Monitoring dithiocarbamate fungicide residues in greenhouse and non-greenhouse tomatoes in Iran by HPLC-UV

Development of a novel HPLC-CDCL method utilizing nitrogen-doped carbon dots for sensitive and selective detection of dithiocarbamate pesticides in tea

In this study, S-methyl derivatives of dithiocarbamates (DTCs) were shown to significantly enhance chemiluminescence (CL) between Ce(IV) and efficient and environmentally friendly nitrogen-doped carbon dots (NCDs). Based on the elucidation of the CL mechanisms, an innovative approach involving high-performance liquid chromatography coupled with N-CDs and CL detection (HPLC-CDCL) was proposed. The developed method was successfully applied to the highly sensitive detection of three DTC fungicides (dimethyl dithiocarbamate, ethylene bisdithiocarbamate, and propylene bisdithiocarbamate) in tea. The recovery of the established method ranged 70.51-116.45%, with relative standard deviations (RSD) of <9.40%. The limit of detection (S/N = 3) was as low as 0.19 μg/L (as CS2), which is superior to the previous methods and comparable to UPLC-tandem mass spectrometry (MS/MS). Moreover, the proposed approach does not require solid-phase extraction and offers excellent selectivity. This study proposes a novel method for the detection of DTCs in the food safety and environmental fields.

Thiamethoxam dynamics in pepper plants: Deciphering deposition and dissipation pattern across diverse planting modes and regions

To reduce the application dosage of thiamethoxam (TMX), we investigated the deposition and dissipation patterns in a pepper-planted ecosystem under different planting modes across four regions in China, namely Hainan (HN), Zhejiang (ZJ), Anhui (AH) and Hebei (HB). This study focused on the deposition and dissipation of TMX at concentrations of 63.00, 47.25, 31.50, 23.63 and 15.75 g a.i.hm-2. As the application dose increased, the deposition amount of TMX initially increased in the plants and cultivated soil, showing obvious geographic differences in four cultivation areas. Surprisingly, the initial amount of TMX deposited the pepper-cultivated greenhouse of ZJ and AH was 1.1-2.1-fold and 1.0-3.6-fold higher than that in the open field system at the same application dose, respectively. In pepper leaves, stems, fruits and soil, the dissipation exhibited rapid growth and then slowed. However, the residual concentration showed an increasing trend, followed by a subsequent decrease in the pepper roots. In different planting regions, the dissipation rate of TMX followed the order HN > ZJ > AH > HB in pepper plants and cultivated soil. In comparison to the open field, the total TMX retention rate in greenhouse was higher, indicating overall greater persistence in the greenhouse conditions. These findings reveal the deposition and dissipation characteristics of TMX within the pepper-field ecosystem, offering a significant contribution to the risk assessment of pesticides.

Occurrence and risk characterization of aflatoxin M1 in milk samples from southeastern Iran using the margin of exposure approach

This study aimed to investigate Aflatoxin-M1 (AFM1) contamination in pasteurized and raw milk samples consumed in Kerman and Rafsanjan in southeastern Iran. In this cross-sectional study, a total of 100 samples of raw (n = 67) and pasteurized (n = 33) milk were randomly collected from retail stores, supermarkets, and milk transport tankers in the winter of 2020 and the summer of 2021. The level of AFM1 contamination in the collected samples was evaluated by high-performance liquid chromatography with fluorescence detection (HPLC-FD). AFM1 was detected in 95% of samples and its median concentration was 17.38 ng/L. The median concentration of AFM1 in the pasteurized milk samples (24.89 ng/L) was significantly higher than in the raw milk samples (13.54 ng/L). The AFM1 contamination level in 20% (raw = 13% and pasteurized = 7%) of the samples was higher than the maximum permitted level (MPL) recommended by the European Union (i.e., 50 ng/L), whilst 4% (raw = 3% and pasteurized = 1%) of the samples was higher than the Iranian maximum standard limit (i.e., 100 ng/L). The hazard index (HI) was higher than 1 in 16%, 18%, and 35% of total milk samples for men, women, and children, respectively. The AFM1 contamination level in the milk samples collected in southeastern Iran was worrying. The margin of exposure (MoE) values were lower than 10,000 for children. Because aflatoxins are among the most potent carcinogens known, prevention of milk contamination in all stages from the farm to the table can considerably reduce the community's exposure to AFM1 and its consequent health risks.

