Water pollutants 1/2: What Can Actually Be Found in Our Water

📌 This article is Part 1 of our water pollutants series. Part 2 is now available: Water pollutants 2/2: Which Water Should You Drink and How Should You Filter It? →

PFAS in water. Pesticides in food. Phthalates in certain plastics. Metals in soils, pipes or certain foods. Microplastics in bottled water, air and food.

Environmental pollutants are all around us. But what are their actual effects?

When we talk about "toxins," we are in fact grouping together very different substances: PFAS, pesticides, bisphenols, phthalates, metals, micro- and nanoplastics, as well as certain industrial by-products.

Some can interfere with our hormonal system. Others affect the nervous system, kidneys, liver or immune system.

Water is an excellent place to start because we consume it every day. It also illustrates something much broader: what we produce, use or release can circulate between soils, water, air, food and, ultimately, our bodies.

This article looks at the main families of pollutants that can be found in water, where they come from and what we currently know about their health effects.

First: what does "safe drinking water" actually mean?

In France, tap water is subject to regular health monitoring. Water declared safe to drink must comply with microbiological and chemical requirements, as well as quality limits established for various contaminants.

But there is an important distinction:

compliant does not mean free from pollutants.

A substance can be present below its regulatory limit and the water can still be considered compliant.

And importantly, we do not test for everything that could potentially be present in the water.

This is particularly clear with PFAS: since January 2026, French regulations require monitoring the combined concentration of 20 PFAS, with a quality limit set for this total. Yet the PFAS family includes thousands of substances.

Detecting a substance does not automatically mean that it poses a health risk at the concentration found.

But regulatory thresholds cannot fully capture the complexity of our exposure either: duration, frequency, persistence of certain substances, vulnerable periods of life and simultaneous exposure to multiple compounds all matter.

The real question therefore becomes: which contaminants can be found in water, where do they come from and what do we know about their effects?

The main contaminants found in water

Different families of contaminants do not share the same sources, mechanisms or level of evidence regarding their effects on health.

| Pollutant / family | How does it get into the water? | Main health risks studied | | --- | --- | --- | | PFAS | Industrial activities, firefighting foams, waste, certain agricultural uses and PFAS-containing products; long-term contamination of soils and groundwater | For some PFAS: increased cholesterol, changes in liver enzymes, reduced immune response to certain vaccines, hypertension during pregnancy, modest reductions in birth weight; PFOA associated with kidney and testicular cancers | | Pesticides and metabolites | Runoff and infiltration from agricultural areas; metabolites are molecules formed when the pesticide is transformed in the environment | Vary according to the substance: neurological, endocrine, reproductive or carcinogenic effects documented for certain compounds, particularly at high or occupational exposure levels | | Nitrates / nitrites | Fertilizers and livestock effluent contaminating groundwater and surface water | At high concentrations, notably associated with a risk of methemoglobinemia in infants under 6 months | | Lead | Mainly certain old pipes, connections or plumbing systems | Neurotoxicity, particularly in children; renal and cardiovascular effects with chronic exposure | | Disinfection by-products | Reactions between disinfectants used to make water microbiologically safe and naturally occurring substances in the water | Certain compounds are monitored for potential chronic effects; disinfection nevertheless remains essential to prevent microbiological risks | | Perchlorates | Certain industrial or historical contamination, particularly linked to explosives and munitions | Can inhibit iodine uptake by the thyroid and interfere with thyroid hormone synthesis | | Micro- and nanoplastics | Environmental pollution, treatment processes, distribution networks and packaging | Cardiovascular, inflammatory, oxidative and cellular effects are being studied; the clinical consequences of everyday exposure remain incompletely understood |

Why PFAS deserve particular attention

Among all these contaminants, PFAS occupy a particular place when we talk about water.

Per- and polyfluoroalkyl substances are a huge family of molecules that have been used for decades to make materials resistant to water, grease, stains and heat.

They have been found or used in certain waterproof textiles, food packaging, coatings, cosmetic products, firefighting foams and industrial processes.

