Pesticide Residue Limits Raised 24-Fold: Is It Still Safe to Eat Chinese Chives?
Effective from 11 May this year, a revised national food safety standard officially came into force. The maximum residue limit for procymidone in chives has been raised from 0.2 mg/kg to 5 mg/kg – a twenty-fourfold relaxation.
But is this actually the case?
I. A Relatively High Acceptable Daily Intake
The EU, which does not permit prochloraz products, sets its ADI at 0.0028 mg per kilogram of body weight daily, merely 2.8% of China’s standard.
Even in countries that permit agricultural use of prochloraz, their ADI limits are significantly lower than the new national standard. For instance, Australia sets the ADI for prochloraz at 0.05 mg per kilogram of body weight daily, exactly half of China’s standard; Japan’s ADI is 0.038 mg per kilogram of body weight daily, merely 38% of China’s.
ADIs are typically derived from animal studies by dividing the experimentally proven harmful dose by a fixed safety factor, to ensure safety across all population groups. The standards in the aforementioned countries have largely been revised in light of more recent toxicological research. China’s comparatively high ADI value may simply reflect a lack of similar updates drawing on newer toxicological data.
II. Ubiquitous Prochloraz
But does it logically follow that because chive consumption is low, the risks associated with pesticide residues can simply be relaxed?
As a broad-spectrum fungicide, procymidone is currently widely employed in disease management across a variety of fruits and vegetables. Under national regulations, procymidone residue limits for different fruits and vegetables range between 2 and 10mg/kg. Therefore, we must account for the cumulative intake from all these sources combined.
In their 2019 paper, *Detection of Procymidone Residues in Leeks and Assessment of Long-term Dietary Exposure*, Zhou Yong and colleagues calculated the National Estimated Daily Intake (NEDI) of procymidone at 2.5562 mg, deriving this figure from residue levels across various foodstuffs and average daily consumption patterns among Chinese residents.
This equates to 40.6% of the maximum daily intake for an average adult weighing 63 kg who consumes 275 g of vegetables and 45 g of fruit daily. Yet, as living standards continue to rise, the total volume of fruit and vegetables consumed by many individuals is very likely already surpassing this benchmark.
The *Chinese Dietary Guidelines (2022)* recommend a daily intake of 300–500 g of vegetables (half of which should be dark-coloured) and 200–350 g of fruit per person. If an average-weight individual were to consume at the upper end of these recommendations—500 g of vegetables and 350 g of fruit daily—the calculated intake would rise to 7.089 mg. This represents 113% of the maximum daily intake, a rather substantial figure.
III. Procymidone and Grey Mould on Chinese Chives
According to data compiled by the non-profit organisation Natural Field, even if the maximum residue limit for procymidone is raised to 5mg/kg, a substantial number of tested samples would still exceed the threshold.
Their review of regulatory records across 15 provinces and municipalities nationwide in 2022 revealed 223 instances where procymidone levels in chives breached the original limits. Even after adjusting the limit to 5mg/kg, 31 instances would still be in violation. The highest recorded residue level reached 35.5mg/kg, which is seven times the new national standard.
Why do procymidone residues in Chinese chives remain so stubbornly high? To understand this, we must look at the production end.
Procymidone is primarily applied in Chinese chive cultivation to prevent and control grey mould. In 1985, Li Mingyuan and Liu Jie at the Beijing Plant Protection Station were the first to identify the pathogen responsible for this disease within China. They also observed that the fungus thrives at temperatures between 15°C and 20°C under conditions of high humidity. When infection sets in, the leaves typically develop dried tips or white patches; in severe cases, grey fungal growth emerges, or the entire leaf may wither and die.
As early as 1985, Li Mingyuan and his colleagues observed that grey mould was the primary affliction for chives grown under plastic film for winter and spring insulation. With the subsequent proliferation of greenhouses and solar tunnels, these poorly ventilated, high-humidity structures have frequently become breeding grounds for the disease.
A five-year field survey by grassroots agricultural technicians in a region of Henan province found that grey mould is more severe in chives cultivated in solar greenhouses than in plastic tunnels; within plastic tunnels, infections are worse in low tunnels than in high ones; whereas open-field chives exhibit a comparatively low infection rate.
IV. How to prevent and control grey mould?
While these practices may bolster plant vigour or improve growing conditions, the ongoing expansion of large-scale contiguous cultivation and protected structures means that rising grey mould incidence is an inescapable trend unless farming methods are actively adjusted to promote plant health. As a result, applying fungicides after an outbreak has become standard practice for most growers.
