Investigating the Allometric Relationship for Total Mercury in Male and Female Signal Crayfish (Pacifastacus leniusculus) from Three Regions in the Columbia River Basin, USA.

The objective of this study was to evaluate the relationship between clawless body mass (CBM) and total mercury concentration (THg) in male and female crayfish captured from three different sites in the Columbia River Basin: the Spokane River, Boise River and Hangman Creek. It was found that the allometric relationships for THg in male and female crayfish did not differ from one another at any of the three locations (Spokane River: ANCOVA, F1,49 = 0.001, p = 0.63; Hangman Creek: ANCOVA, F1,73 = 0.007, p = 0.93; Boise River: ANCOVA, F1,38 = 0.02, p = 0.88. Furthermore, the slopes of the CBM and THg regression lines were not significantly different from one site to the next (ANCOVA, F2,166 = 1.5 p = 0.24), despite considerable differences in mean mass-adjusted THg across locations (Spokane River: 26.8 ± 2.6; Hangman Creek: 75.2 ± 2.1; Boise River: 99.0 ± 2.9). For signal crayfish (Pacifastacus leniusculus) from the Columbia River Basin, size and sex standardization can be accomplished with a single linear relationship.

Pesticide exposure affects DNA methylation patterns in natural populations of a mayfly.

Chemical pollutants derived from agricultural activities represent a major threat to freshwater biota. Despite growing evidence involving epigenetic processes, such as DNA methylation, in response to pesticide contamination in agroecosystems, research on wild populations of non-model species remains scarce, particularly for endemic freshwater arthropods. Using the MethylRAD method, this study investigates whether exposure to pesticide contamination in natural populations of the endemic mayfly A. torrens produces genome wide changes in levels of DNA methylation. From a total of 1,377,147 MethylRAD markers produced from 285 specimens collected at 30 different study sites along the Limarí watershed of north-central Chile, six showed significant differential methylation between populations exposed and unexposed to pesticides. In all cases the effect of pesticides was positive, independent and stronger than the effects detected for other spatial and environmental factors. Only one candidate marker appeared correlated significantly with additional variables, nitrate and calcium levels, which also reflects the impact of agrichemicals and could additionally suggest, to a lower extent, antagonistic effects of mineral salts concentration for this specific marker. These results suggest that the effect of pesticide exposure on methylation levels is apparent at these six MethylRAD markers in A. torrens populations. Such data is challenging to obtain in natural populations and is, for the most part, lacking in ecotoxicological studies. Our study shows that DNA methylation processes are involved in the response to pesticide contamination in populations of the mayfly A. torrens in their natural habitat, and provides new evidence regarding the impact of pesticide contamination and agricultural activities on the endemic fauna of lotic ecosystems.

Evaluating the impact of turbidity, precipitation, and land use on nutrient levels and atrazine concentrations in Illinois surface water as determined by citizen scientists.

The objective of this study was to evaluate the impact of turbidity, precipitation, land use, and five-week variation on nutrient levels and atrazine concentrations across Illinois state. To acquire the greatest number of samples in a cost and time-sensitive manner, data were collected by citizen scientists. Volunteers collected data regarding five water quality metrics: nitrites, nitrates, phosphates, atrazine, and turbidity once per week from April 19 until May 17, 2017. A subset (24 %) of volunteers also collected turbidity measurements. Data regarding precipitation was obtained from the Community Collaborative Rain, Hail and Snow Network (CoCoRaHS), a long-standing grassroots volunteer network of backyard weather observers. Three ordinal regression analyses were performed: one without a blocking effect, a second with week as a blocking effect, and a third with watershed as a blocking effect. In all cases, turbidity was significantly associated with elevated levels of nitrate (Pseudo R2-0.48 to 0.94) and phosphate (Pseudo R2-0.60 to 0.80), while precipitation was significantly associated with elevated levels of nitrate (Pseudo R2-0.25 to 0.35). While analyzing five-week variation, the nitrite and nitrate levels, but not phosphate or atrazine, tended to increase at each site. Further, nitrite and nitrate levels significantly varied between the four land uses - agricultural, urban, suburban, and park. When data were analyzed by the three most well-sampled watersheds, Kankakee, Des Plaines, and Chicago, it was identified that the nutrient levels in the Kankakee and Chicago watersheds were significantly elevated relative to the Des Plaines watershed. Finally, cluster analysis identified that clusters dominated by agricultural land, and to a lesser extent suburban land use, had the most elevated nutrient concentration and the greatest frequency of atrazine hits. Data collected by citizen scientists can provide insight into the geospatial variability of nutrients and agrichemicals and can do so across large geographies.

