Recently, the scandal involving coal-to-oil tankers contaminated with edible oil sparked a public outcry, once again bringing food safety and public health to the forefront of public concern. In reality, safety hazards stemming from food have always been present.
In March this year, a study published in *Nature Communications* titled “Serum exposure profiles reveal the risk of chronic diseases in the Chinese population” found that 74 environmentally harmful chemicals—including pesticides, insecticides, veterinary drugs, and plastic degradation products—were frequently detected in the serum of the Chinese population, showing multiple correlations with the risk of developing chronic diseases.
For ordinary people concerned about food safety, what aspects of this research are worth noting? I. Research CredibilityA formidable team of researchers: This study was a collaborative effort between institutes, colleges, and research centres under the Chinese Academy of Sciences, the University of 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 Center for Disease Control and Prevention. Broad scope of subjects: The study covered 5,696 residents across 15 Chinese provinces, including 2,141 healthy individuals and 3,555 patients. It examined associations with 12 types of chronic diseases, including diabetes, hyperuricaemia, obesity, hypercholesterolaemia, hypertriglyceridemia, metabolic syndrome, high diastolic blood pressure, high systolic blood pressure, abdominal obesity, hypertension, high/low-density lipoprotein cholesterol, and hyperlipidaemia.
The most extensive simultaneous chemical detection: Using gas chromatography-mass spectrometry, 267 chemicals were detected in blood samples, including residues of insecticides, plastic degradation products, veterinary drugs, pesticides, and plasticisers.
II. The 267 chemicals remaining in human serum and their sources
The 267 chemicals include insecticides, plastic degradation products, veterinary drugs, pesticides, and plasticisers, of which 74 compounds showed high exposure levels, being detectable in the blood samples of more than half of the volunteers.
● The 267 exposure agents and 74 high-frequency detections analysed in the study.The 97 compounds prioritised for analysis included organochlorine compounds (organochlorine pesticides), organophosphorus compounds (organophosphorus pesticides), herbicides, insecticides, fungicides, veterinary drugs, food additives, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and phthalates. In other words, these are closely linked to agricultural production and daily dietary choices in China. III. Certain organochlorine and fluoride chemicals are closely associated with an increased risk of chronic diseases in the Chinese population.Of these, organochlorine pesticides (OCPs) are linked to hypertension, diabetes, metabolic syndrome, and obesity, while per- and polyfluoroalkyl substances (PFASs) are associated with hyperlipidaemia, obesity, metabolic syndrome, and hyperuricaemia.
● DDT continuously accumulates within the food chain of aquatic organisms and birds; after several stages of magnification, concentrations within organisms can reach up to 10 million times that of the surrounding water. Source: biologywise.com
► Organochlorine Persistent Organic Pollutants
Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) are persistent organic pollutants (POPs) in the environment. Due to their high toxicity, persistence, bioaccumulation, and long-range transport, they concentrate and magnify within organisms through the food chain. This chemical process can lead to adverse effects such as immune dysfunction, reproductive damage, and endocrine disruption.
For humans at the top of the food chain, this toxicity can be magnified by more than 70,000 times. Although the state continuously updates lists of banned and restricted chemicals, and OCPs and PCBs have been prohibited for many years, their accumulation in the environment remains a pressing concern.
● PFAS are found in products such as raincoats, dry powder fire extinguishers, electronic devices, fast-food packaging, and non-stick pan coatings.
► Per- and polyfluoroalkyl substances (PFASs)
Per- and polyfluoroalkyl substances (PFASs) are widely used in industrial production, including food packaging, cookware coatings, and stain-resistant furniture. Humans are exposed to PFASs daily, primarily through drinking water and food, the use of PFAS-containing consumer products, and occupational exposure during the production of related products. PFAS exhibit hepatotoxicity, nephrotoxicity, immunotoxicity, reproductive toxicity, metabolic abnormalities, neurotoxicity, and carcinogenicity, which can lead to various adverse health effects.
