An open dataset of anticoagulant rodenticides in liver samples from California kingsnakes and raptors in Gran Canaria (Canary Islands, Spain).

It is well known that rodenticides are widely used, and there are multiple routes by which they can reach non-target wildlife species. Specifically, in the Canary Islands, a high and concerning incidence of these compounds has been reported. However, in this scenario, reptiles remain one of the least studied taxa, despite their potential suitability as indicators of the food chain and environmental pollution has been noted on several occasions. In this context, the California Kingsnake (Lampropeltis Californiae), widely distributed on the island of Gran Canaria, occupies a medium trophic level and exhibits feeding habits that expose it to these pollutants, could be studied as a potential sentinel of exposure to these compounds. For this reason, 360 snake livers were analyzed by LC-MS/MS. Similarly, 110 livers of birds of prey were sampled. Thus, we present the analysis of 10 anticoagulant rodenticides (warfarin, diphacinone, chlorophacinone, coumachlor, coumatetralyl, brodifacoum, bromadiolone, difethialone, difenacoum and flocoumafen) in both data series; snakes, and raptors. Furthermore, this dataset includes biological data (weight, length, sex, colour, and design pattern), geographic data (distribution area and municipalities) and necropsy findings that could be of interest for a better understanding of this snake species and for future studies.

Validation of a Method Scope Extension for Simple Biomonitoring of 353 Pollutants in Serum Samples.

Animals and humans are exposed to various residues that can have a detrimental impact on health, including carcinogenic potential, endocrine disruption, or fatal toxicity. The toxic burden can be evaluated in several biological samples, with serum being one of the preferred and most convenient options. In this study, we have applied and validated a method for detecting several hundred toxins in serum samples. This technique involved a single-step QuEChERS (quick, easy, cheap, effective, rugged, and safe) extraction followed by analysis using gas and liquid chromatography coupled with mass spectrometry. With this methodology, we could detect and quantify up to 353 compounds, including persistent organic pollutants (POPs), pesticides, pharmaceuticals, and rodenticides, using just 250 µL of serum. Among them, 92% could be measured at concentrations below 1.25 ng/mL, making it ideal for biomonitoring. We applied this method to samples collected from camels (n = 40) and humans (n = 25). We detected naproxen, ketoprofen, paracetamol, levamisole, and some POPs in these samples. This study validated the ability to simultaneously detect a broad range of compounds in small volumes of serum.

Human biomonitoring of persistent and non-persistent pollutants in a representative sample of the general population from Cape Verde: Results from the PERVEMAC-II study.

International Public Health authorities recommend biomonitoring studies to assess the exposure to chemicals in the general population. The aim of the present study was to analyze the blood concentrations of a total 360 pollutants, including 230 pesticides in current or recent use, 59 persistent organochlorine pollutants (POPs), 11 anticoagulant rodenticides and 60 pharmaceutical active compounds (PhACs), in a cohort of 403 subjects from Cape Verde. The study was performed in the frame of the Pesticide Residues in Vegetables of the Macaronesia project (PERVEMAC-II). A total of 60 out of 360 toxic compounds (16.7%) were detected, at least, in one participant. The three most frequently detected substances were p,p'-DDE (100%), phenanthrene (94.0%) and hexachlobenzene (35.9%). 2-Phenylphenol and imidacloprid were detected in 29.0 and 14.4% of the population. The three substances with the highest serum concentrations were PhACs: naproxen (249.1 ng/mL), metronidazole (115.6 ng/mL) and acetaminophen (25.2 ng/mL). Median blood concentration of p,p'-DDE, HCB and phenanthrene were 1.87, 0.08 and 0.36 ng/mL. Blood concentrations of POPs were influenced by age, although both gender and body mass index may exert an influence in the presence of these substances. Lifestyle has an effect on the concentration of these substances, especially in terms of dietary habits. Both the frequency of detection and the concentration of the studied substances are similar to those of other biomonitored populations. This is the first biomonitoring study carried out in Cape Verde. Our results may be useful for the implementation of public health measures by the competent authorities.

Comparative study of organic contaminants in agricultural soils at the archipelagos of the Macaronesia.