Analysis of the contribution of locally derived wastewater to the occurrence of Pharmaceuticals and Personal Care Products in Antarctic coastal waters.

Pharmaceuticals and Personal Care Products (PPCPs) are emerging pollutants detected in many locations of the world including Antarctica. The main objective of this review is to discuss the influence of the human population on the concentration, distribution and biological effects of PPCPs across the Antarctic coastal marine ecosystem. We carried out a review of the scientific articles published for PPCPs in Antarctic, supported by the information of the Antarctic stations reported by Council of Managers of National Antarctic Programs (CONMAP), Scientific Committee on Antarctic Research (SCAR) and Secretariat of the Antarctic Treaty (ATS). In addition, spatial data regarding the Antarctic continent was obtained from Quantarctica. Antarctic concentrations of PPCPs were more reflective of the treatment system used by research stations as opposed to the infrastructure built or the annual occupancy by station. The main problem is that most of the research stations lack tertiary treatment, resulting in elevated concentrations of PPCPs in effluents. Furthermore, the geographic distribution of Antarctic field stations in coastal areas allows for the release of PPCPs, directly into the sea, a practice that remains in compliance with the current Protocol. After their release, PPCPs can become incorporated into sea ice, which can then act as a chemical reservoir. In addition, there is no clarity on the effects on the local biota. Finally, we recommend regulating the entry and use of PPCPs in Antarctica given the difficulties of operating, and in some cases the complete absence of appropriate treatment systems. Further studies are needed on the fate, transport and biological effects of PPCPs on the Antarctic biota. It is recommended that research efforts be carried out in areas inhabited by humans to generate mitigation measures relative to potential adverse impacts. Tourism should be also considered in further studies due the temporal release of PPCPs.

Chemical Toxicants in Water: A GeoHealth Perspective in the Context of Climate Change.

The editorial focuses on four major themes contextualized in a virtual GeoHealth workshop that occurred from June 14 to 16, 2021. Topics in that workshop included drinking water and chronic chemical exposure, environmental injustice, public health and drinking water policy, and the fate, transport, and human impact of aqueous contaminants in the context of climate change. The intent of the workshop was to further define the field of GeoHealth. This workshop emphasized on chemical toxicants that drive human health. The major calls for action emerged from the workshop include enhancing community engagement, advocating for equity and justice, and training the next generation.

Investigation of Relationships Between the Geospatial Distribution of Cancer Incidence and Estimated Pesticide Use in the U.S. West.

The objective of the study was to evaluate the potential geospatial relationship between agricultural pesticide use and two cancer metrics (pediatric cancer incidence and total cancer incidence) across each of the 11 contiguous states in the Western United States at state and county resolution. The pesticide usage data were collected from the U.S. Geological Survey Pesticide National Synthesis Project database, while cancer data for each state were compiled from the National Cancer Institute State Cancer Profiles. At the state spatial scale, this study identified a significant positive association between the total mass of fumigants and pediatric cancer incidence, and also between the mass of one fumigant in particular, metam, and total cancer incidence (P-value < 0.05). At the county scale, the relationship of all cancer incidence to pesticide usage was evaluated using a multilevel model including pesticide mass and pesticide mass tertiles. Low pediatric cancer rates in many counties precluded this type of evaluation in association with pesticide usage. At the county scale, the multilevel model using fumigant mass, fumigant mass tertiles, county, and state predicted the total cancer incidence (R-squared = 0.95, NSE = 0.91, and Sum of square of residuals [SSR] = 8.22). Moreover, this study identified significant associations between total fumigant mass, high and medium tertiles of fumigant mass, total pesticide mass, and high tertiles of pesticide mass relative to total cancer incidence across counties. Fumigant application rate was shown to be important relative to the incidence of total cancer and pediatric cancer, at both state and county scales.

Geospatial Distribution of Age-Adjusted Incidence of the Three Major Types of Pediatric Cancers and Waterborne Agrichemicals in Nebraska.

