Introduction

The safety of local rice has a direct impact on residents’ health and well-being and is impacted by environmental conditions that impact levels of heavy metal pollution1,2,3. Globally, rice is the main staple food for more than half of the world’s population, with Asia, sub-Saharan Africa, and South America being the largest rice-consuming regions. According to the USDA’s September 2022 Global Grain Outlook report, 515 million tons of rice were produced worldwide in 2021 and 2022, while 518 million tons were consumed. It can be observed that the demand for rice is still greater than the output. Recently it has also been suggested that the issue of heavy metals in rice affects not only rice consumption but also rice will be made into rice vinegar, rice flour4. So the problem of heavy metal contamination of rice needs to be paid attention to.

One of the most publicized issues of rice quality is heavy metal contamination. The heavy metal elements in rice vary slightly depending on the geography of the country. Mercury (Hg), cadmium (Cd), and copper (Cu) are the most extensively researched major elements of heavy metal contamination in rice worldwide, with Hg being the most studied element in the Americas, Cd being the most studied element in China and India, and lead (Pb) being the most studied element in Western Europe and Australia5.

Scholar Yonghuan Ma reported that China’s per capita food production in 1949 was only 209 kg, which was still relatively low. Now, with the improvement in food production levels, China’s per capita food production has reached a high level, with 486 kg in 20226.

However, as the country’s development and industrialization have progressed, heavy metal pollution in rice has increased, posing a severe health risk. Heavy metal pollution loads are primarily influenced by factors such as soil properties, precipitation patterns, groundwater mobility, vegetation cover, and human activities7. According to Jiangdan Shi’s research, regions in China with high levels of heavy metals in rice are mainly heavily polluted areas such as mines and industrial zones, and children in these provinces are generally at higher risk of disease8. Scholar Qianqi Yang’s call for the country to identify Cd, Pb, and as priority control areas for heavy metals were similarly raised; mining areas were prioritized over other areas in industrial zones; food crop plantations were prioritized for control in agricultural zones9. Rong Zhang10 reported that cadmium contamination is mainly concentrated in southern regions such as Hunan, Zhejiang, and Guangxi. More districts and counties in Nanning have now planted rice on a large scale, and because of its high-quality water and good light, rice quality is better, but also famous. At the same time, Nanning is also rich in mineral resources. Therefore, ensuring proper control of the quality of rice in Nanning and detecting heavy metal contamination in rice is a priority that needs to be paid attention to. Scholar Yantao Huang11 also pointed out that the overall detection rates of Cd and Pb in Guangxi City in 2019–2022 were 96.4% and 62.1%. In 2018, the detection rates of lead, cadmium, inorganic arsenic, and total mercury in self-produced rice in Nanning City were all above 50%, and the total over-standard rate was 31.59%, especially the over-standard rate of cadmium was 29.60%12,13 a concerning situation regarding heavy metal pollution in rice planted in Nanning City, the capital of Guangxi.

Nowadays, there are technical differences between domestic and foreign scholars on the research of heavy metals in rice. Abroad, Sari14 has proposed using AI-based predictive models, specifically feed-forward artificial neural networks (ANN) with multilayer perceptron (MLP), to detect heavy metal levels in the environment, thereby significantly improving detection accuracy. Since rice is also one of the major staple foods in Malaysia, Syahirah Zulkaffee15, a Malaysian scholar, evaluated the content of heavy metals in paddy soils and their bioavailability in rice by vitro digestion model for health risk assessment. In China, rice heavy metal pollution detection mainly relies on electrochemical analysis, UV–VIS Spectrophotometry, Atomic spectrometry, and ICP-MS. Each method has its pros and cons: Atomic spectrometry offers rapid detection but struggles with insoluble and non-metallic elements, while ICP-MS, known for its high resolution and sensitivity, can be affected by complex sample components, potentially leading to errors16. Although the means of detecting heavy metals in rice are developing rapidly, the source analysis of heavy metal contamination in rice in China is still lacking.

For environmental analysis of heavy metal pollution, scholars globally employ common evaluation methods such as the single-factor evaluation method, Nemerow’s pollution index method, gray relation analysis, comprehensive pollution index method, and random forest evaluation method17. Single-factor analysis is often used in China because of its simplicity and ease of use18. The Nemerow Pollution Index method quantifies water quality and allows for a better understanding of the level of pollution in a water body19. The actual analysis can be carried out in a variety of analysis methods that can be combined to achieve better results. Lin20 integrated single-factor analysis with the Nemerow pollution index to analyze the main environmental impact factors of heavy metal pollution in fruit orchards.

