International Journal of Sciences: Basic and Applied Research (IJSBAR) ISSN 2307-4531 (Print & Online) http://gssrr.org/index.php?journal=JournalOfBasicAndApplied -------------------------------------------------------------------------------------------------------------------------------------- Nitrate in Groundwater and Excretion of Nitrate and Nitrosamines in Urine: A Review Aida Soraya Shamsuddin a , Sharifah Norkhadijah Syed Ismail b* , Shaharuddin Mohd. Sham c , Emilia Zainal Abidin d a,b,c,d Department of Environmental and Occupational Health, Faculty of Medicine and Health Sciences, University Putra Malaysia (UPM), 43400 Serdang, Selangor, Malaysia b Email:norkhadijah@upm.edu.my Abstract Nitrate is harmful to humans as it can form endogenous nitrosamines which can cause cancer. The major contribution of nitrate contamination in well water is largely from agricultural activities (e.g.; fertilizers and pesticide), wastewater treatment plant discharge, animal yard and manure storage lagoons. Biomarkers such as urine and saliva can be used to determine the occurrence and formation of nitrosamines in the human body. This paper provides an overview of nitrate occurrence in groundwater and the mechanism of nitrosamines formation and its excretion from human body via urine and saliva. The suitability of urine and saliva as biomarkers of endogenous nitrosamines formation were also discussed in this review. Keywords: groundwater; nitrate; nitrosamines; urine; saliva 1. Introduction Humans have altered the nitrogen cycle dramatically over the last century, and as a result, nitrate (NO 3 - ) is steadily accumulating in water resources such as in groundwater and surface water. Contamination of NO 3 - in groundwater is a worldwide problem [1] and fertilizers are the largest contributor of anthropogenic NO 3 - worldwide. Other major sources include animal and human wastes, nitrogen oxides from utilities and automobiles, and leguminous crops that fix atmospheric nitrogen [2]. These organic and inorganic sources of nitrogen are transformed to NO 3 - from the mineralization, hydrolysis, and bacterial nitrification process [3]. ------------------------------------------------------------------------ * Corresponding author. E-mail address: norkhadijah@upm.edu.my. 176