Influence of chlorocholinechloride-treated wheat on selected in vitro fertility parameters in male mice

The disrupting effect of chlormequat chloride on growth hormone is associated with pregnancy

Since chlormequat chloride is widely applied as a plant growth regulator in agriculture and horticulture, its exposure through food consumption is common. We demonstrated previously that chlormequat chloride exposure during pregnancy led to embryos with bigger sizes associated with higher levels of growth hormone (GH) on gestation day 11 (GD11). However, the dose-effect relationship of chlormequat chloride at a lower dose range was not established, and the underlying mechanisms of its promoting effects on embryonic growth and development were not fully elucidated. To address these, pregnant rats were orally exposed to chlormequat chloride at 0, 0.05, 0.5 and 5 mg/kg.bw from GD0 to 11 and the embryonic growth and growth related hormones were evaluated on GD11. We found that the growth and development of the embryos was significantly promoted in a dose dependent manner by chlormequat chloride. Chlormequat chloride also increased embryonic GH, GH releasing hormone (GHRH), and somatostatin (SRIF), and inhibited the embryonic cAMP dependent protein kinase A (PKA) signaling pathway. Chlormequat chloride increased GH synthesis modulated by GHRH/SRIF-PKA-Pituitary specific transcription factor 1 (Pit-1) in the maternal rats. Intriguingly, chlormequat chloride did not show any effects on GH and PKA signaling pathways in the non-pregnant female rats. These findings together suggest that the disrupting effect of chlormequat chloride on GH is associated with pregnancy.

A pilot study of chlormequat in food and urine from adults in the United States from 2017 to 2023

Chlormequat chloride is a plant growth regulator whose use on grain crops is on the rise in North America. Toxicological studies suggest that exposure to chlormequat can reduce fertility and harm the developing fetus at doses lower than those used by regulatory agencies to set allowable daily intake levels. Here we report, the presence of chlormequat in urine samples collected from people in the U.S., with detection frequencies of 69%, 74%, and 90% for samples collected in 2017, 2018-2022, and 2023, respectively. Chlormequat was detected at low concentrations in samples from 2017 through 2022, with a significant increase in concentrations for samples from 2023. We also observed high detection frequencies of chlormequat in oat-based foods. These findings and chlormequat toxicity data raise concerns about current exposure levels, and warrant more expansive toxicity testing, food monitoring, and epidemiological studies to assess health effects of chlormequat exposures in humans. IMPACT: This study reports the detection of chlormequat, an agricultural chemical with developmental and reproductive toxicity, in the U.S. population and U.S. food supplies for the first time. While similar levels of the chemical were found in urine sampled from 2017 to 2022, markedly increased levels were found in samples from 2023. This work highlights the need for more expansive monitoring of chlormequat in U.S. foods and in human specimens, as well as toxicological and epidemiological study on chlormequat, as this chemical is an emerging contaminant with documented evidence of low-dose adverse health effects in animal studies.

Reproductive and developmental toxicity of plant growth regulators in humans and animals

Plant growth regulators (PGRs) are currently one of the widely used pesticides, as being considered to have relatively low toxicity compared with other pesticides. However, widespread use may lead to overexposure from multiple sources. Exposure to PGRs is associated with different toxicity that affects many organs in our body, such as the toxicity to testis, ovaries, liver, kidneys and brain. In addition, some PGRs are considered potential endocrine disrupting chemicals. Evidence exists for development and reproductive toxicity associated with prenatal and postnatal exposure in both animals and humans. PGRs can affect the synthesis and secretion of sex hormones, destroy the structure and function of the reproductive system, and harm the growth and development of offspring, which may be related to germ cell cycle disorders, apoptosis and oxidative stress. This review summaries the reproductive and developmental toxicity data available about PGRs in mammals. In the future, conducting comprehensive epidemiological studies will be crucial for assessing the reproductive and developmental toxicity resulting from a mixture of various PGRs, with a particular emphasis on understanding the underlying molecular mechanisms.

