Recently, the chaotic practice of using tankers intended for coal-derived oil to also transport edible oils has sparked public outrage, once again bringing food safety and public health to the forefront of national concern. In truth, hidden risks in our food supply have always been present.
In March this year, a study published in *Nature Communications*, titled *Serum Exposure Landscape Reveals the Risk of Chronic Diseases in the Chinese Population*, found that 74 environmentally hazardous chemicals—including pesticides, insecticides, veterinary medications, and plastic degradation by-products—were frequently detected in the blood serum of participants. These findings reveal multiple correlations with the development of chronic diseases.
What does this study mean for everyday individuals concerned about food safety?1. Study CredibilityA robust research team: The study was a collaborative effort involving research institutes, faculties, and centres affiliated with the Chinese Academy of Sciences, the University of the Chinese Academy of Sciences, the Liaoning Provincial Key Laboratory of Metabolomics, the State Key Laboratory of Environmental Health, Huazhong University of Science and Technology, China Medical University, and the Chinese Centre for Disease Control and Prevention.Extensive subject coverage: The research included 5,696 residents across 15 provinces in China, comprising 2,141 healthy individuals and 3,555 patients. It examined associations with 12 chronic conditions, including diabetes, hyperuricaemia, obesity, hypercholesterolaemia, hypertriglyceridaemia, metabolic syndrome, elevated diastolic pressure, elevated systolic pressure, abdominal obesity, hypertension, high LDL cholesterol, and hyperlipidaemia.
Broadest chemical screening to date: Using gas chromatography–mass spectrometry, the study screened blood samples for 267 different chemicals, assessing residual levels of insecticides, plastic degradation by-products, veterinary medications, pesticides, and plasticisers.
2. The 267 Chemicals Detected in Human Blood Serum and Their Sources
The 267 chemical substances analysed encompass insecticides, plastic degradation products, veterinary medicines, pesticides, plasticisers, and more. Exposure levels are notably high for 74 of these compounds, with more than half of the volunteer blood samples testing positive for them.
● The 267 exposures screened in the study, alongside the 74 compounds most frequently detected.The study prioritised the analysis of 97 specific compounds, encompassing organochlorines (organochlorine pesticides), organophosphates (organophosphate pesticides), herbicides, insecticides, fungicides, veterinary medicines, food additives, polychlorinated biphenyls, polycyclic aromatic hydrocarbons, and phthalates, among others. Put simply, these chemicals are deeply intertwined with domestic agricultural practices and everyday dietary habits.3. Certain organochlorine and fluorinated chemicals show a strong link to elevated chronic disease risk in the Chinese population.Of these, organochlorine compounds (OCPs) have been linked to hypertension, diabetes, metabolic syndrome, and obesity. Meanwhile, per- and polyfluoroalkyl substances (PFAS) are associated with hyperlipidaemia, obesity, metabolic syndrome, and hyperuricaemia.
●DDT continuously accumulates within the food chains formed by aquatic life and birds. Through several stages of biomagnification, concentrations in living organisms can reach up to ten million times those found in the surrounding water. Image source: biologywise.com
► Organochlorine Persistent Organic Pollutants
Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) are classified as persistent organic pollutants within the environment. Characterised by high toxicity, persistence, bioaccumulation, and long-range transport, these substances undergo processes of concentration and biomagnification as they pass through the food chain, leading to adverse effects such as immune dysfunction, reproductive damage, and endocrine disruption.
For humans at the apex of the food chain, these toxic impacts can be magnified by a factor of over seventy thousand. Although governments continually update regulations to ban and restrict chemical usage, and despite OCPs and PCBs having been prohibited for many years, their ongoing accumulation in the environment remains a matter of serious concern.
●Products such as raincoats, fire extinguisher powder, electronic devices, fast-food packaging cartons, and non-stick pan coatings all contain PFAS.
► Per- and polyfluoroalkyl substances (PFASs)
Per- and polyfluoroalkyl substances (PFASs) are widely used in industrial applications such as food packaging, tableware coatings, and stain-resistant furniture. The public encounters PFASs daily, primarily through drinking water and food, the use of consumer products containing these substances, and occupational exposure during their manufacture. PFASs are linked to liver and kidney toxicity, immune system disruption, reproductive toxicity, metabolic disorders, neurotoxicity, and carcinogenicity, posing a wide range of adverse effects on human health.
