Chemistry: Engine of Inequality or Lever for Equity?

Chemistry is often seen as the science of technical progress, driving major transformations in health, energy, agriculture, and materials. Its economic contributions are widely recognized. Yet its role in social dynamics, particularly in reducing or exacerbating poverty, has often been overlooked. Likewise, the impacts of industrial chemical activities on the most vulnerable populations have long remained poorly documented.

It is only recently, thanks to interdisciplinary research in environmental science, global health, and sustainable development, that the links between chemistry and economic and social vulnerability have been examined more systematically. What emerges is that chemistry profoundly shapes our material conditions of life. It influences access to essential resources, modulates exposure to environmental risks, and determines economic opportunities.

In this context, a contrast becomes clear: while many chemists today are framing their work with greater attention to human dimensions and situations of social and economic fragility, industrial practices do not always align with these concerns. Faced with these challenges, one question arises: are we all equal before chemistry? Does it contribute to widening inequalities among populations? To what extent do its applications, depending on the context, help to alleviate or reinforce situations of inequality?

This is the issue we explore here in a three-part series, the first part of which is published today.

Part 1. Exposure to Pollutants: A Major Chemical Inequality

Prologue

Chicago, 1911. Alice Hamilton, a young physician, walks through the workshops of a metal-processing plant. The heat is stifling, the air thick with dust, and heavy fumes swirl beneath the ceilings. She moves slowly among the machines, observing men exhausting themselves in this suffocating atmosphere, without any respiratory protection. Her notes record weakened bodies, irregular breathing. She is told that the workers—often immigrants and economically vulnerable—fall seriously ill, while others appear to lose their minds. Hamilton quickly identifies the culprit: lead. The workers handle it all day, unaware of the invisible danger infiltrating their lungs and clinging to their clothes.

At the beginning of the 20th century, the United States is the world’s leading producer of this metal. Lead, along with its synthetic derivatives, is ubiquitous in industry, paint, cosmetics, and even some children’s toys. When the automobile industry introduces tetraethyl lead (Pb(C2H5)4) into gasoline to improve engine performance, technical enthusiasm outweighs any caution. But Hamilton sees something more. She understands that behind the innovation lies an unevenly distributed exposure. She knows these lead-based substances accumulate in the body, attack the nervous system, and cause hallucinations, paralysis, and death. Most importantly, she observes that those who suffer the most severe effects are also the ones with the fewest resources to protect themselves.

Alice Hamilton is thus among the first to establish a direct link between industrial chemical exposure, human health, and socio-economic vulnerability. For her, this is not about abstract statistics. Every particle of lead in the air is a tangible risk—clinging to clothes, entering homes, affecting families, and reaching children. Exposure does not stop at the factory walls. It extends into living spaces, where protective capacities are most limited.

Hamilton writes reports, publishes studies, alerts public health authorities. She meticulously documents the effects of industrial poisons, showing that even low doses can be fatal. But she faces powerful industrial interests. When she accuses a major company executive of “murder,” he laughs. Supported by the economic and political logics of her time, industry continues on its path.

Alice Hamilton loses this battle, but she lays the groundwork for a fundamental observation: chemical exposure is not merely a technical or scientific issue. It is profoundly social. It is embedded in power structures, labor relations, and wealth disparities, which determine who is exposed, at what level, and with what consequences.

From Observation to the Revelation of Inequalities

It would take several decades for this relationship to be documented on a large scale. In the 1970s, economist A. Myrick Freeman, drawing on measurement campaigns conducted in the metropolitan areas of St. Louis, Kansas City, and Washington, highlighted a reality that had previously been little formalized: chemical pollutant concentrations are not evenly distributed. They are concentrated in the most disadvantaged neighborhoods. Behind these measurements, a social geography of exposure begins to emerge.

A few years later, the work of Peter Asch and Joseph J. Seneca confirmed this trend at the national level. Their analysis revealed a structured relationship between exposure to chemical pollutants and socio-economic characteristics. They showed that these disparities largely follow income lines, while also noting that other factors, particularly racial, are intertwined. These findings do not merely describe a statistical distribution—they reveal, in outline, differentiated living conditions in the face of the same chemical substances.