The occurrence of organic pollutants in soil is a major environmental concern. These compounds can reach the soil in different ways. Point sources, related to pesticides that are used intentionally, can be applied directly to the soil, or reach the soil indirectly due to application to the aerial parts of crops. On the other hand, non-point sources, which reach soils collaterally during irrigation and/or fertilization, or due to the proximity of plots to industrialized urban centers. Long-range transport of global organic pollutants must also be taken into account. In this study, 218 pesticides, 49 persistent organic pollutants, 37 pharmaceutical active compounds and 6 anticoagulant rodenticides were analyzed in 139 agricultural soil samples collected between 2018 and 2020 in the Macaronesia. This region comprised four inhabited archipelagos (Azores, Canary Islands, Cape Verde, and Madeira) for which agriculture is an important and traditional economic activity. To our knowledge, this is the first study on the levels of organic compound contamination of agricultural soils of the Macaronesia. As expected, the most frequently detected compounds were pesticides, mainly fungicides and insecticides. The Canary Islands presented the highest number of residues, with particularly high concentrations of DDT metabolites (p,p' DDE: 149.5 ± 473.4 ng g-1; p,p' DDD: 16.6 ± 35.6 ng g-1) and of the recently used pesticide fenbutatin oxide (302.1 ± 589.7 ng g-1). Cape Verde was the archipelago with the least contaminated soils. Very few pharmaceutical active compounds have been detected in all archipelagos (eprinomectin, fenbendazole, oxfendazole and sulfadiazine). These results highlight the need to promote soil monitoring programs and to establish maximum residue limits in soils, which currently do not exist at either continental or local level.

Impact of chemical elements released by the volcanic eruption of La Palma (Canary Islands, Spain) on banana agriculture and European consumers.

The recent volcanic eruption on the island of La Palma has aroused the concern of banana producers and consumers, given that in its area of influence there are thousands of hectares of banana plantations with an annual production of about 100 million kilos for export. Since volcanoes are one of the main natural sources of heavy metal contamination, we sampled bananas from the affected area and determined the concentrations of 50 elements (Ag, Al, As, Au, Ba, Be, Bi, Cd, Ce, Co, Cr, Cu, Cu, Dy, Er, Eu, Fe, Ga, Gd, Hg, Ho, In, La, Lu, Mn, Mo, Nb, Nd, Ni, Os, Pb, Pd, Pm, Pr, Pt, Sb, Sc, Se, Sm, Sn, Sr, Ta, Tb, Th, Ti, Tl, Tm, U, Y, Yb and Zn). The levels of 36 elements were elevated but the washing implemented after the eruption can remove a good part. After the washout, bananas have elevated levels of Fe, Al, Ti, V, Ba, Pb, most of the rare earth elements, Mo, and Co. In all cases, except Mo, the elevation is much higher in the peel than in the flesh. In the case of Mo, the elevation in banana flesh would translate into a higher nutritional intake of this trace element, which could represent up to 35% of the daily nutritional requirements. Exposure to toxic or potentially toxic elements, does not represent a health risk, since would not exceed 5% of the tolerable daily intake, even in the worst-case scenario.

A Method Scope Extension for the Simultaneous Analysis of POPs, Current-Use and Banned Pesticides, Rodenticides, and Pharmaceuticals in Liver. Application to Food Safety and Biomonitoring.

The screening of hundreds of substances belonging to multiple chemical classes in liver is required in areas such as food safety or biomonitoring. We adapted a previous QuEChERS-based method in blood to the liver matrix and applied to these fields of study. The validation of the method allowed the inclusion of 351 contaminants, 80% with a LOQ < 2 ng/g. In the analysis of 42 consumer liver samples, we detected trace levels of 29 different contaminants. The most frequent and concentrated was 4,4'-DDE. POPs accounted for 66% of the compounds detected. In no case was the MRL reached for any of the contaminants detected. We also applied the method to 151 livers of wild birds to perform a biomonitoring pilot study in the Canary Islands. We detected 52 contaminants in 15 bird species. These were also mostly POPs, although high frequencies and concentrations of anticoagulant rodenticides (AR) and some other agricultural pesticides also stand out. POPs and AR contamination levels were significantly higher in terrestrial birds, raptors and particularly in nocturnal birds. Pesticide contamination levels were also higher in terrestrial birds, as well as in non-raptors and diurnal birds. The validated method is simple, robust, and sensitive and performs well in a variety of practical scenarios, where it can be carried out relatively quickly and inexpensively.

