Testing water quality is an arduous task, especially in low-income regions. But that may change with an innovative approach of a "pregnancy test" for water.
The new testing method for water quality was developed by scientists at Northwestern University, a private research university in the US. Their method featured similarities with a typical pregnancy test, in which the handheld platform could test a water sample and determine the presence of a contaminant. The device would show either a positive or negative result. The determination of contaminants was derived based on the standards of the Environmental Protection Agency (EPA). They published their findings in the journal Nature Biotechnology.
The Estimated Populations with Access to Usable Water
Water is a crucial resource for humans, animals, and plants. People utilize it for drinking purposes, cooking meals, and irrigating farmlands. Without clean water, human communities will suffer severely from major consequences, including the collapse of numerous commercial and industrial sectors. Nowadays, water is used to generate power through hydroelectric technologies. So, nations need to put lots of efforts to conserve freshwater.
According to Statista, a German portal for statistics, the access of human populations to usable water improved throughout the years. In 1990, about 76% of the population had access to improved water sources while 24% could not. In 2000, around 83% of the population had access to improved water sources, which decreased the population without access to 17%. By 2017, approximately 93% of the world's population had access to improved water sources, leaving only 7% requiring the same access. Improved water sources indicate sources protected from outside contamination including fecal matter. But some of these sources might not be in optimal status. Thus, improved water sources do not represent safe, drinking water.
Meanwhile, the proportion of the world's population in urban and rural areas with access to water in 2017 varied, in terms of sources. Around 86% of the population in urban areas and 53% in rural areas had access to safely managed sources, while 11% of the population in urban areas and 28% of rural areas had access to basic sources. Although small in proportion, around 1% of the population in urban areas and 4% in rural areas could only access limited water sources. Data from reports also highlighted the 2% of the population in urban areas and 11% in rural areas supplied by unimproved sources. Despite advancements in water management, about 4% of the population in rural areas still depend on surface water.
A Pregnancy Test for Water
At Northwestern University, a team of scientists developed a new kind of testing method for water quality. Their method involves a handheld platform capable of testing one sample for contaminants. If the sample exceeded the standards of the EPA, it would flash a positive test result, meaning, one contaminant at an alarming level was found in the sample. The source of that sample could be contaminated with toxic chemicals or metals.
"Current water tests rely on a centralized laboratory that contains really expensive equipment and requires expertise to operate. Sending in a sample can cost up to $150 and take several weeks to get results. We're offering a technology that enables anyone to directly test their own water and know if they have contamination within minutes. It's so simple to use that we can put it into the hands of the people who need it most," said Julius Lucks, the lead author of the study and professor of chemical and biological engineering at Northwestern.
In the study, the novel method could address a major problem in testing water quality: the lack of taste buds. Since people could not see or taste all contaminants in the water, they would easily be prone to acute or chronic exposure to contaminants. To mimic taste buds, scientists utilized molecular machinery consisted of tiny parts in bacterial cells, such as DNA, RNA, and proteins. These tiny cellular parts were modified to perform a whole new set of tasks, different from their original functions.
Repurposing those cellular parts was possible because bacteria could taste things in the water naturally. Scientists simply had to make the bacteria work as detectors of whatever they could taste. With cell-free synthetic biology, they extracted the cellular parts that detect chemicals or substances in the water. Next, the parts were transferred into a test tube. Inside the test tube, the parts were rewired to provide a visual signal. The signal would be enough to alert a person if a test sample is contaminated or not.
To make the repurposed molecular taste buds practical for a wide range of applications, scientists freeze-dried them to significantly increase shelf life. If a user would want to test a sample, they need to put the freeze-dried pellet in a test tube and add a drop of water. Then, they have to flick the test tube to cause a chemical reaction. A glow from the chemical reaction indicates the presence of a contaminant.
The novel testing method named ROSALIND, which stands for RNA output sensors activated by ligand induction, was tested in Paradise, California. The location was recently razed by huge wildfires that burned almost 19,000 buildings, which resulted in the massive displacement of residents. The team utilized both ROSALIND and gold-standard tests for water quality. Results showed that gold-standard tests and ROSALIND detected the presence of toxic metals in the water supply.
However, between the two testing methods, ROSALIND could provide faster results at a cheaper price. The early version of ROSALIND could detect 17 various contaminants and toxic metals including copper, lead, cosmetics, and cleaning products. Because of promising results, a startup company made plans to commercialize the platform.
Testing water quality is particularly troublesome for residents. Those who transferred to a new residence may want to know if the water from their pipelines is safe to drink. Yet sending a sample and waiting for the test results are both expensive and time-consuming. It can take weeks before a credited laboratory sends out its feedback. But easy-to-use, portable test kits can allow residents to perform tests at home. The same kits can even enable residential areas to participate in water quality studies.