Chlorocholine chloride induced testosterone secretion inhibition mediated by endoplasmic reticulum stress in primary rat Leydig cells

Chlorocholine chloride (CCC) is well acknowledged as a plant growth regulator and may be considered as a potential environmental endocrine disrupting chemical. In our previous studies, it was found that CCC exposure at a pubertal stage reduced the serum and testicular levels of testosterone, decreased the sperm motility and delayed the puberty onset. However, the molecular mechanisms of CCC-induced testosterone secretion disorders remain unclear. In this study, we found that CCC exposure above 20 μg/mL inhibited the secretion of testosterone in Sprague-Dawley rats Leydig cells. Proteomic and pathway enrichment analysis indicated that CCC might induce endoplasmic reticulum (ER) stress. Western blot detection showed CCC exposure at 100, 200 μg/mL increased the protein level of glucose-regulated protein 78 (GPR78), C/EBP-homologous protein (CHOP), the ubiquitin-conjugating enzyme E2 D1 (UBE2D1) and the ring finger protein (RNF185) in the Leydig cells. The Leydig cells treated with 4-phenyl butyric acid (4-PBA), an ER stress inhibitor, rescued the testosterone secretion disorders and alleviated CCC-induced increase in the ER stress related protein levels at 200 μg/mL CCC treatment. Overall, CCC in vitro exposure might disturb testosterone production of Leydig cells and endoplasmic reticulum stress was involved in it.

Effects of prenatal chlorocholine chloride exposure on pubertal development and reproduction of male offspring in rats

Chlorocholine chloride (CCC) promote plant growth as a regulator. Emerging evidence by our group showed that CCC might restrain the puberty onset and impair the reproductive functions in male rats through HPT axis. In this study, we further investigated the effects of prenatal CCC exposure on pubertal development, reproduction of male offspring in rats and explored the underlying mechanisms. The results showed that CCC of 137.5 and 200 mg/kg bw/day delayed the age of preputial separation (PPS), decreased the sperm motility of male offspring. PP1γ2 which is an essential protein in spermatogenesis reduced in 137.5 and 200 mg/kg bw/day groups. Crucial hormones involved in hypothalamic-puititary-testicular (HPT) axis decreased at postnatal day (PND) 30. It was indicated that CCC exposure in pregnancy might disturb the pubertal development, reproductive functions of male offspring through HPT axis and disturb the sperm motility through PP1γ2.

Chlormequat chloride promotes rat embryonic growth and GH-IGF-1 axis

Chlormequat chloride, a plant growth regulator, is widely applied in agriculture because it can promote sturdier growth of the crops. In this research, we found that rat embryo growth on GD11 was inhibited in vitro at 50 μg/ml but promoted in vivo at 75 mg/kg.bw by maternal oral exposure. Therefore, the concentrations of chlormequat chloride in the sera of the pregnant rats on gestation day (GD)11 were determined by a high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) test to be 1.94 ± 0.023 μg/ml, 3.84 ± 0.080 μg/ml, and 7.08 ± 0.11 μg/ml, respectively, when the pregnant rats were orally exposed to chlormequat chloride at 75, 137.5, and 200 mg/kg.bw. Hence, we performed WEC tests again and confirmed that the rat embryo growth in vitro was promoted by chlormequat chloride at 5 μg/mL. The embryonic growth hormone (GH) and insulin-like growth factor 1 (IGF-1) levels were increased by chlormequat chloride both in vitro and in vivo compared with the control ones. We concluded that chlormequat chloride could elevate GH and IGF-1 levels in embryos and promote embryonic growth both in vitro and in vivo.

Calibration of sperm concentration for in vitro fertilization in a mouse reprotoxicity model

Xenobiotics, such as chemicals and pesticides, may result in adverse effects on reproduction in human and animals. Using in-vitro embryo production as a testing system reveals details of fertilization (IVF) and early embryonic development (IVC). The aim of our study was to perform a systematical calibration of sperm concentration in an IVF/IVC system, using an outbred mouse strain, and further determine the sperm concentration that furnishes a sensitive assessment of sperm fertilizing capacity in relation to reprotoxic evaluations. By performing breakpoint analysis, the results revealed a maximum two-cell percentage (51%, 95% CI: 38 to 69%) at 3.6 × 10⁴ sperm/ml (95% CI: 2.1 × 10⁴ to 6.1 × 10⁴). For future application of the IVF/IVC system, a sperm concentration lower than this breakpoint concentration is required to be within the responsive range for determining sperm fertilizing capacity. We conclude that a relatively low sperm concentration (2.5 × 10⁴ sperm/ml) is a precondition in a mouse IVF/IVC system in order to detect potential reprotoxic effects on sperm fertilizing capacity. Our study illustrates that a systematic approach is necessary for validation and appropriate use of such in-vitro system used for reproductive toxicity testing.