Epidemiology of Animal Poisonings in the Canary Islands (Spain) during the Period 2014-2021.

Animal poisoning is one of the greatest conservation threats facing wildlife. In a preliminary study in the oceanic archipelago of the Canary Islands, we showed that the degree of threat from this circumstance was very high-even higher than that reported in other regions of continental Europe. Consequently, a legal framework for the effective prosecution of the crime of wildlife poisoning came into force in 2014 in this region. We present the results of the investigation of 961 animals and 84 baits sent to our laboratory for the diagnosis of animal poisonings during the period 2014-2021. We were able to identify poison as the cause of death in 251 animals and 61 baits. Carbofuran stands out as the main agent used in this archipelago. We have also detected an increasing tendency to use mixtures of several pesticides in the preparation of baits. The entry into operation of two canine patrols has led to the detection of more dead animals in the wild and a greater number of poisoned animals. The percentage of poison positives is significantly higher in areas with lower population density, corresponding to rural environments, as well as in areas with greater agricultural and livestock activity.

Extension of an extraction method for the determination of 305 organic compounds in clay-loam soil to soils of different characteristics.

Soil is one of the environmental compartments most affected by pollution. From this medium, the organic compounds can be emitted to the groundwater, the atmosphere, or the biota. Thus, having adequate methods of analysis of organic pollutants in this matrix is essential. However, the soil is a very complex matrix whose organic and inorganic components can determine the degree to which they are retained. Therefore, the methods must account for the various soil characteristics. In this study, the performance of an extraction method that had been already validated in clay loam soils for more than 300 organic compounds of very different nature including pesticides, PhACs, ARs, and POPs has been evaluated in four additional representative soil types of the agricultural land of the Canary archipelago: sandy loam, sandy clay, clay and loamy sand. For this purpose, recovery experiments have been performed at a single concentration (50 ng g-1) in each soil type. When there is a significant difference according to the criteria applied for a given compound, a factor has been calculated to correct the difference in performance in each soil type.•These results allowed to broaden the range of soils that can be analyzed with the proposed methodology.•In the worst case, which is the loamy sand soil, the original methodology allows the analysis of 180 organic contaminants with adequate recoveries. For analytes outside the acceptable range in this soil and the other soil type analyzed, correction factors are proposed.

Nutritional Evaluation and Risk Assessment of the Exposure to Essential and Toxic Elements in Dogs and Cats through the Consumption of Pelleted Dry Food: How Important Is the Quality of the Feed?

Dry feed for pets lacks specific legislation regarding maximum residue limits for inorganic elements. The aim of the present study was to determine the content of 43 inorganic elements in dog and cat feed, studying whether there were differences according to the supposed quality of the food and performing the risk assessment for health. Thirty-one and thirty packages of pelleted dry food for cats and dogs, respectively, were analyzed. After acidic microwave-assisted digestion, elements were detected and quantified by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). In general, we did not observe important differences in the content of elements according to the supposed quality of the brand. Among trace elements, selenium and manganese are above the dietary reference value. Arsenic and mercury showed the highest acute hazard indexes, which make them risk factors for the health of dogs and cats. Aluminum, uranium, antimony and vanadium contents were above the toxic reference value and showed the highest acute hazard indexes. It is necessary to improve the legislation regarding the food safety of pets, for their health and to protect the rights of consumers.

Validation of a Method Scope Extension for the Analysis of POPs in Soil and Verification in Organic and Conventional Farms of the Canary Islands.

Persistent organic pollutants (POPs) are among the most relevant and dangerous contaminants in soil, from where they can be transferred to crops. Additionally, livestock animals may inadvertently consume relatively high amounts of soil attached to the roots of the vegetables while grazing, leading to indirect exposure to humans. Therefore, periodic monitoring of soils is crucial; thus, simple, robust, and powerful methods are needed. In this study, we have tested and validated an easy QuEChERS-based method for the extraction of 49 POPs (8 PBDEs, 12 OCPs, 11 PAHs, and 18 PCBs) in soils and their analysis by GC-MS/MS. The method was validated in terms of linearity, precision, and accuracy, and a matrix effect study was performed. The limits of detection (LOD) were established between 0.048 and 3.125 ng g-1 and the limits of quantification (LOQ) were between 0.5 and 20 ng g-1, except for naphthalene (50 ng g-1). Then, to verify the applicability of the validated method, we applied it to a series of 81 soil samples from farms dedicated to mixed vegetable cultivation and vineyards in the Canary Islands, both from two modes of production (organic vs. conventional) where residues of OCPs, PCBs, and PAHs were found.