This study was conducted to examine, at the county level, the relationship between pediatric cancer incidence rate and atrazine and nitrate mean concentrations in surface and groundwater. A negative binomial regression analysis was performed to investigate the association between central nervous system (CNS) tumors, leukemia, lymphoma, and atrazine and nitrate mean concentrations in groundwater. The age-adjusted brain and other CNS cancer incidence was higher than the national average in 63% of the Nebraska counties. After controlling for the counties socio-economic status and nitrate concentrations in groundwater, counties with groundwater atrazine concentrations above 0.0002 µg/L had a higher incidence rate for pediatric cancers (brain and other CNS, leukemia, and lymphoma) compared to counties with groundwater atrazine concentrations in the reference group (0.0000-0.0002 µg/L). Additionally, compared to counties with groundwater nitrate concentrations between 0 and 2 mg/L (reference group), counties with groundwater nitrate concentrations between 2.1 and 5 mg/L (group 2) had a higher incidence rate for pediatric brain and other CNS cancers (IRR = 8.39; 95% CI: 8.24-8.54), leukemia (IRR = 7.35; 95% CI: 7.22-7.48), and lymphoma (IRR = 5.59; CI: 5.48-5.69) after adjusting for atrazine groundwater concentration and the county socio-economic status. While these findings do not indicate a causal relationship, because other contaminants or cancer risk factors have not been accounted for, they suggest that atrazine and nitrate may pose a risk relative to the genesis of pediatric brain and CNS cancers, leukemia, and lymphoma.

Assessment of Pediatric Cancer and Its Relationship to Environmental Contaminants: An Ecological Study in Idaho.

The primary aim of this study was to determine the degree to which a multivariable principal component model based on several potentially carcinogenic metals and pesticides could explain the county-level pediatric cancer rates across Idaho. We contend that human exposure to environmental contaminants is one of the reasons for increased pediatric cancer incidence in the United States. Although several studies have been conducted to determine the relationship between environmental contaminants and carcinogenesis among children, research gaps exist in developing a meaningful association between them. For this study, pediatric cancer data was provided by the Cancer Data Registry of Idaho, concentrations of metals and metalloids in groundwater were collected from the Idaho Department of Water Resources, and pesticide use data were collected from the United States Geological Survey. Most environmental variables were significantly intercorrelated at an adjusted P-value <0.01 (97 out of 153 comparisons). Hence, a principal component analysis was employed to summarize those variables to a smaller number of components. An environmental burden index (EBI) was constructed using these principal components, which categorized the environmental burden profiles of counties into low, medium, and high. EBI was significantly associated with pediatric cancer incidence (P-value <0.05). The rate ratio of high EBI profile to low EBI profile for pediatric cancer incidence was estimated as 1.196, with lower and upper confidence intervals of 1.061 and 1.348, respectively. A model was also developed in the study using EBI to estimate the county-level pediatric cancer incidence in Idaho (Nash-Sutcliffe Efficiency = 0.97).

A potential pesticides exposure index (PPEI) for developing countries: Applied in a transboundary basin.

The potential risk of pesticide exposure in developing countries needs further study as data are limited and simple tools to assess the risks on human health and the environment caused by pesticides are lacking. This article introduces a potential pesticides exposure index (PPEI) as a modeling tool to assess the risk of human and environmental pesticide exposure in agricultural basins. The PPEI is based on a number of factors including: human population centers and their proximity to agricultural crops, the toxicological properties of pesticides, and their application frequency. The index was applied to a region in southern Ecuador (approximately 7200 km2 ) where corn, rice, and sugarcane are the predominant crops, and where hot spots with the highest vulnerability to pesticide residues were identified. Of the total of 5326 neighborhoods for the entire study area, 1030 had high, 1124 had medium, and 1009 had low PPEI scores. Among the practical uses of PPEI are to help to assist regulatory agencies and academics evaluate the effects of land use policies on pesticide vulnerability. Also, it can be easily expanded to include other parameters, such as data from other agricultural crops, or frequency of pesticide application. The PPEI can be a valuable indicator of risk of pesticide exposure, as it is reliable and applicable to developing countries, where data and resources are limited. Integr Environ Assess Manag 2022;18:187-197. © 2021 SETAC.

Investigation of relationships between fecal contamination, cattle grazing, human recreation, and microbial source tracking markers in a mixed-land-use rangeland watershed.

