Vol.:(0123456789) 1 3 Bulletin of Environmental Contamination and Toxicology https://doi.org/10.1007/s00128-020-02921-x Human Health Risk Assessment of Heavy Metal Contamination in New Calabar River Emmanuel I. Uwah 1,2  · Ima B. Nwoke 1  · Edu J. Inam 1,2  · Iboroakam E. Udosen 3  · Essien D. Udosen 1,2 Received: 14 February 2020 / Accepted: 21 June 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020 Abstract Concentration and human health risks of heavy metals (Pb, Cu, Cr, Cd, As, Ni) in water, sediment, crab (Tympanotonus fuscatus) and periwinkle (Callinectes amnicola) were assayed in New Calabar River, Nigeria. Results revealed that con- centration (mg/L) of the metals in water in the two seasons studied, ranged from 1.1E-2 ± 1.0E-3…for Cd to 2.90 ± 0.03… for Cu. In sediment, the concentration (mg/kg) ranged from 1.1E-2 ± 1.0E-3…for As to 5.17 ± 0.04… for Ni. In biota, the concentration (mg/kg) ranged from 0.01…for As in crab to 19.22…for Cu also in crab. Estimated human health risk from the metals contamination due to consumption of biota gave each of HQ and HI as < 1, indicating no risk except at Agip’s sample location where HI was > 1. Estimated human health risk due to dermal absorption through swimming, indicated no risk as each of HQ and HI was < 1. These make the river unpolluted except at Agip’s sample location. Keywords Heavy metals · Concentration · Risk assessment · New calabar river · Nigeria Industrial and municipal wastes are indiscriminately dis- posed into surface water bodies in many developing coun- tries including those in Sub-Saharan Africa because of weak environmental regulations (Arukwe et al. 2012; Inam et al. 2019). Hazardous chemicals may become enriched and bio- magnified through the food chain, posing risks to aquatic organisms. In addition, when fish and other animals from such water are used for human consumption, periodic moni- toring is needed to protect the health of those who consumed such fish and animals (Inam et al. 2019). The common envi- ronmental contaminants include toxic heavy metals, radio- nuclide, endocrine disrupting chemicals, toxic gases, plant nutrients and various oxygen consuming wastes (Inam et al. 2015). The sources of these contaminants include agricul- tural chemicals such as fertilizers, pesticides, and herbicides, atmospheric emissions from industries and households, lea- chates from waste dumps, community sewage, treated and untreated industrial effluents (Horsfall and Spiff 2013). Envi- ronmental pollution which used to be a peculiar problem of industrialised countries is now the problem of developing countries because of weak enforcement of environmental pollution control laws and regulations (Oketola and Fagbe- migun 2013). Heavy metals are some of the major chemical pollutants that have lasting effects on the natural balance in aquatic sys- tem. They are serious environmental problems in the marine environment, and sediment is the ultimate sink of these con- taminants (Huang et al. 2009; Emara et al. 2015). These chemical pollutants are not biodegradable, so they can affect the environment adversely for a long time. Biodegradability means the ability for the pollutants to be removed from the environment through natural biological processes (Travizani et al. 2016). In the aquatic system, heavy metals tend to accumulate in the bottom sediment and become concen- trated by biota. The process of accumulation of heavy met- als by fish and aquatic animals through non dietary routes is called bioconcentration (Travizani et al. 2016). The toxicity of heavy metals can result in reduced mental and central nervous system functions, reduction in energy, damage to blood compositions, the lungs, kidneys, liver, and other vital organs (Onwali et al. 2014). There is every need to screen for these contaminants in aquatic environment in order to promote environmental protection. * Emmanuel I. Uwah emmanueliuwah@uniuyo.edu.ng 1 Department of Chemistry, University of Uyo, Uyo, Nigeria 2 International Centre for Energy and Environmental Sustainability Research (ICEESR), University of Uyo, Uyo, Nigeria 3 Department of Zoology, Akwa Ibom State University, Akwa Ibom State, Nigeria