Postmortem investigations on leatherback sea turtles (Dermochelys coriacea) stranded in the Canary Islands (Spain) (1998-2017): Evidence of anthropogenic impacts.

Opportunities for postmortem studies on leatherback sea turtles (Dermochelys coriacea) are infrequent due to their predominantly pelagic life history. In this study, the pathological findings and causes of mortality of 13 leatherback turtles stranded in the Canary Islands, Spain, from 1998 to 2017, are described. In addition, concentrations of Se, As, Cd, Pb, Hg, 15 rare earth elements (REE) and other 4 minor elements (ME), 41 persistent organic pollutants, and 16 polycyclic aromatic hydrocarbons in hepatic samples from 5 leatherbacks were determined. 84.62% of the turtles died possibly due to anthropogenic causes (entanglement/fishing interaction - 46.15%; boat strike - 23.07%; plastic ingestion - 15.38%). Although Se, As, and Cd were found at higher hepatic concentrations than those reported for leatherbacks from other locations, no acute lesions were detected. This is the first report of exposure to REE-ME in sea turtles. Organic contaminant hepatic concentrations were generally low or undetectable.

An Easy Procedure to Quantify Anticoagulant Rodenticides and Pharmaceutical Active Compounds in Soils.

A modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) extraction was validated for the extraction of seven coumarin anticoagulant rodenticides (ARs) and 36 pharmaceutical active compounds (PhACs) residues in soil samples using liquid chromatography tandem mass spectrometry (LC-MS/MS). The aim of this work was to develop a method for the monitoring of these compounds in agricultural lands as well as in forensic applications for the determination of ARs poisoning. As far as is known, this is the first time that a QuEChERS-based method is used for the extraction of ARs in soil, as well as on such a quantity of PhACs. A matrix effect study was carried out on samples of soil devoted to agriculture in the midland area of the Canary Islands (clay loam type). It was in house validated (accuracy, precision, and linearity) at seven spiked levels between 0.5 and 50 ng g-1. The limits of quantification (LOQ) ranged between 0.5 and 50.0 ng g-1 and the limits of detection (LOD) ranged from 0.024 to 6.25 ng g-1. The method was then successfully used for both the determination of the target analytes in the soils from the agricultural plots that had been irrigated with regenerated water, and in the soil collected from underneath wild bird carcasses (which had been the subject of forensic investigation).

Dataset on the concentrations of anticoagulant rodenticides in raptors from the Canary Islands with geographic information.

The dataset presented in this article supports "Intensive livestock farming as a major determinant of the exposure to anticoagulant rodenticides in raptors of the Canary Islands (Spain)" (Rial-Berriel et al., 2020). A Geographic Information System (GIS) analysis on the influence of the influence of livestock activity on exposure to anticoagulant rodenticides in raptors in the Canary Islands was performed. This dataset provides geographic information on the localization of each raptor (either positive or negative for anticoagulant rodenticides, n = 308), as well as the concentrations of each compound found in their livers. In addition, we present complementary analyses to those included in the main article, such as the detailed analysis of the farming activity influence on anticoagulant rodenticide exposure of raptors, by island and by raptor species.

Intensive livestock farming as a major determinant of the exposure to anticoagulant rodenticides in raptors of the Canary Islands (Spain).

The Canary Islands (Spain) is a biodiversity hotspot, with more than 4500 registered endemic species. However, it is subject to high anthropogenic pressure that threatens its wildlife in various ways. In the context of forensic toxicological surveys, the presence of anticoagulant rodenticides (AR) has been investigated in the liver of 831 animal carcasses with georeferenced data from 2011 to May 2020. The high concentrations of toxic pesticides in carcasses and in baits found close to the corpses indicated that all the reptiles and most of the mammals tested positive for AR were intentionally poisoned, although mainly by other substances. The frequency of detection of AR in non-raptor birds (n = 343) was only 4.1%, being the Canary raven the most frequently affected species (7/97, 7.2%). On the contrary, in raptors (n = 308) the detection frequency was almost 60%, with an average of more than 2 ARs per animal. The highest concentrations were found in the common kestrel. We present for the first-time results of AR contamination in two species of raptors that are very rare in Europe, Eleonora's falcon (n = 4) and Barbary falcon (n = 13). The temporal trend of positive cases remains stable, but since the entry into force of the restriction to the concentration of the active ingredient in baits (<30 ppm), a decrease in the concentrations of these compounds in the raptors' liver has been detected. Conversely, we registered an increase in the number of ARs per animal. From the study of the geographic information system (GIS) it can be deduced that intensive livestock farms are an important determinant in the exposure of raptors to ARs. Those birds that have their territory near intensive production farms have higher levels of exposure than those of birds that live far from such facilities.