4. Residual levels of OCPs and PFASs in the blood of the Chinese population are significantly higher than in other countries
From the 1970s and 1980s onwards, nations worldwide began restricting highly toxic organochlorine pesticides, progressively phasing them out through bans on production, sale, and application. China, however, did not formally prohibit these chemicals until 2002—a decision deeply rooted in the country’s agricultural realities. Since the 1950s, China had deployed roughly 4 million tonnes of 666 (Benzene Hexachloride) and more than 500,000 tonnes of DDT, resulting in contamination across 13.3 million hectares of cropland. Even by the 1990s, when DDT use was finally curtailed, China alone had consumed over 20% of the world’s total DDT.
Serum concentrations of most PFASs are highest in China and South Korea, while a handful of specific PFASs peak in the blood of individuals in the United States and Canada. This pattern is closely linked to the migration of manufacturing from North America and Europe to emerging Asian economies since 2002.5. Eastern coastal regions show the highest detection rates of harmful compounds in human blood● Left: Compound residue levels in the blood serum of populations across 15 provinces; darker colours indicate higher concentrations. Right: Residue levels of veterinary drugs and other pharmaceuticals among the tested populations in these 15 provinces are also substantial.Research has found that PFASs are most frequently detected in populations across Jiangsu, Zhejiang, and Shanghai, while OCPs are most commonly found in Shanghai, Jiangsu, Hubei, and Chongqing. This may be linked to these regions’ higher levels of economic development, advanced industrialisation, proximity to major rivers, and abundant edible aquatic products. Notably, residents of the Yangtze River Delta exhibit the highest levels of various chemical residues in their serum. A plausible explanation is that persistent organic pollutants are not effectively removed from wastewater, and are subsequently transported downstream via underground and surface runoff. Among the study’s samples, populations in Shaanxi and Guizhou showed the lowest chemical residue levels in their serum, likely attributable to lower population densities and less industrial development in those areas.
6. The Older the Individual, the Greater the Accumulation of Harmful Environmental Chemicals in the Blood
Age is the second most significant factor explaining exposure differences, likely reflecting variations in exposure duration and metabolic rates across different age groups. The study found that the accumulation of most chemicals, such as OCPs and PFASs, in human serum increases with age. Specifically, concentrations of beta-HCH (used in the manufacture of the pesticide lindane), p,p’-DDE, pyrene (an insecticide ingredient), and indole-3-butyric acid (IBA, a plant growth regulator) all rise with age, peaking in individuals over 70. PFAS levels also increase with age, up until the age of 50.
Conversely, the concentration of certain compounds is inversely proportional to age. Children under ten have the highest serum residual levels of cyclamic acid (a cyclamate metabolite) and acesulfame, likely linked to their consumption of processed foods and beverages containing sugar substitutes.● Two pear paste drinks from the same brand: the children’s version contains sugar substitutes such as cyclamate and acesulfame, whereas the ingredient list for the standard version is actually cleaner.
VII. Education, income and gender influence the residual levels of chemicals in the body
Research indicates that higher education and income levels are associated with greater residual levels of harmful chemicals, including polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs). Women exhibit significantly higher OCP levels than men, but significantly lower concentrations of PFASs and phthalates (plasticisers). The chemicals most markedly influenced by gender are β-BHC (lindane), monohexyl phthalate (MCHP) and perfluorooctane sulfonic acid (PFOS). Gender has emerged as a crucial factor in how chemicals accumulate and are metabolised in the human body, likely owing to differences in body fat proportion and occupational exposure patterns.
VIII. Chemical mixtures pose a more pronounced health risk than single chemicals
● UK research has found that chemical residues are detected not only in everyday foods, but also in soil, rivers, and pollinating bumblebees, none of which are immune to the “cocktail effect”. Source: Pesticide Action Network UK
Analysis of the association between exposure mixtures and chronic diseases revealed that all three groups of mixtures significantly exacerbated hyperuricaemia, hyperlipidaemia, and metabolic syndrome—an interaction not previously reported in the literature. This chemical “cocktail effect” certainly warrants further in-depth investigation.
Future research should prioritise these chronic conditions alongside their associated exposure mixtures, particularly chemicals earmarked for risk control. These primarily include organochlorine pesticides (OCPs), per- and polyfluoroalkyl substances (PFAS), phthalates, and other agricultural pesticides (see figure below).