The problem is their extreme persistence.

Once released into the environment, some PFAS break down very slowly and can contaminate soil, groundwater and surface water, and eventually the food chain. Some PFAS have a half-life in the body of around 3 to 5 years.

This is why they are known as "forever chemicals."

And unlike some contaminants for which water represents a relatively minor source, drinking water and food are major pathways of PFAS exposure. In areas where drinking water is contaminated, water can even become the primary source of exposure.

This explains why monitoring PFAS in water has become a major public health issue.

One particularly striking example is TFA, or trifluoroacetic acid. During a national campaign conducted by ANSES between 2023 and 2025, it was detected in 92% of the raw and distributed water samples analyzed.

This does not, of course, mean that 92% of French water poses a health risk.

It does show, however, just how widely certain fluorinated compounds are now distributed throughout the water cycle.

And what are their effects on health?

For several PFAS, higher exposure has been associated with increased LDL cholesterol, changes in liver enzymes and a reduced antibody response following certain vaccinations, particularly in children.

During pregnancy, higher concentrations of certain PFAS have also been associated with a greater risk of gestational hypertension or pre-eclampsia.

Regarding cancer, in 2023 the International Agency for Research on Cancer classified PFOA as carcinogenic to humans and PFOS as possibly carcinogenic to humans. For PFOA, human data notably concern kidney and testicular cancers.

This is why their presence in water deserves particular attention: some of these substances are persistent, exposure may occur daily, and the effects of several PFAS are now documented in humans.

What about bottled water?

It may seem intuitive to assume that bottled water is automatically safer than tap water.

It is not that simple.

Bottled water also comes from a natural water source that may be exposed to environmental contaminants. Spring water, natural mineral water and water made potable through treatment are also different categories subject to different regulations.

Then there is the question of the container itself.

A study published in 2024 using a technique capable of detecting extremely small particles estimated an average of around 240,000 micro- and nanoplastic particles per litre in three American bottled water brands analyzed, the majority of which were nanoplastics.

This study cannot be extrapolated to all bottled water and does not demonstrate that these particles cause clinical effects at the concentrations detected.

It simply reminds us of one important point:

bottled water does not automatically mean higher-quality water.

Does "the dose make the poison"?

Yes, dose remains fundamental in toxicology.

But dose alone is not enough to describe our environmental exposure.

A significant one-off exposure is not equivalent to a small amount absorbed every day for years.

Duration and frequency matter.

Persistence matters too: some compounds are rapidly eliminated, whereas certain PFAS can remain in the body for several years.

The timing of exposure can also matter. Pregnancy, fetal development and childhood, for example, are periods of particular concern for several contaminants.

Finally, we are never exposed to a single isolated molecule.

Our water may contain several substances while we are simultaneously exposed to other compounds through food, air or our everyday environment.

Several substances may therefore act simultaneously through similar or different biological mechanisms: this is commonly referred to as the cocktail effect.

Research is increasingly focusing on these chronic and cumulative exposures, rather than looking only at acute poisoning caused by high doses.

The goal is therefore neither to assume that every molecule detected is dangerous nor to try to achieve zero exposure.

It is to understand which sources meaningfully contribute to our exposure and which ones we can reasonably reduce.

What Part 2 covers

Now that we know what water can contain, one question remains: what can we actually do about it?

Part 2 looks at how to assess the quality of the water supplied to your home and compares the main filtration systems to understand what they actually remove, their limitations and how to choose a solution suited to your water rather than to a marketing promise.

It also looks at bottled water, when testing your own water may be useful and why choosing a filter should begin with understanding what you are actually trying to remove.

Because understanding our environmental exposure should not make us anxious about everything around us.

It should help us better identify the exposures over which we genuinely have some control.

Measuring your own exposure

Lucis can also help you objectively assess part of your exposure.

Our Environmental Toxicology Analysis measures three toxic metals in the blood: lead, mercury and cadmium.