IV. OCPs and PFASs residues in the blood of the Chinese population are significantly higher than in other countries
From the 1970s and 80s, countries worldwide began restricting highly toxic organochlorine pesticides, gradually phasing them out by banning their production, sale, and use; however, China did not officially ban organochlorine pesticides until 2002. This is closely linked to the national circumstances of China’s agricultural development. Since the 1950s, the use of ‘666’ reached 4 million tonnes and DDT exceeded 500,000 tonnes, with 13.3 million hectares of farmland contaminated. By the 1990s, when DDT was banned, China’s DDT usage alone accounted for over 20% of the global total.
Most PFASs showed the highest serum concentrations in China and South Korea, while a few specific PFASs were most concentrated in human serum in the United States and Canada. This is closely related to the shift of manufacturing from North America and Europe to the emerging economies of Asia since 2002. V. The highest detection rate of harmful compounds is found in the blood of populations in eastern coastal regions● Left: Serum compound residues across 15 provinces; darker shading indicates higher residue levels. Right: Residue levels of veterinary and other medicines among the tested population are also considerable.Research found that PFASs were most frequently detected in populations from Jiangsu, Zhejiang, and Shanghai, while OCPs were most common in Shanghai, Jiangsu, Hubei, and Chongqing. This may be linked to the higher levels of economic development, industrialisation, proximity to major rivers, and the abundance of edible aquatic products in these regions. Notably, the highest levels of various chemical residues in serum were found in populations from the Yangtze River Delta. A possible explanation is that persistent organic pollutants cannot be effectively removed from wastewater, and are thus transported downstream via groundwater and surface runoff. In this study’s sample, the lowest chemical residues were found in populations from Shaanxi and Guizhou, likely due to lower population densities and less industrial development.
6. Accumulation of harmful environmental chemicals in the blood increases with age
Age is the second major factor in explaining differences in exposure, which may be related to variations in exposure duration and metabolic rates across different age groups. Research indicates 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 pesticide ‘lindane’), p,p’-DDE, pyrene (a raw material for insecticides), and 3-indolebutyric acid (IBA, a plant growth regulator) increase with age, peaking in those over 70. PFAS concentrations also increase with age up to the age of 50.
Conversely, the concentrations of some compounds are inversely proportional to age. The highest residue levels of cyclamate (a metabolite of cyclamate) and acesulfame potassium were found in the serum of children under 10, which may be linked to the consumption of processed foods and drinks containing artificial sweeteners.● Two autumn pear paste drinks from the same brand: the children’s version contains artificial sweeteners such as cyclamate and acesulfame potassium, whereas the standard version actually has a cleaner ingredients list.
VII. The Influence of Education, Income, and Gender on Chemical Residues in the Body
Research indicates that higher levels of education and income correlate with higher residues of harmful chemicals, such as polycyclic aromatic hydrocarbons, OCPs, and polychlorinated biphenyls. OCP levels were significantly higher in women than in men, while levels of PFASs and phthalates (plasticisers) were notably lower. The chemicals most affected by gender were BHC (Lindane), monocyclohexyl phthalate (MCHP), and perfluorooctane sulfonic acid. Gender serves as a key factor in the accumulation and metabolism of chemicals in the human body, which may be linked to differences in body fat proportions and occupational trends.
VIII. Chemical Mixtures Pose More Significant Health Risks Than Single Chemicals
● UK research has found that not only are multiple chemical residues detected in daily food, but soil, rivers, and pollinating bumblebees also fall victim to the “cocktail effect”. Source: Pesticide Action Network UK
Analyses of the association between exposure mixtures and chronic diseases showed that three specific exposure mixtures significantly enhanced hyperuricaemia, hyperlipidaemia, and metabolic syndrome—findings not previously reported in existing research. This “cocktail effect” of chemicals warrants further in-depth study.
It is suggested that future research focus on these chronic diseases and their associated exposure mixtures, prioritising the control of chemicals such as organochlorine pesticides (OCPs), per- and polyfluoroalkyl substances (PFASs), phthalates, and other pesticides (see image below).
