Thiamethoxam and clothianidin residues on spinach after spraying
What it found
After spinach was sprayed with thiamethoxam, the pesticide broke down quickly, with half gone in 1.6 days or less, and the amounts left on the leaves were below China's residue limits.
The authors calculated that the short-term dietary risk to Chinese consumers was low.
What they found
Studies in people
Short-term dietary risk
The authors calculated that the short-term dietary risk from eating spinach with these residues was low for all consumer groups in China. Risk values were all below 100%, and children had higher values than adults.
Other findings
Breakdown on spinach
Thiamethoxam broke down quickly on spinach, following first-order kinetics, with half-lives of 1.3 to 1.6 days at three sites. At a fourth site, 97% was gone after 3 days and levels fell below the limit of quantitation after 5 days.
Clothianidin formation
Clothianidin, a breakdown product of thiamethoxam, appeared quickly and reached its highest levels 3 to 5 days after spraying. At most sites, clothianidin residue was higher than the parent thiamethoxam.
Temperature and light
Higher temperature and more light led to faster breakdown of thiamethoxam. The authors say these were the two main factors affecting how long the pesticide stayed on the spinach.
Residues at harvest
At 8 sites, the average residues of thiamethoxam and clothianidin on spinach were below China's maximum residue limits. The highest residues found were 0.41 mg/kg for thiamethoxam and 0.52 mg/kg for clothianidin.
What the authors conclude
“The values of RQ a % values were far less than 100%, indicating that no significant risk on human health was posed at the recommended dose.”
Also in their conclusions
- They conclude that the acute dietary risk to different consumer groups in China was far below 100%, indicating no significant risk to human health at the recommended dose.
- They say this work provides valuable guidance on the safe and proper application of thiamethoxam for spinach grown in field conditions.
How it was done
Thiamethoxam is sprayed directly on the edible leaves of spinach, and spinach is harvested soon after. The authors wanted to check how much pesticide and its breakdown product clothianidin remain on spinach, and whether that could pose a short-term risk to consumers.
They sprayed spinach once with thiamethoxam at the recommended highest dose of 27 g active ingredient per hectare at 8 field sites in China. They collected leaf samples from 2 hours up to 10 days after spraying and measured thiamethoxam and clothianidin levels using a lab method. They then used these residue levels to calculate short-term dietary intake for different age groups in China.
What it can’t tell you
- This study measured residues on spinach and calculated dietary intake. It did not give the spinach to people or test health effects.
- The risk assessment is based on residue levels and food intake data, not on actual health outcomes in consumers.
Who paid
- Funding
- Funded by Key Research and Development Program of Shanxi Province in China (from the PubMed record).
- Conflicts
- The authors declare no conflict of interest.
- Authors work at
- Shanxi Agricultural University, China
The paper
- Title
- Dissipation Behavior and Acute Dietary Risk Assessment of Thiamethoxam and Its Metabolite Clothianidin on Spinach
- Type
- Study
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Yang Y, Qin S, Wang X, Cao J, Li J (2022). Dissipation Behavior and Acute Dietary Risk Assessment of Thiamethoxam and Its Metabolite Clothianidin on Spinach. Molecules (Basel, Switzerland). doi:10.3390/molecules27072209Free full textPubMed 35408608DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error