Temporal distribution and ecological risk assessment for pesticides in water from the north-central coastal zone of Sinaloa, Mexico.

Water contamination with pesticides is one of the major pollution problems in northwestern Mexico, and this is due to the extensive use of pesticides in agriculture. In this research, water samples of ten sampling sites (fishing grounds, beaches, and both) were analyzed in the search for 28 pesticides (organochlorines, organophosphates, pyrethroids, carbamates, among other chemical classes), supplemented with a calculation of the resulting potential environmental risk. Pesticides were separated from the matrix by liquid-liquid extraction and quantified by gas chromatography coupled to electron micro-capture (organohalogenated) and pulsed flame photometric detectors (organophosphates). In addition, the ecotoxicological risk of pesticides in algae, invertebrates, and fish was assessed, based on seawater pesticide concentrations using the Risk Quotient (RQ) and Toxic Units (TU) approach. The results showed 18 pesticides identified in the analyzed samples, where cypermethrin and chlorpyrifos were identified with the maximum concentrations of 1.223 and 0.994 µg L-1, respectively. In addition, these two pesticides have been associated with acute toxic effects on algae, invertebrates, and fish. It is important to pay particular attention to the search for long-term alternatives to the use of chlorpyrifos and cypermethrin due to their high detection rates and the risks associated with their toxic properties. However, the adoption of alternative measures to synthetic pesticide control should be a priority, moving towards sustainable practices such as the use of biopesticides, crop rotation and polycultures.

Pesticide levels in shrimp on Mexican coasts.

The present review aimed to evaluate the current situation of pesticide residues detected in shrimp (commercial species) on the Mexican coasts. The organochlorine pesticides (OC), α-endosulfan (210.01 ng g-1), endosulfan sulfate (127.5 ng g-1), heptachlor (126.04 ng g-1 and γ-HCH (121.04 ng g-1) are identified as the most common pesticides in shrimp tissues, with the Northwest area reporting the highest concentrations of these OC. Given that there is an under-evaluation of pesticide residue levels, there was a greater contribution of studies directed at the Northwest of the country considering that there are states that are among the main shrimp-producing and consumers entities. The concentrations and types of pesticides banned nationally and globally, due to their toxic effects on the population, were reported. Therefore, since the most current information is 19 years out of date, it is necessary to perform recent evaluations with sensible and precise methods.

Prebiotics in Global and Mexican Fish Aquaculture: A Review.

Continued human population growth has resulted in increased demand for products, including those derived from aquaculture. The main challenge in aquaculture is producing more every year. In recent years, environmentally friendly supplements that provide the necessary pathways for optimal production have been emphasized. One of them is prebiotics, selectively utilized substrates by host microorganisms conferring a health benefit. Interest in applying prebiotics in global fish farming has increased in recent years as it has been shown to improve growth, boost the immune system, resist stress conditions, and cause the modulation of digestive enzymes. These effects reflect reduced production and disease costs. However, in Latin American countries such as Mexico, large-scale use of these food supplements is needed as a sustainable alternative to improve fish production. This paper gives a review of the current advances obtained with the application of prebiotics in commercially farmed fish worldwide, mentions the prebiotics to use in the aquaculture industry, and updates the status of studies about the used prebiotics in global commercial fish cultivated in Mexico, as well as freshwater and marine endemic fish in this country. Also, the limitations of prebiotics application in terms of their use and legislation are analyzed.

Pesticides in water and sediments of Chacahua-Pastoria Lagoon System, Oaxaca, Mexico.

This is the first report about the presence of pesticide residues in water and sediments from Chacahua-Pastoria Lagoon System in the Oaxaca Coast, Mexico. Organochlorine and organophosphate pesticides were analyzed in water and sediment samples collected during rainy and dry seasons in 2018. The pesticides extraction was carried out by 525.2 EPA and QuEChERS methods for water and sediments samples, respectively. The quantification was done by gas chromatography coupled to electron microcapture (µECD) and flame photometric (FPD) detectors. Univariate and multivariate analysis were carried out to evaluate the distribution patterns, comparing between lagoons, seasons and matrices. The spatial distribution of malathion and organochlorines in water showed the highest values near to adjacent land with some patterns differences. DDT was the most frequent in water and sediments samples, showed the highest concentrations in the Pastoria Lagoon. These results indicate the need to establish a permanent monitoring programs to implement mitigation measures.

Agricultural pesticide residues in water from a karstic aquifer in Yucatan, Mexico, pose a risk to children's health.

