5 dangerous contaminants in most US water lines have these specialists concerned
Key Takeaways
Drinking water across the US contains a range of harmful contaminants, including pharmaceuticals, heavy metals, and industrial chemicals.
Pharmaceuticals like opioids are difficult to filter out, causing neurological damage and developmental issues in children.
Industrial chemicals such as PFAS, 1,4-dioxane, and nitrates resist standard treatments, leading to increased risks of cancer and severe health hazards in vulnerable populations.
Drinking water safety is a fundamental expectation, yet recent events have cast doubt on the purity of the water flowing from our taps. A 2023 study identified unsafe levels of several toxic compounds in water from wells and community systems across the US, linked to cancers and neurological and developmental disorders.[]
From industrial chemicals to heavy metals, we are seeing more and more contaminants in our drinking water. MDLinx spoke with the experts about the worst water contaminants and how they can impact patient health. Here's what they had to say.
Pharmaceuticals
When patients consume pharmaceuticals, the compounds often undergo incomplete metabolism, resulting in unmetabolized substances excreted into the wastewater system.
Paul Daidone, MD, a board-certified physician in internal medicine and addictionology, points out that opioids, including common drugs like oxycodone, hydrocodone, and even fentanyl, are some of the most troubling categories of pharmaceutical contaminants being increasingly found in tap water.
Adding to this concern, University of Queensland and US researchers recently detected protonitazene—a synthetic opioid four times more potent than fentanyl—in US wastewater for the first time.[] Although the detected levels of these opioids remain low, it's still a concern, given the opioid epidemic in the US.
Michelle Dees, MD, a board-certified psychiatrist, explains, “Like other pharmaceuticals, opioids enter water systems in various conditions. Probably the most common is the careless disposal method when unused prescriptions are flushed down the toilet. Human wastes, because they contain substances that are not digested as opioids, are also still a major source.”
Dr. Daidone points out that “most [waste-processing] plants don’t have the necessary filtration systems to break down the molecular complexity of drugs like opioids. [...] Even home filtration systems can't remove all pharmaceuticals.”
@drbergofficial Drinking Tap Water Part 1 #tapwater #cleanwater #water #flouride #chloramine #drericberg #fyp #estrogen ♬ original sound - Dr. Eric Berg
Lead
Heavy metal contamination, especially lead, is another major issue. Lead often enters the water supply through aging pipes, which still exist in over 9 million homes across the US.[] Water acidity and chlorination can speed up corrosion, increasing lead levels in water.
A 2024 study from JAMA Pediatrics revealed that nearly 70% of children under 6 in Chicago are exposed to lead-contaminated water.[] Neurologist Raveesh Sunkara, MBBS, MS, MCh, warns, “Lead is a neurotoxin, particularly harmful to children’s developing brains. Even small amounts can cause irreversible damage, affecting IQ, behavior, and learning abilities. [...] There’s no safe level of lead exposure."
"The scary thing about lead is that it’s tasteless and invisible, so you might not even realize it's there without testing."
— Raveesh Sunkara, MBBS, MS, MCh (Neurology)
Forever chemicals
Per- and polyfluoroalkyl substances (PFAS), or "forever chemicals," contaminate over 45% of US tap water, according to a 2023 report from the US Geological Survey.[] Oncologist Sandeep Nayak, MBBS, MRCS (UK), DNB, explains, "PFAS primarily enter drinking water through industrial discharges from factories," noting that their persistence is compounded by conventional treatment plants’ inability to remove them.
Dr. Nayak highlights the health risks, including the link between PFAS exposure and certain cancers, such as kidney, testicular, liver, prostate, and pancreatic cancers. “These chemicals interfere with hormonal functions and immune responses, and even low-level exposure over many years can increase cancer risk,” he says.
1,4-Dioxane
1,4-dioxane, a solvent stabilizer, is highly soluble and resistant to natural degradation, allowing it to spread extensively through groundwater. Improper disposal and industrial activities have made it a long-lasting water contaminant.
A 2023 review indicates contamination from both historical releases and current use of personal care and cleaning products.[] However, the compound is not labeled on product ingredients because it is an unintended byproduct formed during manufacturing processes, making it difficult for consumers to identify and avoid.
Board-certified physician John Lowe, MD, notes, "Some cosmetic products that use 1,4-dioxane as a stabilizer can be sources of surface and groundwater pollution when these products are removed and drained into sewerage."
Recently, the City of Sanford, FL, filed a lawsuit against companies allegedly responsible for contaminating its water supply with 1,4-dioxane.[] The chemical has been linked to a former manufacturing facility that ceased operations in the early 2000s. The Environmental Protection Agency (EPA) classifies 1,4-dioxane as a likely carcinogen.
Dr. Lowe also notes that “People with long periods of exposure to this compound tend to suffer liver and kidney impairment, as these are the chief organs responsible for the metabolism and excretion of the compound."
Nitrates
“Nitrate is one of the contaminants most frequently found in violation of health-based standards in US drinking water,” according to environmentalists writing in Environmental Health.[]
Board-certified physician Raj Dasgupta, MD, FACP, FCCP, FAASM, explains that farm fertilizers are one of the biggest sources of nitrate pollution in water. “When it rains or fields are irrigated, excess nitrates get washed into rivers and groundwater. Septic systems can also leak nitrates into the water, especially in rural areas, adding to the problem."
Dr. Dasgupta explains nitrate exposure is especially dangerous for infants, leading to conditions like methemoglobinemia, or "blue baby syndrome." "Nitrates dissolve easily in water, and don’t settle down like dirt or bacteria," he says. "Basic water treatment methods, like filtration and chlorination, aren’t enough to catch them. Removing nitrates usually requires specialized equipment, like reverse osmosis filters, which can be expensive and not always available."
Guidance for the clinic
Replacing aging pipes can drastically reduce exposure to lead and heavy metal contamination.
Dr. Sunkara advises patients to flush pipes by running cold water for several minutes before drinking, especially in older homes. He also recommends using certified filters that effectively remove lead and other toxins. For patients with higher risks, reverse osmosis systems can help reduce exposure to pharmaceuticals and nitrates.
To keep children safe from toxic contaminants in water, Dr. Dasgupta recommends opting for bottled water for infant formula preparation and installing advanced water filters. He also advises against mixing baby formula with tap water.
Lastly, patients should be advised to dispose of unused medications properly, to reduce pharmaceutical contamination. Physicians can educate patients about drug take-back programs and discourage flushing medicines down the toilet.
What this means for you
The issue of drinking water contamination has reached a point where it demands our urgent attention. However, until stricter guidelines and regulations are implemented on a larger scale, simple advice for patients, like testing water, using certified filters, and properly disposing of meds, can help reduce exposure risks.