In the early 1980s, this reality became even more visible. In 1982, the installation of a polychlorinated biphenyl (PCB) storage site—a persistent and toxic group of chlorinated compounds—near a predominantly African American community in North Carolina triggered a national mobilization. This moment marked a turning point. What had previously been confined to analyses and measurements became a public issue, embodied by residents confronted with the immediate presence of substances whose effects they were experiencing without having consented to their presence.

All of these events and studies converge on a now well-established conclusion: exposure to chemical substances is not randomly distributed but follows precise social, economic, and political lines. The most vulnerable populations—whether due to income, origin, or social position—are also those for whom exposure is strongest, most continuous, and hardest to avoid.

Key Contexts for Understanding the Scale of the Phenomenon

Today, more than 2.3 billion tons of chemical compounds (excluding pharmaceuticals) are produced globally each year—equivalent to 1 kg of chemical compounds per person per day (Figure 1). This production has doubled in less than ten years, with the fastest growth occurring in China and India. The majority of these chemical compounds are petrochemicals (25.7% of sales in 2017), specialty products (26.2%), and polymers (19.2%).

In Europe, chemical production has declined sharply due to international competition and high energy costs. European production reached 282 million tons in 2017 and fell to 224 million tonnes in 2024 (about one-tenth of global production). This output still involves considerable volumes of substances classified as hazardous, despite regulatory efforts. In 2024, European production of chemicals hazardous to human health, according to regulatory criteria, amounted to 172 million tons (over 76% of total production), while production of chemicals hazardous to the environment reached 66 million tons (over 29% of European production). It is worth noting that these concerning figures have declined compared to 2014; European production of substances hazardous to human health decreased by 33 million tons over ten years (-16%). It should also be noted that this hazard classification is based on the intrinsic properties of substances and does not directly indicate the level of risk, which depends on use, exposure, and risk management measures in place.

Figure 1. Key figures on industrial chemical production and its health impacts.

According to the World Health Organization (WHO), exposure to certain chemicals contributes significantly to the global burden of disease. For a still limited number of substances with available data, it is estimated that in 2019 approximately two million deaths (including 500,000 still attributed to lead) and over fifty million disability-adjusted life years (DALYs) could be linked to these exposures. These estimates carry uncertainties and are likely underestimated.

Populations can be affected by direct contamination, for example when living near industrial sites or polluted areas, through air, water, or soil. The WHO emphasizes that these hazards can result from both acute exposures, such as chemical accidents, and chronic exposures, which can lead to respiratory diseases, cancers, endocrine disruptions, neurological disorders, and other health effects. Yet again, these impacts are not evenly distributed. They disproportionately affect the most exposed populations, who are often the least protected and least visible.

A Global Geography of Vulnerabilities

The chemical industry is among the largest and most globalized sectors of the world economy. Yet the geographic distribution of the largest chemical producers has changed significantly over the years and is currently uneven across regions of the world.

During the Industrial Revolution, the first chemical sites—mainly focused on inorganic materials—were concentrated in specific areas of Western Europe. The earliest large-scale locations of the modern chemical industry were in Great Britain, with hubs such as Liverpool and Glasgow. As the chemical industry diversified, other centers emerged in Germany, with the establishment of global giants in the processing of complex chemicals and synthetic dyes. The 20th century amplified this dynamic. Chemical production increasingly incorporated petrochemicals, polymers, synthetic fertilizers, and a wide variety of organic products. The strategic importance of hydrocarbons as raw materials led to the establishment of large chemical facilities near oil refineries or port areas to facilitate the import of raw materials and export of finished products. After World War II, production intensified not only in Europe and the United States but also in Japan, and in the following decades in East Asian regions seeking to modernize their economies.