This paper primarily analyzes the heavy metal pollution in the surrounding counties of Nanning City, with a focus on the heavy metal content in rice from Nanning City. By employing GIS (Geographic Information System) technology, we visualize the pollution distribution, conduct spatial statistical analysis, and assess the spatial variability. Furthermore, additional environmental factors, such as soil and irrigation water for rice cultivation, were assessed to analyze the correlation between heavy metal content in the soil, the quality of irrigation water, and rice contaminated by heavy metals. This study aims to provide early warning of potential risks associated with local rice cultivation and offer a theoretical and data basis for the development of control and management policies.

Methods

Sample source

The samples come from 605 locally grown rice (including farmers’ self-produced rice and locally produced rice sold in farmers’ markets, supermarkets, and other markets) in 5 counties and 7 districts (including development zones) of Nanning in 2019. 205 soils corresponding to the rice planting area and 185 water samples from irrigation sources in the same area.

Sampling method

  1. 1.

    Rice samples: Five administrative villages and towns are selected from each county (district), and Poisson distribution points are adopted in the East, South, West, North, and middle according to the regional distribution; 20% of natural villages are randomly selected from each township, and the sample number of each village is evenly distributed.

  2. 2.

    Soil samples: Soil samples were collected from the planting site of the farmer who collected the rice. About 100 cm2 of soil was collected on the soil surface at a depth of 0–20 cm, and 4–5 small samples were taken in a plum shape. The soil that did not come into contact with the shovel was dialled into the plastic film with the main shovel and mixed thoroughly, with approximately 200 g retained as a sample using the quadrature method and numbered in a plastic bag while the GPS coordinates were recorded. Soil and rice (paddy) samples must correspond to each other.

  3. 3.

    Irrigation water samples: Irrigation water samples are collected from irrigation water sources at or near the farmers’ planting sites where rice is collected. Refer to NY/T396-2000 “Technical Specification for Monitoring Environmental Quality of Agricultural Water Sources” to take samples 1–2 times during the main irrigation period. When collecting transient samples, first wash the sampling bottle and stopper with water samples 2 –3 times without stirring the sediment at the bottom during sampling. Collected samples with nitric acid to PH < 2, labelling needs to be noted rice samples corresponding number, labelling and sent to the test. Water samples and rice (paddy) samples must be one-to-one correspondence.

Evaluation methods for samples

Rice samples are evaluated by the National Food Safety Standard Maximum Levels of Contaminants in Foods (GB2762-2017). The rice could be seen as a nonconforming sample if it has more than unqualified monitoring items.

The criteria for those no heavy metal pollution detected are as follows: lead < 0.050 mg/kg, cadmium < 0.0030 mg/kg, inorganic arsenic < 0.050 mg/kg, total mercury < 0.010 mg/kg. The criteria for exceeding standards are evaluated according to the National Food Safety Standard Maximum Levels of Contaminants in Foods (GB2762-2017). The rice will be classified as superscalar if the concentration of lead, cadmium, and inorganic arsenic is greater than 0.2mg/kg and the concentration of total mercury is greater than 0.02mg/kg. The sample would be judged as unqualified if it has one more than nonconforming monitoring items.

The Single-factor pollution index21 and Nemerow composite pollution indices (Table 1)22 are used to evaluate whether heavy metals contaminate the crops.

Table 1 The evaluation standard of the Nemerow pollution index.
Full size table
  1. 1.

    The formula of s Single factor pollution index is:

$${\text{Pi}} = \frac{{C_{i} }}{{S_{i} }}$$
(1)

In this formula:

  • Pi is the pollution index of heavy metal I in crops.

  • Ci is the measured mass concentration of heavy metal I in crops.

  • Si is the limit standard of heavy metal I in crops.

When Pi > 1, it shows that crops are polluted by heavy metal I; When Pi < 1, it shows crops are not polluted by heavy metal I;

  1. 2.

    The formula of Nemerow complex pollution indices is:

$${\text{P}}_{{\text{N}}} = \sqrt {\frac{{P_{{i{ }ave}}^{2} + P_{{i{ }max}}^{2} }}{2}}$$
(2)

In this formula:

  • PN is the Nemerow complex pollution indices method.

