Association between the concentration of nitrate and phosphate ions in drinking water and the occurrence of goiter in Nandi Hills, Kenya

Abstract

Nitrates and phosphates are among the major inorganic pollutants in the environment, primarily contributed by nitrogenous and phosphate fertilizers, organic manures, human and animal wastes, and industrial effluents through biochemical activities of microorganisms. Beside other known detrimental effects, research findings suggest that increased nitrate and/or phosphate intake affects the functioning of the thyroid gland in humans. In Kenya, goiter remains endemic despite iodization of table salt in households. Notably, the area around Nandi hills in Nandi County has recorded high incidences of goiter in the recent past. This indicates that factors such as inorganic ion content of water (among others) may have etiological role in endemic goiter cases in the region. This study sought to determine the etiological factors leading to observed high prevalence of goiter. Both nitrate and phosphate levels in stream and borehole water were found to be within the WHO acceptable limits. Pearson Correlation results reported an insignificant positive association (P>0.05; r>0) between nitrate-phosphate-iodine ions and occurrence of goiter in the study. The study therefore concluded that concentrations of nitrate-phosphate ions and iodine levels in water and table salt respectively are not the main cause of goiter in the study area. This calls for additional studies to be carried out on other possible causes of goiter in the study area.