From the 1980s and 1990s, and especially since the 2000s, the geography of chemical production has continued to transform profoundly under globalization. The historic centers of Western Europe and North America have seen part of their production relocate to lower-cost production regions, notably in China, India, and more broadly across Asia. These countries have developed massive integrated chemical clusters, attracting foreign direct investment from multinationals and becoming export platforms. In India, production hubs have emerged in the states of Gujarat and Maharashtra. In China—now one of the world’s largest producers and consumers of chemicals—major chemical hubs are found along the eastern coast and in provinces such as Jiangsu and Guangdong (Figure 2).

Figure 2. (Left) Location of the world’s largest primary chemical production sites (platform molecules including BTX, methanol, ammonia, ethylene, propylene, and butene) in 2025. (Right) Distribution (%) of major chemical sites by region. Data source: Global Chemicals Inventory, 2026.

Large chemical sites remain widespread in the United States, with particularly high concentrations in southern states such as Texas and Louisiana, due to the significance of fossil fuel extraction and processing in these regions. In Western Europe, major chemical sites are concentrated in heavily industrialized areas with strong transport connections, notably along the Rhine corridor (from the North Sea to Switzerland) and in major port areas such as Rotterdam, Antwerp, and Hamburg.

Socio-Economic Inequalities in Chemical Exposure

Even as the chemical landscape has changed over the decades, it appears that the poorest populations are often located near chemical production or transport sites, or live in environments already polluted by past industrial practices or inadequate waste management infrastructure. This proximity increases their exposure to persistent and toxic pollutants, such as heavy metals, PFAS (per- and polyfluoroalkyl substances), and other persistent organic compounds.

In many low- and middle-income countries, rapid industrialization has historically been accompanied by less developed regulatory frameworks and monitoring capacities. As a result, local populations—often already impoverished—are exposed to higher levels of contaminants in air, water, and soil, which amplifies their vulnerability to chronic diseases and multiple toxic effects. However, this situation is evolving quickly in some countries, notably China, where environmental policies have been significantly strengthened over the past decade, although substantial regional disparities remain.

In certain regions of China, India, Africa, or Latin America, populations living near chemical clusters or industrial port areas face a higher environmental burden than those in wealthier urban neighborhoods, where regulations and monitoring systems can be stricter and better enforced. This phenomenon illustrates what researchers call environmental injustice, in which chemical risks are unevenly distributed across social and economic groups, with the poorest populations often bearing the brunt of the burden.

“Fenceline Communities”: Living on the Edge of Risk

Populations residing in the immediate vicinity—sometimes just a few dozen meters—of industrial facilities such as chemical complexes, refineries, processing units, or other infrastructure emitting toxic substances constitute groups that are particularly exposed to environmental pollution. These areas generally correspond to locations with low land value, which facilitates the settlement of households facing socio-economic vulnerability. These populations are commonly referred to as fenceline communities.

These communities experience chronic, often multi-component exposures to a broad spectrum of environmental contaminants, including volatile organic compounds, polycyclic aromatic hydrocarbons (PAHs), fine particulate matter, and heavy metals. The health effects associated with these exposures—ranging from respiratory and cardiovascular problems to cancer and endocrine disruption—are well documented. Precise quantification remains challenging due to temporal and spatial variability in exposures, as well as potential interactions between different substances.

In the United States, despite substantial strengthening of the regulatory framework since the 1980s, notably through amendments to the Clean Air Act, numerous studies in environmental epidemiology and environmental justice highlight the unequal distribution of pollution sources. Chemical and petrochemical facilities remain disproportionately located near low-income communities and areas with high proportions of racially marginalized populations. This observation is well supported, although individual exposure data remain limited and heterogeneous.

Moreover, evolving industrial practices complicate exposure profiles. The exploitation of unconventional hydrocarbons (such as shale gas), particularly via hydraulic fracturing, involves the use of chemical mixtures whose constituents—biocides, solvents, or surfactants—may induce chronic low-dose exposures that remain insufficiently characterized toxicologically. Acute exposures from accidental releases of hazardous industrial chemicals can also occur, and such events may be exacerbated by the increasing frequency and intensity of extreme weather events linked to climate change, which can damage industrial infrastructure and cause significant contaminant dispersal.