  • Pi Ave is the average individual pollution index.

  • Pi max is the maximum of an individual pollution index.

The limit standard of heavy metals in the soil refers to the Soil environmental quality Risk control standard for soil contamination of agricultural land (GB15618-2018) (Table 2).

Table 2 Standard values of soil environmental quality/(mg/kg).
Full size table

The survey collects the soil of rice fields and vegetable fields, which need to be regarded with secondary standards. The water quality for farmland irrigation is assessed and evaluated according to the Irrigation Water Quality Standard (GB5084-2005).

Experimental methods and procedures

  1. 1.

    Determination of total arsenic, cadmium, and lead: inductively coupled plasma mass spectrometry (ICP-MS).

After the rice and paddy were powdered and sieved, 0.5 g (accurate to 0.001 g) was accurately weighed in a microwave digestion tank and added with 8mL of nitric acid, then placed on a microwave digestion pre-treatment heater at 100 °C for 1 h, and then placed on a microwave digestion instrument to carry out the digestion by the set program. After cooling, take out the inner tank, put it on the microwave pre-treatment heater at 140 °C to drive the acid to dryness, and then volume it to 10 mL with water, which was detected by ICP-MS. The Blank test was done at the same time. The limits of detection for total arsenic, cadmium, and lead were 0.0040 mg/kg, 0.0030 mg/kg, and 0.0040 mg/kg, respectively.

  1. 2.

    Determination of mercury: direct mercuric meter method (mercuric meter).

After the rice and paddy have been powdered and sieved, accurately weigh 0.1 g (accurate to 0.001 g) of uniform samples in a sample boat and put them directly into the DMA-80 (Direct Mercury Meter) for testing. Do the blank test at the same time. The detection limit of mercury was 0.0050 mg/kg.

  1. 3.

    Determination of inorganic arsenic: liquid chromatography-atomic fluorescence spectrometry (LC-AFS).

According to GB 2762-2017, the limit for inorganic arsenic (As) in paddy and rice is 0.2 mg/kg. The inorganic arsenic limit of the food can be determined first for the total arsenic, and there is no need to determine the inorganic arsenic when the level of total arsenic does not exceed the value of the inorganic arsenic limit. Or else we need to determine the inorganic arsenic again. After rice and paddy are powdered and sieved, accurately weigh 1.0 g (accurate to 0.001 g) of the sample, place it in a 10mL polypropylene centrifuge tube, add 10 mL of 0.15 moLL nitric acid solution, and seal it tightly. The sample was extracted at 90 °C for 2.5 h, shaking every half hour for 1 min. After extraction, the sample was cooled down to room temperature, centrifuged at 8000 r/min for 15 min, and the upper layer of the clear night was filtered through a 0.45 µm organic filter membrane and then injected into the sample. The blank test is proceeded at the same time. The method detection limit of inorganic arsenic is 0.50 mg/kg.

  1. 4.

    Quality control.

The blank test proceeds at the same time during the above experiments, parallel sample testing (10%), over the standard sample review, quality control sample testing, spiked recovery, and other experiments are conducted for quality control.

Data statistical analysis

Excel 2010 software is used for processing input data to calculate the over-standard rate of heavy metal elements in rice and corresponding regional soil and irrigation water. The statistical correlation analysis and chi-square test was conducted using SPSS 17.0. The difference was statistically significant when P < 0.05. The distribution maps of cadmium, lead, mercury, inorganic arsenic, and other metal contents were drawn using ArcGIS software (Fig. 1).

Fig. 1
figure 1

Flowchart of environmental impact assessment.

Full size image

Results and analysis

Heavy metal contamination in rice

A total of 605 rice samples were collected from various sources, including supermarkets, farmers’ markets, retail stores, school cafeterias, and farmers’ homes (Tables 3, 4). Out of these, 142 samples exceeded the standard values, resulting in an overall exceedance rate of 23.7%. Specifically, the exceedance rates for cadmium, inorganic arsenic, lead, and total mercury were 14.71%, 5.62%, 2.64%, and 0.66%, respectively. Additionally, the average concentration of the nutrient zinc in rice was (15.71 ± 3.55) mg/kg, and the median concentration of selenium was 0.004 mg/kg. The comprehensive pollution index (PN) for heavy metals selenium, cadmium, total mercury, and inorganic arsenic in rice was 0.712, indicating a level of cleanliness.