Determination of chlormequat and mepiquat residues and their dissipation rates in tomato cultivation matrices by ultra-performance liquid chromatography-tandem mass spectrometry

This study described the development and validation of a simple, rapid, specific and sensitive method for detecting chlormequat chloride (CQ) and mepiquat chloride (MQ) residues in tomato cultivation matrices covering soil, water, seedling samples. The dissipation rates of CQ and MQ in tomato cultivation matrices were also determined in this study. A Hydrophilic Interaction Liquid Chromatography (HILIC) column was used for chromatographic separation. A triple quadrupole mass spectrometer equipped with an electrospray ionisation source in positive ion mode by multiple reaction monitoring was used for detection. Soil samples were extracted with accelerated solvent extraction (ASE) and cleaned up with WCX phase extraction column; water samples were extracted with WCX phase extraction column; seedling samples were extracted with methanol-ammonium acetate solution. LODs and LOQs of CQ and MQ were 0.02μg/kg and 0.1μg/kg in soil samples, 0.005ng/mL and 0.02ng/mL in water samples, and 0.05μg/kg and 1.0μg/kg in seedling samples, respectively. The mean recovery rate of CQ in soil, water and seedling samples ranged from 76.98% to 111.60%. While the mean recovery rate of MQ in soil, water and seedling samples ranged from 96.90% to 105.40%. The fastest to the slowest metabolising rates of CQ and MQ were as follows: soil samples>seedling samples>water samples. In conclusion, this study provided a new potential method for detecting CQ and MQ in tomato cultivation matrices using ultra-performance liquid chromatography-tandem mass spectrometry.

Ionic liquids based on 2-chloroethyltrimethylammonium chloride (CCC) as plant growth regulators

Plant growth regulator — 2-chloroethyltrimethylammonium chloride (CCC) was converted into ionic liquid in the metathesis reaction. New forms of CCC as ILs were stable in air as well in contact with water and organic solvents. The biological action of the cation (CCC) in ILs was preserved. Type of anion determined hydrophobicity and hydrophilicity of the whole molecule and it also influenced the biological activity of the plant growth regulator. All of the investigated salts retarded growth of winter wheat stems and most of them increased yield at the same time, when compared to control and standard 2-chloroethyltrimethylammonium chloride.

Rapid determination of chlormequat in meat by dispersive solid-phase extraction and hydrophilic interaction liquid chromatography (HILIC)-electrospray tandem mass spectrometry

A rapid method for analyzing trace levels of chlormequat (CQ) in meat samples by hydrophilic interaction liquid chromatography (HILIC)-electrospray tandem mass spectrometry was developed. The samples were extracted with acetonitrile, followed by a rapid cleanup through a dispersive solid-phase extraction (DSPE) technique with octadecyl (C18) DSPE sorbents. The chromatographic separation was achieved within 6 min using a HILIC column with 10 mM ammonium acetate and 0.1% (v/v) formic acid in water/acetonitrile (v/v, 40:60) as the mobile phase. Quantification was performed using a matrix-matched calibration curve, which was linear in the range of the 0.05-100 μg/L. The limit of detection (LOD) was estimated at 0.03 μg/kg for CQ on the basis of a peak to peak signal noise (S/N = 3). The limit of quantification (LOQ) was 0.1 μg/kg on the basis of the lowest spiked concentration with suitable precision and accuracy. The average recovery of CQ in spiked meat samples was 86.4-94.7% at 2, 20, and 200 μg/kg. Finally, this method was applied to determine CQ in the livestock and poultry meats purchased from markets in Beijing in 2011. CQ was detected in all 12 samples, and the concentration was 0.4-636.0 μg/kg. Concentrations in a chicken sample (636.0 μg/kg) and a goat meat sample (486.0 μg/kg) were found to be 15.9 and 2.43 times the corresponding Codex maximum residue limits, respectively.

