Having good water quality is something that is important for both human and ecological health. In order to have good water quality, there needs to be a lack of impurities in the water such as heavy metals, unbalanced pH, and other substances that could make their way into a water source. The cleaner the water is, the more likely that surrounding populations will thrive. There are several heavy metals that make their way into water systems that can be damaging to people and the environment. Two of these heavy metals include iron (Fe) and lead (Pb). Iron is a necessary nutrient in the body for transporting oxygen in the blood and for metabolism. However, iron in water systems can be detrimental to health, as an excess can lead to the growth of bacteria in the gut and can damage several organs including the pancreas and the liver in most mammals (1). Iron naturally exists in the environment in water reservoirs, but it has also been introduced from industrial wastes, refining of iron ores, and corrosion of iron containing metals from infrastructure.
According to the CDC, there is no safe level of lead for humans, and therefore any trace amounts of lead in water can be extremely damaging. Lead is a neurotoxin and can result in damage of the kidneys, blood, and nervous system or coma and death (2). All vertebrates, not just humans, are also largely impacted by lead in the reproductive, gastrointestinal, cardiovascular, nervous system, musculoskeletal, and renal systems. During the 20th century, and peaking in the 1970s, lead was used in many products, especially in industrial areas. Lead was put in paint, pipes, batteries, cosmetics and more, many of which have been banned once the toxicity was identified. One of the current sources of contact that is still very common is from lead paint that was just painted over, and therefore is still present in homes and public buildings. Children are especially susceptible to lead exposure from lead paints due to constantly touching walls and floors when crawling around. They stick their hands in their mouths, swallowing chipped pieces of lead paint (6). As lead paint chips and falls onto the ground, specifically from painting the outsides of buildings or playgrounds, this allows for trace amounts of lead in the soil, allowing for easy transport to groundwater and other water reservoirs (3).
One of the most infamous examples of lead poisoning in the US is in Flint, Michigan, which began in 2014 and is ongoing. There was a switch in the source of water that was being used in the town from the municipal water supply to the Flint River, and this water happened to be much more corrosive. This became an issue because the water was being transported through lead pipes. As the water passed through the pipes to homes and other infrastructure, the lead followed suit. The lead in the water also increased ideal conditions for other bacteria to grow. This switch prompted many reports of funny smelling and tasting water, skin rashes, hair loss, increased blood lead levels in children, and a deadly outbreak of Legionnaires’ disease (a bacterial disease similar to pneumonia)(4).
One way to manage these sorts of issues is to regularly monitor the water quality and potential presence of toxins in water sources. By constantly testing water to identify potential issues, there is the ability to catch a potential issue before it becomes as major as the Flint Water Crisis. One way to test for these heavy metals is through colorimetry, which is used to identify the certain concentrations of materials in a solution. By running different wavelengths of light (Figure 1.) through a sample and seeing which colors of light are absorbed and how much of the light is absorbed. This is matched to pre existing standards to identify potential toxins in water and their concentrations. It is important to then compare the concentrations that are detected to different policies and “safe” levels. If the concentrations are above legal limits, action should be taken to address the situation in order to ensure the safety of the people and the environment that interacts with the water source. More information regarding legal levels of metals in water can be found here (5).