By Charly SHELTON

Water is life. So the adage goes, which has been true through human history. Where the water flows is where humans would settle. Water is needed to live. Good, clean water. But, generally, the quality of tap water found in modern homes can be spotty, especially in Southern California where water has to be imported to ensure reliable service. During the import process, water can pick up contaminants along the way.

Luckily, the Crescenta Valley has a well beneath the bedrock to draw from but that has its own set of contaminants from rain runoff leaching into the well. Suffice it to say, pure water is not always pure.

The state sets up standards – Maximum Contaminant Levels or MCLs – that ordain what is a safe level of each contaminant. For instance, less than one part per million of aluminum is considered safe. Less than 10 parts per billion of arsenic is considered safe. Less than 300 parts per billion of iron is considered safe. As long as the water tests lower than the max allowed for each contaminant, it is considered safe drinking water. But Dr. Tasha Stoiber and her team of scientists at the Environmental Working Group want to revise the definition of what is considered “safe.”

“What we wanted to do was look at a cumulative assessment of multiple co-occurrent contaminants in the state’s drinking water. Right now the way that contaminants are assessed and regulated is one at a time; we wanted to calculate a cumulative risk assessment,” Stoiber said. “We looked at one in 1 million cancer risk levels and we also looked at additive cancer risk. What would be the cancer risk of multiple co-occurrent carcinogens that might be in a community water system that someone is exposed to?”

Basically, if drinking water has 299 ppb iron and that’s it, the body could process and handle it no problem. And the current drinking water standards reflect that. But when water has 299 ppb iron and 0.9 ppm aluminum and 9 ppb arsenic all at once, it adds up to be considered unsafe.

The problem lies in the standards that weigh each contaminant individually for safe levels rather than considering contaminants overall as a whole. The study published by Stoiber’s team espouses the importance of assessing the cancer risk of the cumulative measurements in addition to the individual levels.

Another change Stoiber hopes to inspire with this study is the focus on health in designing the standards. The study is focused on the one in 1 million cancer risk levels, health benchmarks set by the Environmental Protection Agency’s Integrated Risk Information System (IRIS). Current standards are far more lax and set for different reasons.

“The federal MCLs and state MCLs are often set not with purely health protection in mind, but based on cost of water treatment, economic reasoning … a number of different factors,” Stoiber said. “It gets quite complicated and expensive to treat drinking water. But we’re hoping that this kind of an analysis can be a data gathering tool and move us towards better protection of [public] health.”

The paper was published this week in the journal Environmental Health, and can be found at EHJournal.BioMedCentral.com/Articles/10.1186/s12940-019-0475-5.

  Charly Shelton