Fate and transport of chlormequat in subsurface environments

BACKGROUND, AIM AND SCOPE

Chlormequat (Cq) is a plant growth regulator used throughout the world. Despite indications of possible effects of Cq on mammalian health and fertility, little is known about its fate and transport in subsurface environments. The aim of this study was to determine the fate of Cq in three Danish subsurface environments, in particular with respect to retardation of Cq in the A and B horizons and the risk of leaching to the aquatic environment. The study combines laboratory fate studies of Cq sorption and dissipation with field scale monitoring of the concentration of Cq in the subsurface environment, including artificial drains.

MATERIALS AND METHODS

For the laboratory studies, soil was sampled from the A and B horizons at three Danish field research stations-two clayey till sites and one coarse sandy site. Adsorption and desorption were described by means of the distribution coefficient (K (d)) and the Freundlich adsorption coefficient (K (F,ads)). The dissipation rate was estimated using soil sampled from the A horizon at the three sites. Half life (DT(50)) was calculated by approximation to first-order kinetics. A total of 282 water samples were collected at the sites under the field monitoring study- groundwater from shallow monitoring screens located 1.5-4.5 m b.g.s. at all three sites as well as drainage water from the two clayey sites and porewater from suction cups at the sandy site, in both cases from 1 m b.g.s. The samples were analysed using LC-MS/MS. The field monitoring study was supported by hydrological modelling, which provided an overall water balance and a description of soil water dynamics in the vadose zone.

RESULTS

The DT(50) of Cq from the A horizon ranged from 21 to 61 days. The Cq concentration-dependant distribution coefficient (K (d)) ranged from 2 to 566 cm(3)/g (median 18 cm(3)/g), and was lowest in the sandy soil (both the A and B horizons). The K (F,ads) ranged from 3 to 23 (microg(1 - 1/n ) (cm(3))(1/n) g(-1)) with the exponent (1/n) ranging from 0.44 to 0.87, and was lowest in the soil from the sandy site. Desorption of Cq was very low for the soil types investigated (<10%w). Cq in concentrations exceeding the detection limit (0.01 microg/L) was only found in two of the 282 water samples, the highest concentration being 0.017 microg/L.

DISCUSSION

That sorption was highest in the clayey till soils is attributable to the composition of the soil, the soil clay and iron content being the main determinant of Cq sorption in both the A and B horizons of the subsurface environment. Cq was not detected in concentrations exceeding the detection limit in either the groundwater or the porewater at the sandy site. The only two samples in which Cq was detected were drainage water samples from the two clayey till sites. The presence of Cq here was probably attributable to the hydrogeological setting as water flow at the two clayey till sites is dominated by macropore flow and less by the flow in the low permeability matrix. In contrast, water flow at the sandy site is dominated by matrix flow in the high permeability matrix, with negligible macropore flow. Given the characteristics of these field sites, Cq adsorption and desorption can be expected to be controlled by the clay composition and content and the iron content. Combining these observations with the findings of the sorption and dissipation studies indicates that the key determinant of Cq retardation and fate in the soil is sorption characteristics and bioavailability.

CONCLUSIONS

The leaching risk of Cq was negligible at the clayey till and sandy sites investigated. The adsorption and desorption experiments indicated that absorption of Cq was high at all three sites, in particular at the clayey till sites, and that desorption was generally very limited. The study indicates that leaching of Cq to the groundwater is hindered by sorption and dissipation. The detection of Cq in drainage water at the clayey till sites and the evidence for rapid transport through macropores indicate that heavy precipitation events may cause pulses of Cq.

