Introduction The heavy metal elements cadmium (Cd) and zinc (Zn) often coexist in nature, making the environmental media more prone to compound pollution. However, research on the toxic effect of the Cd-Zn combination is still lacking, and the underlying toxic mechanisms remain unclear.Methods Therefore, in this experiment, we established four treatment groups with different ratios of Cd-Zn compound stress for the broad bean, Vicia faba L., and aphids, Megoura crassicauda, to explore the growth and physiological adaptation mechanisms under different levels of mixed heavy metal stress.Results By measuring the germination rate, seedling height, and chlorophyll content of broad beans, we found that Cd-Zn-mixed stress has a synergistic inhibitory effect on the growth and development of broad beans. Cd and Zn can be transferred through the food chain, while broad beans can resist complex stress by regulating the content of total soluble sugars and photosynthetic pigments in the body, as well as accumulating proline. In addition, in the first generation of adult aphids, treatment with Cd (12.5 mg/kg) + Zn (100 mg/kg) significantly affected the expression of trehalase (TRE) and trehalose-6-phosphate synthase (TPS) genes and influenced the carbohydrate content and trehalase activity in the aphids.Discussion The number of offspring produced by the second-generation aphids was significantly reduced under mixed heavy metal treatment, but it was not caused by changes in the vitellogenin (Vg) content. These related results provide new avenues for further exploration of plant responses to mixed heavy metal stress, pest control, and management of heavy metal pollution.

The pervasive presence of microplastics has emerged as a pressing global environmental concern, posing threats to food security and human health upon infiltrating agricultural soils. These microplastics primarily originate from agricultural activities, including fertilizer inputs, compost-based soil remediation, irrigation, and atmospheric deposition. Their remarkable durability and resistance to biodegradation contribute to their persistent presence in the environment. Microplastics within agricultural soils have prompted concerns regarding their potential impacts on agricultural practices. Functioning as significant pollutants and carriers of micro- contaminants within agricultural ecosystems, microplastics and their accompanying contaminants represent ongoing challenges. Within these soil ecosystems, the fate and transportation of microplastics can detrimentally affect plant growth, microbial communities, and, subsequently, human health via the food chain. Specifically, microplastics interact with soil factors, impacting soil health and functionality. Their high adsorption capacity for hazardous microcontaminants exacerbates soil contamination, leading to increased adverse effects on organisms and human health. Due to their tiny size, microplastic debris is easily ingested by soil organisms and can transfer through the food chain, causing physiological and/or mechanical damage. Additionally, microplastics can affect plant growth and have the potential to accumulate and be transported within plants. Efforts to mitigate these impacts are crucial to safeguarding agricultural sustainability and environmental health. Future research should delve into the long-term impacts of environmental aging processes on microplastic debris within agricultural soil ecosystems from various sources, primarily focusing on food security and human beings.

Heavy metal (HM) poisoning of agricultural soils poses a serious risk to plant life, human health, and global food supply. When HM levels in agricultural soils get to dangerous levels, it harms crop health and yield. Chromium (Cr), arsenic (As), nickel (Ni), cadmium (Cd), lead (Pb), mercury (Hg), zinc (Zn), and copper (Cu) are the main heavy metals. The environment contains these metals in varying degrees, such as in soil, food, water, and even the air. These substances damage plants and alter soil characteristics, which lowers crop yield. Crop types, growing circumstances, elemental toxicity, developmental stage, soil physical and chemical properties, and the presence and bioavailability of heavy metals (HMs) in the soil solution are some of the factors affecting the amount of HM toxicity in crops. By interfering with the normal structure and function of cellular components, HMs can impede various metabolic and developmental processes. Humans are exposed to numerous serious diseases by consuming these affected plant products. Exposure to certain metals can harm the kidneys, brain, intestines, lungs, liver, and other organs of the human body. This review assesses (1) contamination of heavy metals in soils through different sources, like anthropogenic and natural; (2) the effect on microorganisms and the chemical and physical properties of soil; (3) the effect on plants as well as crop production; and (4) entering the food chain and associated hazards to human health. Lastly, we identified certain research gaps and suggested further study. If people want to feel safe in their surroundings, there needs to be stringent regulation of the release of heavy metals into the environment.