The region commonly known as Cancer Alley in Louisiana provides a frequently cited example in the literature. Stretching along the Mississippi River between New Orleans and Baton Rouge over approximately 140 kilometers, this area hosts a high concentration of petrochemical and hydrocarbon-processing facilities, generating substantial toxic emissions (Figure 3). In certain sections of this corridor, extremely high levels of exposure to toxic pollutants have been recorded. Data on cancer rates are still under study, though they appear higher than elsewhere in Louisiana. Riverfront populations—often low-income and from minority groups—are particularly exposed, illustrating once again the close link between socio-economic disadvantage and environmental overexposure.

Figure 3. Geographic visualization of Cancer Alley based on Figure 2 data.

In this context, scientific literature also emphasizes that risks cannot be considered in isolation. Chemical exposures interact with other social and environmental determinants of health, such as limited access to healthcare, food insecurity, lack of green spaces, or chronic psychosocial stress. This integrated approach, often referred to as “cumulative risk”, highlights an amplification of health vulnerabilities that goes beyond the intrinsic toxicity of individual substances.

Thus, in territories like Cancer Alley, poverty does not merely increase the likelihood of exposure; it also heightens population sensitivity, leading to more severe health impacts and deeper inequalities.

Toxic Legacies and Persistent Exposures

Inequalities in chemical exposure do not only affect populations living near active industrial sites. They also impact communities residing on or near former industrial sites or brownfields. These communities are affected by pollution inherited from past industrial activity, which continues to contaminate soil, groundwater, and air.

With the relocation of some of its chemical and petrochemical industrial activities, Western Europe now has numerous former sites that have become major sources of long-lasting soil and groundwater pollution, due to the persistence of many contaminants such as heavy metals, polycyclic aromatic hydrocarbons (PAHs), chlorinated solvents, PCBs, and per- and polyfluoroalkyl substances (PFAS).

In Europe, a study conducted by the WHO shows that populations living near contaminated sites—particularly former chemical sites—tend to have more disadvantaged socio-economic profiles, reflecting the history of industrialization and contemporary dynamics of social marginalization. These populations are also subject to increased exposure to persistent pollutants, with documented health effects including cancers, respiratory disorders, and endocrine disruption. This pollution is characterized by its long-lasting and diffuse nature. Contaminants from chemical activities can persist in soil for many years or even centuries, migrate into groundwater, or become resuspended in the air as toxic particles or vapors (notably for chlorinated solvents). This phenomenon, known as “vapor intrusion,” is particularly well documented in North American literature, where it constitutes a major exposure pathway in urban areas built on former industrial sites.

In the United States, research on sites under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)—commonly called the Superfund program, a central legal framework for managing industrial chemical liabilities—highlights both historically inadequate hazardous waste management practices and the frequent location of these sites near socially vulnerable urban or suburban areas. Iconic cases illustrate this intersection of industrial legacy and social vulnerability. The Love Canal site in Niagara Falls resulted from Hooker Chemical burying chemical waste beneath a residential area, exposing a predominantly middle-class population to major health risks.

Similarly, the Diamond Alkali site in Newark provides another emblematic example of legacy pollution. Past chemical production activities, particularly herbicides, led to persistent contamination with dioxins, affecting the soil and river sediments over the long term. Located in an urban area with a high proportion of minority populations and disadvantaged socio-economic conditions, this site again illustrates environmental inequality, where the health and ecological costs of industrial pollution persist far beyond the operational period.

Another central aspect is the multiplicity of exposure pathways. Unlike direct industrial exposures, former chemical sites generate indirect and continuous exposures. These can occur through contact with contaminated soil (e.g., in gardens), ingestion of dust, consumption of contaminated water, or food grown in contaminated soil, as well as inhalation of toxic vapors from subsurface contamination. This plurality of exposure vectors makes it difficult for affected populations to anticipate, quantify, or avoid exposure.

Finally, the literature emphasizes that these toxic legacies are embedded in long-term territorial dynamics. Former chemical sites are often located in areas that have experienced deindustrialization, where economic opportunities are limited and populations have few resources to relocate. This situation contributes to a form of cumulative environmental injustice, in which the same territories bear inherited pollution, socio-economic disadvantage, and health vulnerabilities simultaneously.