The recommended pre-harvest interval for the most widely used fenpiclonil fumigants and wettable powders is 30 days, mirroring the protocol used in trials. However, a standard growing cycle for Chinese chives is also roughly 30 days. This means the fungicide can only be applied once per crop, and must be done immediately after the previous harvest.
It is highly unlikely that growers would follow this approach. Take the use of fenpiclonil fumigants in greenhouses, for example. During winter and spring, the routine practice is often to apply them preventatively every seven days. This is because, once an outbreak occurs, the disease becomes extremely difficult to contain. Yet growers rarely wait for the safety interval to lapse before harvesting; waiting too long causes the chives to toughen and lose their market value.
Decades of continuous fenpiclonil application have gradually bred resistance in grey mould, diminishing the chemical’s efficacy and forcing producers to compensate with heavier doses.
In 2022, Hu Bin and colleagues tested nine different fungicides on *Botrytis* strains isolated from Chinese chives in Shandong. Their findings revealed that the strains exhibited the highest resistance to fenpiclonil, rendering it significantly less effective than several alternative fungicides.
V. From “Strictest Supervision” to “Most Rigorous Standards”?
In most of these cases, the violation stems from fenpiclonil residues exceeding legal limits.
With the maximum residue limit for procymidone in chives relaxed by a factor of 24, news of this nature will inevitably become rarer. However, the inherent safety of the crop remains unchanged, and the long-term overuse of low-toxicity pesticides such as procymidone continues to pose uncertain risks.
On a macro level, chemical applications have lowered production barriers, enabled greenhouse farming to maintain year-round supply, and helped large-scale operations combat crop diseases. While these continuous, large-scale production models are undoubtedly better suited to market demands, they have also triggered a counterproductive reliance on agrochemicals. This explains why, despite two millennia of chive cultivation in China, one can now hear farmers claim that “you cannot grow crops without chemicals”.
We fear that with pesticides acting as a safety net, fewer and fewer producers will prioritise ecologically friendly, plant-health-supporting cultivation methods. Ultimately, threatened by growing resistance, they will be forced to continuously increase chemical applications until they cease to be effective.
At its core, the key to resolving the pesticide residue issue remains addressing the overuse of chemicals in production, a problem by no means confined to chives. Meanwhile, the fact that regulators cannot reach producers has created a long-standing contradiction between regulatory frameworks and the over-reliance on chemicals in farming. The moniker “toxic chives” has gained notoriety not merely because the crop has a history of exceeding limits, but because this systemic contradiction brought the issue to light. Harsh penalties subsequently amplified it, making it a matter of public concern.
While revising these “most rigorous standards” may help alleviate the tension, it will not alter the fundamental realities of agriculture. It also sends a clear message to the public: safeguarding food safety depends less on stringent market oversight and more on fundamentally transforming unsustainable agricultural practices.
Zhou Yong, Pak Soo-young, Liao Xianjun, Liu Jia, Zhu Hang, Ma Haihao, Zhou Xiaomao, Li Fugen. Residue Detection of Procymidone in Chives and Assessment of Long-term Dietary Exposure[J]. Journal of Pesticide Science, 2021, 23(2): 373-379.
[Briefing on the Quality and Safety of Agricultural Products, Issue 5] Summary Analysis of Non-compliant Results from Market Regulation Sampling of Edible Agricultural Products in 2020 http://www.jgs.moa.gov.cn/gzjb/202102/t20210218_6361714.htm
Residue Detection of Procymidone in Chives and Assessment of Long-term Dietary Exposure. Liu Yuhong.
Hu Bin, Huang Zhongqiao, Liu Xili, et al. Efficacy of Nine Fungicides in Controlling Botrytis Leaf Blight in Chives[J]. Chinese Agricultural Science Bulletin, 2014, 30(4):6.
Liu S, Che Z, Chen G. Multiple-fungicide resistance to carbendazim, diethofencarb, procymidone, and pyrimethanil in field isolates of Botrytis cinerea from tomato in Henan Province, China[J]. Crop Protection, 2016, 84: 56-61.
Xing Yanwei. Occurrence and Integrated Management of Botrytis Leaf Blight in Chives[J]. Friends of Farmers’ Wealth, 2014, No. 495(22):95.
Reconsideration of Procymidone: Human health risk assessment report (including Toxicology and Work Health Safety), Australian Pesticides and Veterinary Medicines Authority, 2017
GHS Classification Results by the Japanese Government
Editor: Ze’en