Yucatan is a region with a high impact of water contamination since it has a karst type soil favoring contaminants entry into the phreatic level, the only source of freshwater in the area. However, no studies report pesticides in water for human consumption or the risk it represents. The objective of this study was to detect and measure pesticide concentrations in domestic tap water to estimate the risk (carcinogenic and non-carcinogenic) to health. A non-probabilistic sampling was applied of 48 tap water sources, and then pesticide detection with solid-phase extraction gas chromatography coupled to the electron capture and flame photometric detectors allowed the estimation of risk through hazard ratios. The present results suggest that aldrin, heptachlor, and ß-BHC residues in domestic tap water from Ticul, Yucatan, pose a risk to children's health, particularly for potential carcinogenic risks.

A comparison of pesticide residues in soils from two highly technified agricultural valleys in northwestern Mexico.

A pesticide characterization is presented for two highly technified valleys in northwest Mexico: Culiacan Valley (CV) in Sinaloa and Yaqui Valley (YV) in Sonora. Approximately 250,000 kg of active ingredients are used every year, half of which are considered highly hazardous pesticides. Legacy pesticides are still present in the soils of these valleys. The aim of the present study was to identify and quantify a wide variety of pesticides in soils and correlate their concentrations with historical and current use. Agricultural soils from both valleys were sampled and analyzed using accelerated solvent extraction and subsequent quantification by gas chromatography with selective detectors. The most frequently detected pesticides (mean, µg g-1) in CV were organochlorines (0.1967), organophosphates (0.0928), synthetic pyrethroids (0.2565), organonitrogen (0.0552), and miscellaneous pesticides (0.1851). In YV, the most frequently detected pesticides were organochlorines (0.8607), organophosphates (0.0001), synthetic pyrethroids (0.0124), and miscellaneous pesticides (0.0009). The pesticides were more diverse in CV compared to those of YV, which was based on the types of crops produced. Both locations presented highly hazardous pesticides, including concentrations above the action levels established by the Canadian Soil Quality Guide. A follow-up risk assessment is recommended to assess potential effects.

Chlorpyrifos and Dimethoate in Water and Sediments of Agricultural Drainage Ditches in Northern Sinaloa, Mexico.

In northern Sinaloa state, Mexico, little is known on organophosphate pesticide transport and fate in agricultural drainage systems. Spatial and temporal variation of chlorpyrifos and dimethoate was assessed in two agricultural drainage ditches (Buenaventura and Burrión) and risk for aquatic life was estimated. Analysis was made by high performance liquid chromatography and risk estimates were determined following international reference frameworks. In water, the highest chlorpyrifos concentration in the Buenaventura ditch was 5.49 µg L-1, and 3.43 µg L-1 in the Burrión ditch. Dimethoate was quantified only once in both ditches (0.44 µg L-1 and 0.49 µg L-1). In sediment, chlorpyrifos was quantified only in the Burrión ditch (242 µg kg-1). Chlorpyrifos concentrations surpassed water and sediment quality criteria, representing a hazard for environmental and human health, as both ditches discharge into the Gulf of California and are used for capture of commercial species such as the grey mullet (Mugil cephalus) and cauque prawn (Macrobrachium americanum).

Hollow fiber liquid-phase microextraction combined with supercritical fluid chromatography coupled to mass spectrometry for multiclass emerging contaminant quantification in water samples.

The hollow fiber liquid-phase microextraction allows highly selective concentration of organic compounds that are at trace levels. The determination of those analytes through the supercritical fluid chromatography usage is associated with many analytical benefits, which are significantly increased when it is coupled to a mass spectrometry detector, thus providing an extremely sensitive analytical technique with minimal consumption of organic solvents. On account of this, a hollow fiber liquid-phase microextraction technique in two-phase mode combined with supercritical fluid chromatography coupled to mass spectrometry was developed for quantifying 19 multiclass emerging contaminants in water samples in a total chromatographic time of 5.5 min. The analytical method used 40 µL of 1-octanol placed in the porous-walled polypropylene fiber as the acceptor phase, and 1 L of water sample was the donor phase. After extraction and quantification techniques were optimized in detail, a good determination coefficient (r2 > 0.9905) in the range of 0.1 to 100 µg L-1, for most of the analytes, and an enrichment factor in the range of 7 to 28,985 were obtained. The recovery percentage (%R) and intraday precision (%RSD) were in the range of 80.80-123.40%, and from 0.48 to 16.89%, respectively. Limit of detection and quantification ranged from 1.90 to 35.66 ng L-1, and from 3.41 to 62.11 ng L-1, respectively. Finally, the developed method was successfully used for the determination of the 19 multiclass emerging contaminants in superficial and wastewater samples.