ORIGINAL PAPER Health risk assessment of trace elements in drinking water from Najran City, southwestern Saudi Arabia Mohammad Mokammel Haque 1 & Hussien Abdulrahman Al Attas 2 & Mutaz Ali Hassan 3 Received: 11 June 2015 /Accepted: 29 April 2016 /Published online: 21 May 2016 # Saudi Society for Geosciences 2016 Abstract The concentrations of 16 trace elements (Ag, Al, As, B, Ba, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Se, Ti, U,and Zn) in drinking water from Najran City, Saudi Arabia, were deter- mined by inductively coupled plasma-mass spectrometry (ICP-MS) and compared with local, regional, and internation- al guidelines. Water samples from 22 water treatment plants and 13 commercial bottled water brands were analyzed. Except for B and U, the trace element concentrations were below the permitted limits defined in SASO, GSO, and WHO drinking water quality guidelines. The B concentrations in three brands of bottled water were 533.19, 602.29, and 1471.96 μg/L, which were all higher than the GSO and SASO limit (500 μg/L). The U concentrations were higher than the SASO limits for drinking water in two samples; one in treatment plant (2.39 μg/L) and another in foreign bottled water (2.17 μg/L). The median As, Ba, Cu, Ni, U, and Zn concentrations were statistically significantly higher in the treatment plant water samples than those in the bottled water samples, and conversely, the B concentrations were higher in the bottled water samples. The Cd, Hg, and Ti concentrations were below the detection limits of ICP-MS in all of the water samples. Apart from few exceptions, trace element concentra- tions in drinking water of Najran City were all within limits permitted in the national, regional, and international drinking water quality guideline values. Keywords Trace elements . Drinking water . Risk assessment . Saudi Arabia Introduction Certain trace elements are needed by humans in minute quan- tities for adequate growth and development and to maintain proper physical functions. Some trace elements are essential to health, and these microminerals are present in enzymes, hor- mones, and cells. Inadequate and excessive intakes of some of these trace elements may cause contrasting effects on health. Trace elements can be categorized as (1) essential to human life (chromium, copper, iodine, molybdenum, selenium, and zinc), (2) probably essential (boron, manganese, nickel, sili- con, and vanadium), and (3) potentially toxic, some of which possibly have essential functions (aluminum, arsenic, cadmium, fluoride, lead, lithium, mercury, and tin) (WHO 1996). Water is the basis of all life, and it is essential for many vital functions within the body. The adult human body is composed of approximately 60 % fluid, which is mainly an aqueous solution of ions and other substances (Hall 2010). Human health is dependent on the quality and quantity of water that is drunk. Water is an important source of trace elements to humans, but it can be contaminated with infectious agents, toxic chemicals, and radiologically hazardous materials. Drinking water quality in Saudi Arabia has been assessed in a number of studies. Al-Saleh and Al-Doush (1998) mea- sured trace elements in drinking water from 101 households and in 21 samples of retail bottled water in Riyadh, Saudi Arabia, using inductively coupled plasma (ICP) spectrometry and found that the Cd, Fe, Hg, Ni, and Zn concentrations in * Mohammad Mokammel Haque drhaquemm@gmail.com 1 Department of Preventive Dental Sciences, College of Dentistry, Najran University, P.O Box 1988, Najran, Kingdom of Saudi Arabia 2 Department of Restorative Dental Sciences, College of Dentistry, Najran University, Najran, Saudi Arabia 3 Department of Oral and Maxillofacial Surgery and Diagnostic Sciences, College of Dentistry, Najran University, Najran, Saudi Arabia Arab J Geosci (2016) 9: 464 DOI 10.1007/s12517-016-2501-z