RECOMMENDATIONS AND PERSPECTIVES

The present study is the first to indicate that the risk of Cq leaching to the groundwater and surface water is low. Prior to any generalisation of the present results, the fate of Cq needs to be studied in other soil types, application regimes and climatic conditions to determine the Cq retardation capacity of the soils. The study identifies bioavailability and heavy precipitation events as important factors when assessing the risk of Cq contamination of the aquatic environment. The possible effects of future climate change need to be considered when assessing whether or not Cq poses an environmental risk.

Determination of chlormequat in pig serum and sow milk by LC–MS/MS

Chlormequat is a plant growth regulator widely used on cereals, and there is general concern that it may impair human fertility. A LC-MS/MS method for the analysis of chlormequat in milk and serum was developed and validated in connection with an investigation on the effect of chlormequat on pig reproduction. Validation of the method was based on recovery tests at three spiking levels, determined as double determinations and repeated at least four times. Samples were extracted with methanol-water-acetic acid, centrifuged, filtrated and determined by LC-MS/MS. The mean recoveries were in the range 80-110%, and the LOD was 0.2 ng/g for serum and 0.3 ng/g for milk. The values for repeatability and reproducibility were within 2/3 of the limits given by the Horwitz equation. Samples of pig serum (59) and sow milk (27) were analyzed using the method. Chlormequat was determined in four milk samples in the range of 0.4 ng/g to 1.2 ng/g and in all serum samples in the range of 0.2 ng/g-4.0 ng/g.

Effects of the plant growth regulator, chlormequat, on mammalian fertility

This paper summarizes the consequences of exposure to chlormequat, a plant growth regulator, on reproduction in mammals. Plant growth regulators are chemicals used to manipulate plant growth, flowering and fruit yield. In grain crops, plant growth regulators are applied to promote sturdier growth and reduce the risk of lodging. Chlormequat is the most common plant growth regulator. Maximum residue limits of chlormequat in food products are 10 mg/kg in oat and pear, 3 mg/kg in wheat and rye, and 0.5 mg/kg in milk. In Denmark, results from experiments with pigs in the late 1980s showed sows that display impaired reproduction, mainly impaired oestrus, when fed grain from crop treated with chlormequat. Subsequently, the advisory body to the Danish pig industry recommended limiting the use of grain (maximum 30% of diet energy) from crop treated with chlormequat given to breeding stock due to the risk of reproduction problems. More recently, experiments have been conducted to evaluate the influence of chlormequat-treated wheat crop on reproductive function in male and female mice. These experiments showed that epididymal spermatozoa from mice on feed or water containing chlormequat had compromised fertilizing competence in vitro, while reproduction in female mice was not compromised. The estimated intake of chlormequat in the pig (0.0023 mg/kg bw/day) and the mouse (0.024 mg/kg bw/day) experiments was below the acceptable daily intake of 0.05 mg/kg bw/day. Reports from the industry do not show any effects at these low levels.

Rapid method for determination of chlormequat residues in tomato products by ion-exchange liquid chromatography/electrospray tandem mass spectrometry

A rapid method has been devised for the direct determination of chlormequat in tomato samples. No clean-up is required, and analysis uses ion-exchange liquid chromatography/tandem mass spectrometry interfaced with electrospray ionization (LC/ESI-MS/MS). A cation-exchange column was used with an aqueous ammonium acetate/acetonitrile mixture as the mobile phase under isocratic conditions. The method was validated in terms of detection limits (LOD), quantitation limits (LOQ), linearity, recovery, precision and accuracy. Good results in the low micro g kg(-1) level were obtained for the LOD and LOQ of chlormequat in tomato samples. Comparison of solvent and matrix-matched calibration curves demonstrated the absence of significant matrix effects and the feasibility of using external calibration. Linearity was established over two orders of magnitude by performing homoscedasticity and Mandel fitting statistical tests. The absence of both constant and proportional systematic errors was verified by evaluating the recovery function, demonstrating good method accuracy. Excellent precision in terms of intra-day repeatability was calculated (RSD% <3.4). Extraction recoveries from tomato products were calculated, by using a labelled internal standard (d(4)-chlormequat), to be in the 93 +/- 5-99 +/- 7% range. The applicability of the method to the determination of chlormequat residues in tomato products was demonstrated.