Optimization and validation of a QuEChERS-based method for the simultaneous environmental monitoring of 218 pesticide residues in clay loam soil.

A modified QuEChERS method was optimized, validated and verified for the extraction of 218 pesticide residues in agricultural soil samples. The 218 analytes are extracted using a single step, without clean-up, with matrix-matched calibration, and two complementary techniques: liquid and gas chromatography tandem triple quad mass spectrometry (LC-MS/MS and GC-MS/MS). Some of the parameters such as salts, acidity of the extraction solvent, sample moisture and some mechanical changes in the procedure were optimized to improve the overall performance for the target compounds and the soil matrix. The method was fully validated on a representative agricultural soil sample of the Canary Islands (clay loam soil) in terms of linearity, accuracy and precision. To avoid matrix effects, matrix-matched calibration curves (R2 ≥ 0.99) were used for all target analytes. 100% of the compounds can be quantified with limits of quantification (LOQ) lower than the limit typically used in soils (50 ng g-1), with 92% of compounds presenting a LOQ that is at least 10 times lower than that normally required. The limits of detection (LOD) ranged between 0.024 and 6.25 ng g-1. The validated method was applied to a series of actual samples of agricultural soil (n = 18). In addition, as a further verification of its potential, the results of the application of the method in the investigation of clay loam soil samples that were obtained from underneath wildlife carcasses in the context of an environmental forensic investigation are also presented.

Supporting dataset on the optimization and validation of a QuEChERS-based method for the determination of 218 pesticide residues in clay loam soil.

The dataset presented in this article supports "Optimization and validation of a method for the simultaneous environmental monitoring of 218 pesticide residues in clay loam soil" [1]. A method based on QuEChERS (Quick, Easy, Cheap, Effective, Rugged & Safe) for the extraction of pesticide and some metabolites residues was developed. The quantification of the chemicals was performed by a combination of two complementary LC-MS/MS and GC-MS/MS analyses. Detailed optimization data of the QuEChERS extraction method is provided, including (1) salt combination, (2) acidification of the solvent (3) the amount of the selected acid (Formic Acid, FA) and (4) moisturization of the soil samples prior to extraction. In addition, all the validation data are presented, including the matrix effect, which was evaluated for each analyte using the recommended procedure.

Supporting dataset on the validation and verification of the analytical method for the biomonitoring of 360 toxicologically relevant pollutants in whole blood.

The dataset presented in this article supports "Micro QuEChERS-based method for the simultaneous biomonitoring in whole blood of 360 toxicologically relevant pollutants for wildlife" (Rial-Berriel et al., 2020). The supplementary data are: (1) Detailed validation data of the LC-MS/MS and GC-MS/MS methods for the quantification of 360 chemicals covering bias and precision (intra- and inter-day variability) for retention times, linearity, and limits of quantification. (2) Graphical data of the matrix effects on the quantification of all of the analytes. (3) Individual data of the 51 chemicals detected in real whole blood samples from two raptor species: 36 barn owls (Tyto alba) and 112 common kestrels (Falco tinnunculus).

Micro QuEChERS-based method for the simultaneous biomonitoring in whole blood of 360 toxicologically relevant pollutants for wildlife.