The aim is to provide concrete data that can help identify unusually high exposure and, above all, investigate where it may be coming from: diet, smoking, environment, housing or occupational exposure.

Measuring is only the starting point. The real value lies in knowing what to do with the data, and Lucis guides you from measurement all the way through to concrete actions.

Scientific references

Barry V, Winquist A, Steenland K. Perfluorooctanoic acid (PFOA) exposures and incident cancers among adults living near a chemical plant. Environmental Health Perspectives. 2013;121(11-12):1313-1318. doi:10.1289/ehp.1306615
Caporale N, Leemans M, Birgersson L, et al. From cohorts to molecules: adverse impacts of endocrine disrupting mixtures. Science. 2022;375(6582):eabe8244. doi:10.1126/science.abe8244
Costello E, Rock S, Stratakis N, et al. Exposure to per- and polyfluoroalkyl substances and markers of liver injury: a systematic review and meta-analysis. Environmental Health Perspectives. 2022;130(4):046001. doi:10.1289/EHP10092
Fenton SE, Ducatman A, Boobis A, et al. Per- and polyfluoroalkyl substance toxicity and human health review: current state of knowledge and strategies for informing future research. Environmental Toxicology and Chemistry. 2021;40(3):606-630. doi:10.1002/etc.4890
Gao X, Ni W, Zhu S, et al. Per- and polyfluoroalkyl substances exposure during pregnancy and adverse pregnancy and birth outcomes: a systematic review and meta-analysis. Environmental Research. 2021;201:111632. doi:10.1016/j.envres.2021.111632
Goodrich JA, Walker D, Lin X, et al. Exposure to perfluoroalkyl substances and risk of hepatocellular carcinoma in a multiethnic cohort. JHEP Reports. 2022;4(10):100550. doi:10.1016/j.jhepr.2022.100550
Grandjean P, Andersen EW, Budtz-Jørgensen E, et al. Serum vaccine antibody concentrations in children exposed to perfluorinated compounds. JAMA. 2012;307(4):391-397. doi:10.1001/jama.2011.2034
Gui SY, Qiao JC, Xu KX, et al. Association between per- and polyfluoroalkyl substances exposure and risk of diabetes: a systematic review and meta-analysis. Journal of Exposure Science & Environmental Epidemiology. 2023;33(1):40-55. doi:10.1038/s41370-022-00464-3
Marfella R, Prattichizzo F, Sardu C, et al. Microplastics and nanoplastics in atheromas and cardiovascular events. New England Journal of Medicine. 2024;390:900-910. doi:10.1056/NEJMoa2309822
Marks KJ, Howards PP, Smarr MM, et al. Prenatal exposure to mixtures of persistent endocrine-disrupting chemicals and birth size in a population-based cohort of British girls. Epidemiology. 2021;32(4):573-582. doi:10.1097/EDE.0000000000001351
Park SK, Wang X, Ding N, et al. Per- and polyfluoroalkyl substances and incident diabetes in midlife women: the Study of Women's Health Across the Nation (SWAN). Diabetologia. 2022;65(7):1157-1168. doi:10.1007/s00125-022-05695-5
Qian N, Gao X, Lang X, et al. Rapid single-particle chemical imaging of nanoplastics by SRS microscopy. Proceedings of the National Academy of Sciences. 2024;121(3):e2300582121. doi:10.1073/pnas.2300582121
Winquist A, Steenland K. Modeled PFOA exposure and coronary artery disease, hypertension, and high cholesterol in community and worker cohorts. Environmental Health Perspectives. 2014;122(12):1299-1305. doi:10.1289/ehp.1307943

Institutional sources:

ANSES National PFAS measurement campaign in drinking water, 2025.
ANSES Perchlorate ions: assessments and recommendations.
ANSES / French Ministry of Health Pesticides in tap water.
French Ministry of Health PFAS and drinking water.
World Health Organization (WHO) Lead poisoning and health.

The information shared in this article is provided for educational purposes only. It is not a substitute for medical advice, diagnosis or care from a qualified healthcare professional.