TRACE METAL CONTAMINATION OF DRINKING WATER IN EAST AFRICA, SIMILARITIES WITH THE CALIFORNIA CENTRAL VALLEY AND SAN DIEGO

As of 2016 the Centers for Disease Control has reported that 2.5 billion people in the world lack access to safe drinking water. From Mbarara, Uganda, to Flint, Michigan, drinking water contamination is a problem that can affect all nations. In addition to biological hazards, contaminants are usually classified into organic and inorganic, which can cause a variety of health risks. This work focuses on inorganic trace metal contamination in water from Nairobi, Kenya, San Diego, California, and the Central Valley of California, specifically a comparison of drinking water sources and treatment infrastructure.

There are many factors that contribute to inorganic contamination of drinking water. Contamination can occur in the source, through weathering of nearby materials, or it can be from anthropogenic processes such as farming and waste disposal, or dissolution of plumbing. Although contamination can be an issue, proper treatment infrastructure can be important. This was seen in the Flint Michigan’s water crisis, where the water was drinkable when leaving the treatment facility, but dissolved scale and plumbing once in the distribution system, leading to Pb contamination.

The Union College Water Initiative (UCWI) has analyzed over 1000 water samples, mostly from the northeastern U.S., but with a new set of 114 samples from southern California. The samples will be analyzed by ICP-MS for Cu, Zn, Pb, Se, As, Cd, Sb, Bi, Rb, Sr, Ba, and U. Due to the rather similar climate in Kenya and southern California, inorganic contaminants may have similarities at the sources. However, due to better infrastructure in California, drinking water at the tap is expected to be higher in quality. For example, in a report by Njuguna (2017) on 28 sites along the Nairobi river, only 4 had acceptable drinking water quality according to US-EPA standards, and only 3 according to the WHO, specifically for Cr, Pb, Fe, and Mn. In a state sponsored report (Clark, 1998) on the California Central valley, high flow events and droughts both led to higher concentrations of Cu, Pb, Cr, Cd, and Zn in surface waters. In a 2019 Public Utilities report by the City of San Diego, there were “non-detectable” amounts of Pb, Al, As, Ba, and Se, with very small amounts of Cu and Cr, both below EPA limits. Our new data set, to be collected in the next few weeks, will be a test of these findings.