Dithiocarbamates: Properties, Methodological Approaches and Challenges to Their Control

Dithiocarbamates (DTCs) are a group of chemicals used primarily as fungicides, although they are exploited for various other applications. DTCs represent one of the oldest classes of broad-spectrum fungicides employed worldwide to control fungal diseases on many crops. Due to their ease of synthesis, low production costs (cheap and readily available starting materials) and a fungicidal activity with a multi-site mode of action, they are still among modern agriculture's most extensively used pesticides. Although the environmental degradation in air, water, and soil is relatively rapid due to photolysis and/or hydrolysis, they are among the most frequently detected pesticides in the European Union (EU), also with a high frequency of maximum residue level (MRL) exceedances. The current review aims to comprehensively survey all aspects of DTCs, including the environmental fate, toxicity and analytical methods for determining parental compounds and degradation products in environmental and food samples. Furthermore, the accumulation of carbamate and dithiocarbamate pesticides in vegetables, fruits, bioindicator organisms and human biological samples, as well as their health effects on humans, are also considered in this study.

Chromatographic analysis of dithiocarbamate residues and their metabolites in foods employed in dietary exposure studies-a review

Dithiocarbamates (DTCs) belong to a group of compounds used as fungicides in food production and can be divided into three major groups. Since DTCs easily oxidise and hydrolyse in alkaline and acidic medium respectively, precautions have to be implemented during preparation/homogenisation and extraction of samples. As such, test samples are commonly prepared individually by cutting into small pieces just before the digestion of DTCs with a hot acid to give carbon disulphide (CS₂) and the results are expressed as CS₂ without any differentiation of individual DTCs. However, individual DTCs have different toxicological potencies whilst their metabolites are more toxic than the parent compound. Apart from the hot digestion method, chromatographic separation of three major groups of DTCs has been developed by a number of different researchers. This review provides a comprehensive examination of sample preparation, extraction, clean-up and chromatographic methods for the determination of individual DTCs and their more toxic metabolites in foodstuffs. Moreover, this review also studies on how dietary exposure of DTCs can be efficiently and effectively estimated using different methods of analysis.

Contamination of breast milk with lead, mercury, arsenic, and cadmium in Iran: a systematic review and meta-analysis

Breast milk is a complete food for the development of the newborn, but it can also be an important route for environmental pollutants transmission to the infants. This study was aimed to evaluate the status of heavy metals including lead (Pb), mercury (Hg), cadmium (Cd) and arsenic (As) in the breast milk of Iranian mothers. The international databases including Scopus, PubMed, Web of Science and the Persian electronic databases including Scientific Information Database, IranMedex and Magiran were examined to find relevant articles published until July 2021. A total of 23 studies examined the levels of toxic metals in Iranian breast milk samples. According to the findings, the pooled average concentrations (µg/L) of Pb, Cd, Hg and As were 25.61, 2.40, 1.29 and 1.16, respectively. The concentration of Hg and Pb in colostrum milk was more than twice of mature milk. The Hg mean concentration in the breast milk of mothers with at least one amalgam-filled tooth was approximately three times that of mothers without amalgam-filled teeth. Risk assessment analysis indicated that the intake of Pb and Hg by infants through breastfeeding can be considered a health concern in Iran. It seems necessary to reduce the Pb exposure of pregnant and lactating women in Iran. However, more extensive studies are needed to clarify the toxic metals' exposure status of infants through breast milk in other parts of the country.