Table 3 Excessive heavy metals in locally grown rice.
Full size table
Table 4 Excessive heavy metals in locally grown rice.
Full size table

Soil heavy metal contamination

A total of 205 soil samples were collected from 10 to 40 sampling points in each area (Table 5). The soil in the rice-growing areas of Nanning City is generally acidic, conforming to GB15618-2018. Except for the soil heavy metal contents in Long’an, Shanglin, and Mashan counties, which were higher than the corresponding risk screening values, the other heavy metal contents were below the agricultural land soil pollution risk screening values (Tables 5, 6). This suggests a low risk to the quality and safety of agricultural products, crop growth, and the soil ecological environment.

Table 5 Heavy metal content in the soil in the rice planting areas of all counties (districts) in Nanning city.
Full size table
Table 6 Total content of heavy metals in the soil in rice growing areas in Nanning /(mg/kg).
Full size table
Table 7 Heavy metal content in irrigation water in all counties (districts) of Nanning city (mg * 10–3/kg).
Full size table

Heavy metal contamination in irrigation water

The detection values of heavy metals in the irrigation water of the rice-growing areas were below the agricultural land irrigation water pollution risk screening values for the corresponding PH values, with most being below the detection limit (Table 7). This indicates that the irrigation water is safe for the quality of rice in the respective areas, with an extremely low environmental risk impact.

Table 8 Correlation of heavy metal content in rice with soil and irrigation water.
Full size table

Correlation analysis of heavy metal content in rice, soil, and irrigation water

The correlation coefficients (r) between different heavy metal elements in rice and soil, as well as between rice and irrigation water, are presented in (Table 8). The coefficients for inorganic arsenic, lead, cadmium, total mercury, and selenium content in rice and the corresponding heavy metal content in soil and irrigation water were all below 0.4, indicating a low correlation. This suggests that the risks to rice safety and quality due to environmental factors in the Nanning area are relatively small and within a controllable risk range.

Spatial autocorrelation analyses

In Nanning, the primary heavy metal pollutants include cadmium, lead, and inorganic arsenic. In Wuming District, the exceedance rate of certain heavy metals is high, and inorganic arsenic pollution is also observed in Mashan County (Figs. 2, 3, 4). To further analyze the heavy metal pollution in rice in Nanning City, the Moran’s index was used as an analytical tool. The Moran’s I index, ranging from – 1 to 1, was used, where values greater than 0 indicate positive spatial correlation, with values closer to 1 suggesting stronger spatial aggregation, and values around 0 indicate negative correlation, with values closer to – 1 indicating greater spatial dispersion. Spatial correlations were represented with three colors: red for high-high (hot spots), blue for low-low (cold spots), and green for high-low.

Fig. 2
figure 2

Distribution of exceedance rate of cadmium in locally grown rice in Nanning, China. Figure generated by the authors using ArcGIS ArcMap 10.5 (https://www.esri.com/en-us/contact#c=cn&t=3).

Full size image
Fig. 3
figure 3

Distribution of exceedance rate of Lead in locally grown rice in Nanning, China. Figure generated by the authors using ArcGIS ArcMap 10.5 (https://www.esri.com/en-us/contact#c=cn&t=3).

Full size image
Fig. 4
figure 4

Distribution of exceedance rate of inorganic arsenic in locally grown rice in Nanning, China.Figure generated by the authors using ArcGIS ArcMap 10.5 (https://www.esri.com/en-us/contact#c=cn&t=3).

Full size image

The Moran’s I index values for cadmium (0.27), inorganic arsenic (0.45), and lead (0.47) in each administrative district of Nanning indicate spatial correlation, with cold hotspot analysis and scatter distribution maps shown in Figs. 5, 6 and 7.

Fig. 5
figure 5

Moran’s I index and clustering of Cd in locally grown rice in Nanning, China. Figure generated by the authors using ArcGIS ArcMap 10.5 (https://www.esri.com/en-us/contact#c=cn&t=3).

Full size image
Fig. 6
figure 6

Moran’s I index and clustering of lead in locally grown rice in Nanning, China. Figure generated by the authors using ArcGIS ArcMap 10.5 (https://www.esri.com/en-us/contact#c=cn&t=3).

Full size image
Fig. 7
figure 7

Moran’s I index and clustering of inorganic arsenic in locally grown rice in Nanning, China. Figure generated by the authors using ArcGIS ArcMap 10.5 (https://www.esri.com/en-us/contact#c=cn&t=3).

