Correlation between exposure to toxic heavy metals in fish, sediment and drinking water, and high incidence of prostate enlargement in two states of the Niger-Delta, Nigeria

Abstract

We studied the correlation between the chronic environmental exposure to polyaromatic hydrocarbons (PAHs) and six toxic heavy metals in the Niger Delta and the incidence of prostate enlargements in men. The field research was conducted in three communities in two states viz: Ondo and Akwa Ibom. Prostate gland enlargement in men 40 years and above was determined by rectal examination in situ, while levels of PAHs and metals were obtained in drinking water from boreholes, surface water (river), hand dug-out wells, rain water, sediment; and in five species of locally consumed fish by Gas chromatography (GC) and Flame Atomic Absorption spectrophotometry (FAAS), respectively. Results show high incidence rates of prostate enlargement in the two states: Ondo (combined rates of Igbokoda and Ilepete communities) at 39.4% and Akwa Ibom (Ibeno Community) at 33.3%. Both rates are much higher than those of World Health Organization world–wide (WHO) rates and the African rates of 14% and 11 to 12%, respectively, representing 178.5%/227.3% and 135.7%/175% increases, respectively. Correspondingly, levels of the six heavy metals (Ni, Cr, Cd, Pb, Mn and Co), were excessively high in fish and sediment samples in Ondo and in drinking water and sediment in Akwa Ibom, all surpassing WHO maximum permissible levels over 10-fold. However, PAH levels in all samples at the three locations in the two States were near absent. These results clearly suggest an exposure–response relationship, to the heavy metals as all volunteers who are domiciled in the communities for over twenty years, are primarily shallow-water fishermen and consume the fish they catch. Also, they all denied any close relative, dead or alive, with the disease. Without prejudice to genetic and/or lifestyle pre-disposition therefore, it is our conclusion that the six heavy metals may be implicated as causative agents maybe in synergy with “other” factors, in inducing the extremely high incidence rates of prostate enlargement we observed in the three communities of the two states of the Niger Delta.

Keywords: Toxic heavy metals, exposure, incidence, prostate enlargement, Niger-Delta.