This work presents the optimization, validation, and verification of a miniaturized method for the determination of 360 environmental pollutants that are of toxicological concern for wildlife. The method implies a one-step QuEChERS-based extraction of 250 µl whole blood using acidified acetonitrile, followed by two complementary analyses by LC-MS/MS and GC-MS/MS. The optimized conditions allow the simultaneous determination of the major persistent organic pollutants, a wide range of plant protection products, rodenticides, pharmaceuticals, and a suite of metabolites that can be used as biomarkers of exposure. The method is very sensitive, and 95% of the pollutants can be detected at concentrations below 1.5 ng/ml. The method was applied to a series of 148 samples of nocturnal and diurnal wild raptors collected during field ecological studies in 2018 and 2019. Fifty-one different contaminants were found in these samples, with a median value of 7 contaminants per sample. As expected, five of the six contaminants that were detected in >50% of the samples were persistent or semi-persistent organic pollutants. However, it is striking the high frequency of detection of some non-persistent pollutants, such as 2-phenylphenol, benalaxyl, metaflumizone, diphenylamine, brodifacoum or levamisole, indicating the penetration of these chemicals into the food chains. The toxicological significance of all these findings should be studied in depth in future research. However, the results clearly demonstrated that the approach developed provides reliable, simple, and rapid determination of a wide range of pollutants in wildlife and makes it very useful to obtain valuable data in biomonitoring studies with only small amounts of sample.

Risk assessment of the exposure to mycotoxins in dogs and cats through the consumption of commercial dry food.

Dry feed for dogs and cats sold in Europe are mostly formulated with cereals and cereal by-products, so the contamination of this food with mycotoxins represents a potential risk for these pets. We analyzed a representation of the best-selling feed brands in Spain. The presence of Aflatoxins (B1, B2, G1, and G2), Ochratoxin A, T-2 and HT-2 toxins, Deoxynivalenol, Zearalenone, and Fumonisins (B1 and B2) was quantified, using immunoaffinity columns and LC-MS/MS. In general, mycotoxins were frequently and simultaneously (6-11) detected, with AFB1, FB1, FB2, Deoxynivalenol, and HT-2 detected in 100% of the samples. However, the concentrations of most of them are among the lowest reported so far. Fumonisins were the exception since we report the highest concentrations to date, particularly in cat feed. We practically found no significant differences in the level of mycotoxin contamination in relation to the presumed quality of the feed. We also calculated the daily exposure, and evaluated the acute and chronic health risk posed by these feeds. None of the brands analyzed presented acute risk for any of the mycotoxins. However, the high levels of fumonisins found in some samples could become problematic, if there are hidden forms of them. This is also evident in relation to long-term risk, since in the case of fumonisins the level of exposure exceeds the tolerable daily intake level in 3.5 and 12 times, for dogs and cats respectively. The exposure levels to zearalenone and deoxynivalenol could also be of long-term concern, especially considering the possibility that the continuous exposure to several mycotoxins simultaneously might produce potentiated toxic effects as a result of their synergistic action. Further research on the potential adverse health effects deriving from chronic exposure to low doses of multi-mycotoxin mixtures in pets is needed.

Association between prenatal exposure to multiple persistent organic pollutants (POPs) and growth indicators in newborns.

Despite the fact that many of persistent organic pollutants (POPs) have been banned for decades, they still constitute a group of harmful substances to human health. Prenatal exposure can have adverse effects on one's health as well as on their newborns. The present cross-sectional study, which includes 87% of the births registered in La Palma Island (Canary Islands, Spain) during 2016 (n = 447), aims to evaluate the potential adverse health effects exerted by a wide range of POPs on newborns. We quantified blood cord levels of twenty organochlorine pesticides, eighteen polychlorinated biphenyls (PCBs), eight bromodiphenyl ethers (BDEs), and sixteen polycyclic aromatic hydrocarbons (PAHs) using the method of gas chromatography-mass spectrometry. By groups, p,p'-DDE, PCB-28, BDE-47, and phenanthrene were the most frequently detected compounds (median values = 0.148, 0.107, 0.065, and 0.380 ng/mL, respectively). p,p'-DDE was found to be significantly associated with an increase in neonatal birth weight, with a special emphasis on girls. An inverse association between PCB-28 and PCB-52 with birth weight was observed, and these associations were determined by the gender. A similar trend was obtained for BDE-47 but not for any of the PAHs. When assessing the effect of mixtures, boys exhibiting ≥ 3 OCPs were at lower risk of having higher birth weight (OR = 0.25; 95% CI = 0.07 - 0.89; P = 0.032). The effect of these pollutants on birth weight does not go in the same direction, a fact that is conditioned by several factors, including the chemical nature of the substance or the gender of the newborn. Additional research is needed to understand the role of POPs on fetal development.