China: The New Hotspot?

Recent studies highlight that the rapid expansion of chemical industrial parks in China and India is creating intense environmental and health pressures that were neither anticipated nor adequately controlled. A recent study systematically analyzed pollutants in the waters downstream of a large chemical industrial park in Jiangsu Province, focusing on several rivers surrounding the park as well as nearby coastal areas of the Yellow Sea estuary. More than one hundred different contaminants were detected in these aquatic environments. The majority were pesticides, but industrial chemical intermediates, plasticizers, and other compounds of diverse use were also found. Most of the identified contaminants are recognized as hazardous in China, underlining significant ecotoxicological and human health risks.

Analysis of pollution sources shows that the highest pollutant concentrations are found downstream of the park’s industrial zones, particularly at sampling sites near direct discharges or wastewater treatment facilities associated with the industrial park. This study demonstrates a complex and threatening chemical footprint around a Jiangsu industrial park, highlighting the need for stricter management and treatment strategies to protect water quality and surrounding populations.

India: Europe’s Chemical Dump?

The rapid growth of the chemical industry in India is part of a global reconfiguration of production chains, where industrial capacities are gradually being redistributed worldwide. This shift is driven both by growing demand in emerging economies, more competitive production costs, and internationalization strategies of major industrial groups such as Dow, INEOS, and SABIC. In this context, some production capacities in Europe have been reduced or shut down, including sites like Stade or Rheinberg in Germany, or Redcar in the UK, while industrial investments have expanded in regions such as Gujarat, Maharashtra, or Andhra Pradesh in India.

These dynamics do not generally correspond to a direct, one-to-one transfer of European industrial facilities to India. Rather, they result from distinct economic, energy, and geopolitical decisions. Nonetheless, they contribute to a global geographic redistribution of chemical activities, which can partially shift environmental pressures.

In this context, some researchers and observers critically raise the risk of certain territories becoming so-called “chemical cemeteries.” This expression does not imply a uniform or systematic reality, but rather reflects a perception that some regions are concentrating a growing share of industrial activities most exposed to environmental risks, without necessarily having the same regulatory, monitoring, or population protection capacities as industrialized countries.

The case of PFAS illustrates the tensions associated with these dynamics. In Italy, the Miteni plant in Vicenza contaminated extensive groundwater and caused serious health impacts before closing in 2018. After closure, Miteni’s equipment was acquired by the Indian company Laxmi Organic Industries, via its subsidiary Viva Lifesciences, and shipped to Lote Parashuram in Maharashtra, where PFAS production resumed. This demonstrates how technologies considered problematic in Europe can find a second life in India, transferring environmental and health risks.

A similar scenario occurred with another multinational, which dismantled its polymer production facilities in Germany to reinstall them in Dahej, Gujarat, with planned recommissioning by 2028. At the same time, several large companies active in specialty chemicals or cracking closed or downgraded some European units due to strict regulations. Part of the equipment was sold to Indian industrial actors and reinstalled in locations such as Dahej, Mangaluru, Visakhapatnam, Panipat, or Paradeep. These facilities sometimes develop in regions where populations have limited economic resources and environmental oversight is unevenly applied. Residents—often from modest communities reliant on agriculture, fishing, or small trade—bear the direct impacts of pollution. Soil and groundwater contamination by PFAS and other chemicals threatens food security and health while restricting local economic prospects.

Jobs created by these factories often remain precarious and expose workers to toxic substances, reinforcing a vicious cycle of poverty and health vulnerability. This situation raises environmental justice concerns comparable to those observed elsewhere in the world: the most fragile populations are more exposed to industrial pollution while having fewer means to protect themselves or assert their rights.

Belgium: An Example of Environmental Justice?

In Belgium, Article 23 of the Constitution guarantees every person the right to lead a life in accordance with human dignity, which includes the protection of a healthy environment and of health. This constitutional guarantee provides a legal basis to challenge certain forms of pollution or environmental harm, but it remains broadly formulated and does not directly address inequalities in exposure among different social groups. The effective implementation of this right largely depends on regional public policies and the strictness of environmental standards applied, meaning that the Constitution alone is not sufficient to ensure an equitable distribution of environmental risks in the country.