Research demonstrates a strong association between specific chemical groups and common chronic diseases, though this does not necessarily imply a definitive causal relationship; further toxicological and epidemiological research is required. However, there is no doubt that these findings will provide guidance for further pollution management and the protection of vulnerable populations.IX. The Persistent Ripple Effect of Pesticide Residue RisksAside from OCPs and PFASs, this study does not delve into the health risks of other pesticides, as the chemical classification of pesticides is as complex as their formulations and compositions. It is difficult to categorise them into broad groups like OCPs and PFASs without targeted correlation studies. The neurotoxicity, hepatotoxicity, and acute or chronic irritant toxicity of pesticides can lead to cancer, malformations, and genetic mutations in organisms to varying degrees—for instance, Highly Hazardous Pesticides (HHPs).
Furthermore, does banning highly toxic organochlorine pesticides solve everything?
To reduce the environmental impact of traditional organochlorine pesticides, several new low-toxicity versions have emerged in recent years. However, research shows these new organochlorine pesticides are widespread in various environmental media, such as soil, water sediments, and surface water. They still pose significant ecological risks and potential threats to human health.
For example, the degradation products of pendimethalin in water are highly hazardous; the production of dichlorobenzophenone can generate DDT as a byproduct, which may affect infant health when released into the environment; and methoxychlor can inhibit sexual behaviour in male quail. We must take the ecological and health risks of new organochlorine pesticides seriously.
Afterword
Technological progress has allowed humanity to create countless new chemical substances. Regardless of the initial intent, the reality is that many chemicals have been proven harmful to the environment and health, and exposure is often inevitable. To minimise these risks, the United Nations established the three international conventions on chemical management to regulate global chemical waste.
Among many chemicals, the risks of Highly Hazardous Pesticides (HHPs) have drawn significant attention.
In 2015, the Fourth International Conference on the Management of Chemicals (ICCM4) passed a resolution recognising HHPs as an issue of international concern and called for concerted action. Consequently, the Food and Agriculture Organization (FAO) and the World Health Organization (WHO) jointly released the “Guidance on Highly Hazardous Pesticides” in 2016.
Pesticide control has also been integrated into biodiversity conservation agendas. In 2022, both the General Office of the State Council’s “Action Plan for the Control of New Pollutants” and the “Kunming-Montreal Global Biodiversity Framework” explicitly included pollutant control in their action plans.
As a major agricultural nation, the health and environmental impacts of pesticide exposure are particularly direct for agricultural producers—the users themselves. Therefore, producers must move beyond a “pesticide-only” mindset and seek Integrated Pest Management (IPM), reducing the haphazard, excessive, or abusive use of pesticides while strengthening their own protection.
To mitigate environmental and health risks, countries establish national Maximum Residue Limits (MRLs) for pesticides in accordance with the WTO’s Agreement on the Application of Sanitary and Phytosanitary Measures (SPS Agreement). These standards are vital technical indicators for assessing the quality and safety of agricultural products and serve as the baseline for environmental and health protection.
Producers must strictly adhere to national pesticide limits, while regulators should provide public outreach and technical training on alternatives to manage risks at the source. Consumers should be mindful of pesticide residues, abandon the pursuit of aesthetically perfect produce, and actively explore alternative consumption choices. By caring about the food on their plates, they can support practices that reduce pesticide risks from production to table.
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 Conservation, and a PhD in Animal Ecology from Yunnan University. Though she initially aspired to be a naturalist, her diverse career path—taking her from the poles to the equator—eventually led her toward social work. She has long been dedicated to research, public education, training, and the management of projects and institutions related to biodiversity conservation, biological resource protection, ecological agricultural development, and the reduction of hazardous chemicals. She possesses extensive experience in project organisation and implementation and enjoys interdisciplinary intellectual exchange from multiple perspectives.Edited by Ze En