While the research demonstrates a strong correlation between specific chemical groups and common chronic diseases, correlation does not equate to a definitive causal link; further in-depth toxicological and epidemiological studies are required. Nevertheless, there is no doubt that these findings will inform future pollution management strategies and help protect vulnerable populations.Nine: Pesticide Residue Risks Ripple Outward and PersistBeyond OCPs and PFAS, this study does not detail the health risks posed by other pesticides. Pesticide classification is as intricate as their formulations, active ingredients, and chemical compositions, making it difficult to group them broadly in the manner of OCPs or PFAS without targeted correlational studies. Furthermore, the neurotoxicity, hepatotoxicity, irritant properties, and acute or chronic toxicity of these substances can induce cancer, congenital malformations, and genetic mutations to varying degrees across living organisms—a risk particularly acute with Highly Hazardous Pesticides (HHPs).
Moreover, does simply banning highly toxic organochlorine pesticides truly put us out of danger?
To mitigate the environmental footprint of traditional organochlorine pesticides, several newer variants with lower toxicity have been introduced in recent years. Yet research indicates that these newer compounds are now widespread across various environmental media—including soil, aquatic sediments, and surface waters—continuing to pose substantial ecological risks and potential threats to human health.
For instance, the aqueous degradation products of diquat prove highly hazardous; the manufacture of dicofol yields DDT as a by-product, which, once released into the environment, can adversely affect infant health; and methoxychlor has been shown to suppress sexual behaviour in male quail. These examples underscore the pressing need to address both the ecological and health risks associated with newer organochlorine pesticides.
Postscript
Technological progress has led to the creation of countless novel chemical substances. Regardless of their original intent, the reality is that many have been shown to harm both the environment and human health, and public exposure to them is now unavoidable. To minimise these risks as far as possible, the United Nations established the three international chemicals conventions to govern global chemical waste management.
Among the myriad chemicals in circulation, the risks posed by high-risk pesticides have drawn particular attention.
In 2015, the Fourth International Conference on Chemicals Management (ICCM4) re-affirmed a resolution recognising high-risk pesticides as a matter of international concern, calling for coordinated action to address the issue. Shortly thereafter, the Food and Agriculture Organisation (FAO) and the World Health Organisation (WHO) jointly published the *Guidance on High-Risk Pesticides* in 2016.
Pesticide control is also gradually being integrated into biodiversity conservation agendas. In 2022, both the State Council’s *Action Plan for the Control of Emerging Pollutants* and the *Kunming-Montreal Global Biodiversity Framework*, adopted under the Convention on Biological Diversity, explicitly incorporated pollutant governance into their respective action plans.
As a major agricultural nation, China is particularly affected by the health and environmental impacts of pesticide exposure, with farmers and other end-users bearing the brunt. Consequently, those who apply pesticides must first move beyond a pesticide-first mentality, adopt integrated pest management strategies, strengthen personal protective measures, and curb the misuse, overuse, and excessive application of these chemicals.
To mitigate the environmental and health risks associated with harmful chemicals, countries establish their own Maximum Residue Limits (MRLs) for pesticides in accordance with the WTO’s *Agreement on the Application of Sanitary and Phytosanitary Measures* (SPS Agreement). This standard serves as a critical technical benchmark for assessing the quality and safety of agricultural products, and forms the baseline for protecting environmental and public health.
Producers must strictly adhere to national pesticide regulations. Regulators should step up public awareness campaigns and provide technical training on pesticide alternatives, managing health and environmental risks at the source. Meanwhile, consumers need to become more mindful of pesticide residues, move away from an obsession with cosmetically perfect produce, actively seek out alternative purchasing options, and pay closer attention to what ends up on their plates. By doing so, they can support practical initiatives that reduce pesticide-related risks from farm to fork.
Foodthink AuthorDou HongDeputy Secretary-General of the Yunnan Green Environment Development Foundation. She holds an undergraduate degree in Wildlife Conservation and Utilisation, a master’s in Forest Protection, and a PhD in Animal Ecology from Yunnan University. Initially dreaming of becoming a naturalist, her career took her through landscapes from the poles to the equator, ultimately leading her into social work. She has long been dedicated to research, advocacy, education, and training focused on biodiversity conservation, biological resource protection, sustainable agroecology development, and the reduction of hazardous chemicals. With extensive experience in project organisation and institutional management, she values interdisciplinary dialogue and the collision of perspectives across different fields.Edited by Ze En