Exposure inequalities do exist in Belgium, often underestimated or less well documented than in other countries. Exposure to various pollutants is influenced both by geographic proximity to industrial and urban sources and by lifestyle, housing, diet, and daily environmental factors. Air pollution from fine particulate matter (PM₂.₅ and PM₁₀) is a major example: these airborne particles penetrate deeply into the respiratory tract, are emitted by multiple sources such as domestic heating, road transport, industry, and waste management, and are considered an important risk factor for human health in Belgium, contributing significantly to the morbidity burden from air pollution. A substantial portion of the Belgian population breathes fine particle levels exceeding the World Health Organization (WHO) guidelines, with exposure varying by region—generally higher in Flanders and in densely urbanized areas. Despite general improvements in recent years, air quality in Belgium remains lower than in several other European Union countries.

Persistent and bioaccumulative pollutants, such as certain PFAS and heavy metals, illustrate a form of legacy pollution with effects that can extend over decades. PFAS, highly resistant to degradation in the environment and the human body, were industrially produced for decades and used in numerous consumer products available in Belgium. They accumulate in soil, water, and human tissue, and are associated with various potential long-term health effects. In the Zwijndrecht region near Antwerp, decades of PFAS production by 3M have caused significant contamination of surrounding soil and water. Large-scale blood testing campaigns revealed that nearly half of residents living within five kilometers of the site had PFAS levels exceeding reference values established by the European Food Safety Authority (EFSA) for certain substances. Additional studies and monitoring campaigns continue to better understand the distribution of these molecules in the human body and their potential links to specific health effects.

This PFAS contamination illustrates that even in a wealthy and highly regulated country, populations can face elevated levels of pollutants inherited from past industrial activities, often with no simple way to mitigate exposure. Legal actions have been initiated by local residents against 3M to obtain compensation for damages caused by this pollution, and civil proceedings are ongoing to recognize these harms as excessive environmental nuisances.

Beyond PFAS, human biomonitoring studies in Belgium have documented exposure to heavy metals such as lead and cadmium in certain areas, including near historical industrial facilities. For example, research around metallurgical plants in Ath revealed measurable increases in blood lead levels among children living nearby, although these levels remain comparable to those observed in other industrialized countries. Such work underscores the importance of directly measuring human exposure to better understand local environmental impacts.

Exposure to these pollutants is not solely determined by industrial proximity: it also depends on social and behavioral factors such as smoking, use of household chemicals, access to healthy housing, and consumption of certain foods, which complicates simple attribution of environmental inequalities to a single source. Available data show that despite relatively advanced regulatory frameworks in Belgium, exposure disparities persist and are often correlated with socio-economic and geographic factors. The production of data by agencies such as Sciensano, which conducts research and monitors environmental exposures and health impacts, is essential to make these inequalities visible and inform policy decisions. However, data collection alone is insufficient to ensure environmental justice: these insights must be integrated into effective public policies that address pollution sources and reduce exposure inequalities, rather than shifting the burden of individual protection onto citizens themselves.

In Belgium, environmental justice therefore remains a concrete and complex challenge, shaped by the interaction of general legislation, industrial legacies, multiple pollution sources, and social disparities. It requires integrated approaches and targeted actions to ensure a truly healthy environment for all.

Pollution and exposure to toxic substances are not just matters of policy—they are fundamentally matters of science. Scientists play a critical role in identifying risks, protecting populations, and turning chemistry into a tool for equity rather than vulnerability.

Key Takeaways

Chemistry is not neutral: it can drive progress but also generate inequalities if risks are poorly managed.
Chemical exposure is socially distributed: poor or marginalized populations face higher exposures and have fewer means to protect themselves.
Globalization amplifies injustices: chemical activities move to countries with less stringent regulations, creating new risk zones.
Science and regulation must be integrated with social justice: producing laws or data alone is not enough; concrete action is required to reduce exposure inequalities.