and consequently transfer to humans upon poultry consumption.

In this study, skin-cut wastes (SCW)-based poultry feed and the edible parts of chicken fed with this feed were analyzed to understand the potential health risks of their use as poultry feed.

In the present study, the presence of heavy metal content in SCW, poultry feed, and edible portions of different kinds of chicken was determined using atomic absorption spectrophotometer methods and the associated health risk estimation was calculated by comparing the target hazard quotient (THQ) value and reference daily intake value.

The results revealed the presence of Cr content ranging from 0.12-3.11 mg/kg and lead (Pb) content ranging from 8.06-22.0 mg/kg in SCW. In addition, Cr and Pb were present in the range of 0.27-0.98 mg/kg and 10.27-10.36 mg/kg, respectively, in poultry feed. However, no cadmium (Cd) was found in SCW, but the presence of Cd ranged from 0.03-0.05 mg/kg in feed. When contaminated poultry feed was fed to live poultry, the presence of Cr, Pb and Cd was observed in the edible portions (i. e. skin, liver, gizzard, and meat). Irrespective of the edible parts and chicken type, Cr values ranged from 0.1-2.440 mg/kg; Pb values ranged from 0.257-1.750 mg/kg; and Cd values ranged from below detection limit (BDL) to 0.037 mg/kg.

The estimated daily intake value, THQ, along with the aggregate hazard index value, indicated a potential risk to consumers through consumption of contaminated chicken. Therefore, the study results clearly demonstrate heavy metals accumulation in chicken due to feeding SCW-based feed. The contaminated chicken further transfers these heavy metals to humans through ingestion. Hence, there is a potential human health risk through consumption of contaminated chicken meat.