In 2016, unknowing officials threw the residents of Flint, Michigan into turmoil, when scientists discovered their drinking water supplies contained unhealthy levels of lead.
Officials, in 2014, changed the drinking water source for the city from Lake Huron and the Detroit River to the cheaper Flint River. Lead leached from the lead water pipes into the drinking water, due to insufficient water treatment, exposing over 100,000 residents.
Federal officials declared a state of emergency in Jan. 2016. They told Flint residents to use only bottled or filtered water for drinking, cooking, cleaning, and bathing.
The water quality had returned to acceptable levels as of early 2017. All the lead pipes are being replaced, which is expected to be completed no sooner than 2019.
Lead exposure can come from ingestion of lead in paint, dust, soil, air, and food, as well as drinking water, according to the U.S. Environmental Protection Agency.
Lead at any levels can affect health. The EPA and the Centers for Disease Control and Prevention agree that there is no known safe level of lead in a child's blood. Even low levels of lead in the blood of children can result in behavior and learning problems, lower IQ and hyperactivity, slowed growth, hearing problems, and anemia.
Pregnant women are at particular risk. Lead can accumulate in our bodies over time, where it is stored in bones along with calcium. During pregnancy, a woman’s bones release lead as the body uses maternal calcium to help form the bones of the fetus. Serious effects include reduced growth of the fetus and premature births.
Adults can suffer from cardiovascular effects, increased blood pressure and hypertension; decreased kidney function; and reproductive problems in both men and women.
Lead can enter drinking water from corroding service pipes that contain lead. This is particularly worrisome where the water has high acidity or low mineral content and corrodes pipes and fixtures, according to the EPA. The most common problem is with brass or chrome-plated brass faucets and fixtures with lead solder. Significant amounts of lead can enter into the water, especially hot water.
Homes built before 1986 are more likely to have lead pipes, fixtures, and solder.
Scientists are using a complex spectrographic method to detect lead contents and other elements in water. It is called inductively coupled plasma optical emission spectrometry, or ICP-OES. Scientists use this analytical technique to detect chemical elements, and is one of the most powerful and popular analytical tools for determining trace elements in numerous sample types.
Elemental analysis of water is one of the major applications for Inductively Coupled Plasma – Atomic Emission Spectrometry. It is capable of measuring up to 70 elements of the periodic table, and that with its tolerance to difficult matrices makes it the ideal tool for the analysis of many different types of water. Those include drinking water, surface water, wastewater, sewage, and seawater, according to Matthieu Chausseau, Ph.D. and Elemental Analysis & Thin Films Product Manager for HORIBA Scientific.
Samples of water are usually sent to the laboratory after sampling on the field. It requires the addition of a small amount of acid to make sure the samples are stable over time. Once received in the laboratory, researchers perform the analysis directly or, in some cases, sample preparation is required. Sample preparation usually consists of hot acid digestion and filtration of the sample prior to analysis.
The spectroscopy technique uses a complex series of actions, light and optics to detect the elements in the sample.
The ICP-OES analysis itself is fully automated. A peristaltic pump transports the sample to a nebulizer that mixes it with Argon gas to create an aerosol. A spray chamber filters the aerosol to send only the finest droplets to the plasma. The plasma, made of ionized Argon and sustained using a magnetic field, is a source of energy. The water sample is going through different steps: desolvation, vaporization of particles, dissociation, atomization of molecules and even ionization and excitation of ions. When excited atoms and ions return to a lower energy state, the instrument collects emitted light into the optics. Each wavelength is characteristic of one, and only one, element. Its intensity is proportional to the concentration in the sample. Using calibration curves, the ICP-OES system can provide the concentration for all the elements of interest in minutes.
Users of ICP-OES are mainly contract laboratories. States may have specific facilities to handle water analysis. Most of the time, a facility is dedicated to a group of municipalities or states.
Large municipalities may have their own laboratory (South San Francisco and San Diego as an example). Most of the time, they are not at the treatment plant or on the production plant premises. Engineers send samples to the contract laboratories for analysis.
Researchers monitor many elements during most ICP-OES analyses, not just lead.