Full size image

ArcGIS was utilized to identify specific locations with spatial clustering of high and low values of heavy metal pollution. Overall, significant heavy metal pollution features were observed in Shanglin County, Yongning District, and Jiangnan District. Hotspot areas for cadmium and lead were found in Shanglin County, while Yongning District was a coldspot area for cadmium, and the spatial correlation of inorganic arsenic was not significant. This suggests spatial clustering of high and low values, indicating that most rice samples collected in Shanglin County were affected by Cd and Pb.

From these results, it can be concluded that the comprehensive pollution index (PN) for heavy metal pollution in rice is 0.712, which is considered clean. Additionally, the correlation between heavy metal content in rice and the corresponding regional soil and irrigation water heavy metal content is low (less than 0.4), suggesting that the overall impact is within a controllable risk range. However, despite the clean level of the heavy metal contamination index, the presence of heavy metal contamination in rice cannot be ignored, and the cumulative effect of trace amounts of heavy metals remains a dietary health risk factor.

Discussion

The total heavy metal contamination rate of rice samples grown in 12 counties in Nanning City reached 23.30%. Among them, cadmium pollution was the most serious, with the highest detection value of 1.28mg/kg, and the exceedance rate reached 14.71%; other heavy metals, such as inorganic arsenic. The exceedance rates of lead and total mercury were 5.62%, 2.64%, and 0.66% respectively. The comprehensive pollution index of heavy metals lead, cadmium, total mercury, and inorganic arsenic in rice is 0.712, which belongs to Level II and is still clean. Comparing the investigation results of heavy metal pollution in rice in other provinces and cities, rice in Nanning City has high cadmium pollution.

The spatial distribution of heavy metal pollution was delineated using Moran’s index and cold hot spot analysis, revealing patterns of spatial agglomeration. The main manifestations are H–H (high–high), L–L (low–low), and H–L (high–low) agglomeration. Combined with the analysis of cold and hot spots, the hot spots were mainly concentrated in the surrounding areas. Taking cadmium heavy metal pollution as an example, Long’an County, Mashan County, and Shanglin County in the neighbouring districts and counties of Nanning City are all located in the north-western part of Nanning City and are close to the mineral resource-rich areas of Hechi and Baise City, which will be affected by neighbouring veins of mines and lead to an increase in the content of heavy metals in the soil and water sources.

For the pollution in Wuming County in the central part of Nanning City, it is taken into account that the vigorous development of tropical fruit cultivation, along with a large number of improper use of pesticides, can cause acidification of the soil, leading to the aggregation of heavy metals in the soil. In 2002, the Rice and Products Quality Supervision, Inspection and Testing Center of the Ministry of Agriculture conducted random inspections on the safety of rice in the national market. The results showed that the most serious heavy metal exceeding the standard in rice was lead, with an exceeding rate of 28.4%, followed by cadmium, with an exceeding rate of 10.3%. Professor Pan Genxing from the Institute of Agricultural Resources and Ecological Environment of Nanjing Agricultural University, along with his research team, procured approximately 10% of 91 rice samples from markets above the county level across six regions nationwide, revealing that commercially available rice contains excessive levels of cadmium23,24. In recent years, all provinces and cities across the country, particularly those that are rice-producing, have attached great importance to heavy metal pollution and implemented relevant research and improvement policies.

Nanning City, Guangxi is located in the subtropical zone and is rich in mineral resources. 63 types of mineral resources have been discovered. Nanning’s heavy metal-related enterprises are mainly non-ferrous metal mining, non-ferrous metal smelting, tanning, electroplating, chemical raw materials, chemical products industries. 5 industries. During the rapid industrial and agricultural development, there has been a concomitant rise in population, sewage discharge, and water pollutant emissions. This surge leads to an increased risk of contamination in agricultural soils and irrigation waters. The “three wastes”—waste gas, liquid, and solid—emitted by these industries can significantly pollute the environment and jeopardize ecological security if not managed within the prescribed emission standards. These industrial by-products contain numerous toxic and harmful substances that, when released into the environment without adhering to the required standards, can overwhelm the environment’s self-purification capacity, leading to ecological imbalance25. Mineral cadmium pollution in Guangxi has been proposed to be associated with liver function in the population26.

