The 7 biomarkers that reveal your exposure to water pollutants

This listicle is inspired by our two-part series on water pollutants: Part 1: what can actually be found in our water → and Part 2: which water should you drink and how should you filter it? →

Water declared safe to drink is not water free from pollutants, and we do not test for everything that could be present. Testing your water therefore tells you about one potential source of exposure, but not what your body has actually absorbed, nor where your overall exposure comes from.

That is exactly what blood biomarkers measure. Here are the seven our series puts forward, what each one reflects, and when it is worth looking at.

1. Lead: the metal your home can add to your water

Lead is generally absent from the water at the source and when it leaves treatment facilities. It appears later, in the final few metres.

Why it matters: lead can be released from certain old pipes, connections or plumbing components. The documented effects are neurotoxicity, particularly in children, along with renal and cardiovascular effects with chronic exposure.

Exposure situations to check:

• an older home or suspected old plumbing;

• a known local issue involving a particular contaminant;

• proximity to a particularly exposed industrial or agricultural area;

• use of a private well or private water source.

Key takeaway: your municipal analyses say nothing about the final few metres between the public network and your glass. Blood lead measures what actually reached you.

2. Mercury: the measurement that widens the search beyond the tap

Mercury does not mainly come from water, and that is precisely why measuring it is useful.

Why it matters: water testing tells you about one potential source of exposure. It does not tell you what has actually been absorbed by your body, nor where your overall exposure comes from. Mercury is one of the three toxic metals measured in the blood by the Lucis Environmental Toxicology Analysis.

Exposure situations to check:

• diet;

• smoking;

• environment;

• occupational exposure.

Key takeaway: unusually high mercury points the investigation towards diet or environment rather than your tap.

3. Cadmium: the third metal of the blood trio

Like mercury, cadmium is read in the blood and then put into context.

Why it matters: cadmium completes the lead, mercury, cadmium trio measured by the Environmental Toxicology Analysis. The aim is to identify unusually high exposure and then put it into context depending on the metal concerned.

Exposure situations to check:

• diet;

• smoking;

• environment;

• occupational exposure.

Key takeaway: measure first, trace the source second. That order is what makes the data useful.

4. LDL cholesterol: a cardiovascular marker sensitive to PFAS

A standard lipid panel marker, associated here with an environmental exposure.

Why it matters: for several PFAS, higher exposure has been associated with increased LDL cholesterol. And drinking water and food are major pathways of PFAS exposure: in areas where drinking water is contaminated, water can even become the primary source.

Exposure situations to check:

• local water affected by PFAS;

• proximity to a contaminated area;

• daily, prolonged exposure, since PFAS are extremely persistent.

Key takeaway: an LDL that is explained neither by diet nor by genetics deserves a look at the environment too.

5. Liver enzymes: ALT, AST and GGT

The liver is the second system where human PFAS data are best documented.

Why it matters: for several PFAS, higher exposure has been associated with changes in liver enzymes.

Exposure situations to check:

• local water affected by PFAS;

• proximity to a contaminated area;

• daily, prolonged exposure.

Key takeaway: these enzymes are never interpreted on their own. They make sense within the rest of your panel and your exposure context.

6. TSH and iodine: thyroid function against perchlorates

Some water contaminants have a very precise biological target. For perchlorates, it is the thyroid.

Why it matters: perchlorates can inhibit iodine uptake by the thyroid and interfere with thyroid hormone synthesis. They come from certain industrial or historical contamination, particularly linked to explosives and munitions.

Exposure situations to check:

• an area affected by perchlorate contamination;

• a local industrial or military history.

Key takeaway: if perchlorates are an issue where you live, thyroid function is the marker that translates that exposure.

7. Calcium and magnesium: the biomarker your filter can shift

The only one on this list that the solution, rather than the pollutant, can move.

Why it matters: reverse osmosis removes a large proportion of the calcium and magnesium naturally present in water. These minerals can contribute to our nutritional intake, sometimes to a meaningful degree when the water is particularly mineral-rich. The WHO does not, however, define a minimum concentration of calcium, magnesium or hardness required for health in drinking water, because the available evidence is insufficient to establish a universal value, and food remains a major source.

Exposure situations to check:

• reverse-osmosis water that has become your main drinking water over the long term;

• a reverse osmosis system with no remineralisation stage.

Key takeaway: if reverse osmosis becomes your everyday water, choosing a system that remineralises it appropriately is a reasonable option.

Conclusion

These seven markers tell the same story from two angles. Three of them, lead, mercury and cadmium, measure directly what your body has absorbed. The others, LDL, liver enzymes, thyroid function, calcium and magnesium, show what that exposure can shift in your biology, or what your filtration can take out of it.

That is exactly what Lucis does: analyse these biomarkers in full context, interpret the results in the light of your lifestyle and your environment, then give you a personalised plan adapted to your biological profile, rather than a simple "in range or out of range". Our Environmental Toxicology Analysis measures the three toxic metals in the blood, and the point is never to measure for the sake of measuring: it is to know what to do with the data.

Note: this article does not give reference values. Optimal ranges depend on your age, sex, context and exposure history, and should be discussed with your doctor.

The information in this article is provided for educational purposes only and does not constitute medical advice or a medical recommendation. Please consult a healthcare professional before modifying your diet, training, or supplementation.