At the same time, the irrational use of agricultural products and excessive use of chemical fertilizers and pesticides not only cause non-point source pollution in rural areas but also contaminate farmland soil and irrigation water. Through the investigation and rectification of heavy metal enterprises during the “12th Five-Year Plan” and the “13th Five-Year Plan”, as well as the investigation and treatment of soil pollution in agricultural land, most of the cultivated land is of good quality, and the proportion of areas with excessive heavy metals in the total cultivated land is not large. The excessive heavy metals in farmland soil are primarily caused by high soil background values, followed by pollution from industrial and mining enterprises.

The overall soil environmental quality in Nanning City is in good condition. The farmland is generally clean or still clean. The soil is mostly acidic and the soil pollution is distributed in the area. Uneven. From the perspective of administrative divisions, the order of soil environmental quality pollution from heavy to light is Mashan County > Long’an County > Shanglin County > Binyang County > Heng County > Former Wuming County (Wuming District) > Other urban areas the main pollution areas are Mashan County (moderate pollution), Long’an County (light pollution), and Shanglin County (light pollution). This is consistent with the monitoring results in this article, indicating that attention should be paid to the environmental pollution in this part of the area. There are heavy metal pollution control issues. However, it can be seen from the conclusion that the risk of soil heavy metal pollution in Nanning City is relatively small.

Within ecosystems, water, soil, air, and organisms are interconnected, facilitating the transfer of pollutants among different media27. Industrial waste, sewage irrigation, and agricultural non-point source pollution are three-dimensionally related to soil pollution and excessive heavy metals28. The quality of any surface or underground body is the result of a combination of natural and human activities. In addition to the impact of human activities, the quality of water depends on the weathering of bedrock minerals, evapotranspiration, atmospheric processes that deposit dust and salt brought by wind, the natural leaching of soil organic matter and soil nutrients, and the resulting runoff Hydrological factors and biological processes present in the aquatic environment that can modify the physical and chemical composition of water. Major water contaminants include microorganisms, nutrients, heavy metals, organic chemicals, petroleum, and sediments. The largest sources of water pollution are the lack of adequate treatment of human waste and improper management and treatment of industrial and agricultural waste29,30. Generally, heavy metal pollution in soil caused by increased sewage irrigation and its duration has become the most serious pollution problem in farmland. Imperfect infrastructure construction in townships and towns, direct discharge of untreated domestic sewage, and chemical fertilizers, pesticides, agricultural films, growth Rural non-point source pollution caused by the unscientific use and disposal of agricultural materials such as conditioners has brought harm and risks to rural surface water, groundwater and other irrigation water needed for rice growth31,]32. The low levels of heavy metal pollution in Nanning City’s rice irrigation water indicate effective government controls on agricultural pollution and targeted inspections of heavy metal industries. Consequently, rice contamination risks are minimized.

Although the present study shows that environmental concentrations of heavy metals are at clean levels and within manageable limits and the impact of risks caused by environmental factors on the safety and quality of rice in Nanning is relatively small, heavy metal pollution is continuously enriched through the food chain and reaches very high concentrations in the human body, will cause health hazards to the human body33. Therefore, by effectively exploring the environmental factors that lead to heavy metal pollution in local rice, we can increase the attention of local governments in rice-producing areas to food safety and then take effective measures to improve local ecology, agriculture, forestry, irrigation and other technical levels, and improve rice (rice) and even other agricultural products. The safety and nutritional value of side-line products have great social benefits and economic prospects.

Conclusions

Examining the heavy metal content in rice and heavy metal content in soil and water in the environment, the results showed that the total exceedance rate of heavy metals in local rice was 20.95%, and that of paddy rice was 33.33%. The exceedance rates of lead, cadmium, inorganic arsenic, and total mercury in rice were 2.23%, 17.88%, 0.56%, and 0.84%, respectively. And cadmium was screened as the main pollution factor of local rice with the highest detection value of 1.23 mg/kg, which is 6.15 times higher than the national health standard. Although the analysis concluded that environmental factors have less influence on the heavy metal contamination of rice, it is equally important to draw attention to it. Therefore, our government and organizations can improve the occurrence of heavy metal contamination of rice in Nanning by considering the improvement of local environmental heavy metal detection technology and crop inspection standards, and relevant departments should regularly inspect the areas with a high incidence of heavy metal contamination, to better ensure the safety of rice and other crops in southwest China, and thus ensure the safety of residents’ diets.