The United States National Forests are mixed-use lands that support human recreation and cattle grazing. Overuse by humans or cattle, however, can lead to the fecal contamination of local waterways. Until recently, the source of these contaminants was a subject of conjecture; however, microbial source tracking tools have become widely used and are proving to be a valid methodology to identify the contamination source. This study aims to analyze and model the quantity and sources of fecal contamination in the Mink Creek watershed in southeastern Idaho. The U.S. Forest Service Caribou-Targhee National Forest (USFS) manages this watershed. Previous research has indicated that some localities within the watershed exceed US EPA standards for coliform bacteria. In 2019, water samples were collected before livestock began grazing and throughout the spring, summer, and fall after livestock grazing had ended. Fourteen sites were sampled seven times during the field season, allowing the water to be analyzed for total coliforms and E. coli bacteria. Microbial source tracking techniques using Bacteroides bacteria, which are known to live in specific digestive tracks, were used to identify the source of E. coli at each sampling location. The analysis indicated that E. coli counts exceeded state regulatory limits 35% of the time. These exceedances were associated with DNA source tracking markers for humans (58.8%), cattle (5.9%), or both cattle and humans (5.9%). Unknown sources were responsible for the Bacteroides bacteria 29.4% of the time. A statistical model was developed to estimate E. coli using the datasets of microbial source tracking measures, the presence or absence of humans, cattle, the proximity of the sampling date to a holiday, and other seasonal factors. The resulting model showed good performance indices at all the 14 sites based on a K-fold cross-validation scheme (R2 = 0.83 and NSE = 0.69). The results demonstrated that E. coli exceedances have a close association with human recreation and unknown sources and negatively influenced by dissolved oxygen.

Biotransport of persistent organic pollutants in the southern Hemisphere by invasive Chinook salmon (Oncorhynchus tshawytscha) in the rivers of northern Chilean Patagonia, a UNESCO biosphere reserve.

Biotransport is often associated with migration patterns of species, including large, anadromous salmonids. Several studies have reported biotransport of persistent organic pollutants in the Northern Hemisphere, but there is no published information on biotransport ocurring south of the equator. Chile's Patagonia is one of the last largely intact natural areas in the world. The objective of this study was to determine whether persistent organic pollutants are transported by the invasive Pacific Chinook salmon (O. tshawytscha) from the Pacific Ocean to Chilean Patagonia. Samples of juvenile and adult Chinook salmon were analyzed for polychlorinated biphenyls, pesticides and polybrominated diphenyl ethers. The results revealed that concentrations of POPs in adults migrating into Patagonian rivers were significantly higher than those found in juveniles migrating seaward. A mass balance analysis indicates that Chinook salmon are a source of persistent organic pollutants to Chilean Patagonia inland waters. Capsule: Biotransport of Persistent Organic Pollutants (POPs) by Chinook salmon (O. tshawytscha) from the Pacific Ocean to Chilean Patagonia has been confirmed by mass balance of POPs.

Salinity modulates biochemical and histopathological changes caused by silver nanoparticles in juvenile Persian sturgeon (Acipenser persicus).

The objective of this study was to evaluate the effect of salinity on the acute and sub-chronic toxicity of silver nanoparticles (AgNPs) in Persian sturgeon. This was evaluated by exposing Persian sturgeon to AgNPs in three salinities: freshwater (F: 0.4 ppt), brackish water 1 (B1: 6 ± 0.2 ppt), and brackish water 2 (B2: 12 ± 0.3 ppt) for 14 days, which was followed by analysis of alterations in plasma chemistry and histopathology of the gills, liver, and intestine. Values of 96-h median lethal concentration (LC50) were calculated as 0.89 mg/L in F, 2.07 mg/L in B1, and 1.59 mg/L in B2. After sub-chronic exposures, plasma cortisol, glucose, potassium, and sodium levels illustrated no significant changes within each salinity level. In F, 0.2 mg/L AgNP caused the highest levels of alkaline phosphatase and osmolality levels. In B1, 0.6 mg/L AgNP induced the highest level of alkaline phosphatase and elevated plasma osmolality was recorded in all AgNP-exposed treatments in comparison with the controls. The B2 treatment combined with 0.6 mg/L AgNP significantly reduced plasma chloride level. The results showed elevating salinity significantly increased osmolality, chloride, sodium, and potassium levels of plasma in the fish exposed to AgNPs. The abundance of the tissue lesions was AgNP concentration-dependent, where the highest number of damages was observed in the gills, followed by liver and intestine, respectively. The histopathological study also confirmed alterations such as degeneration of lamella, lifting of lamellar epithelium, hepatic vacuolation, pyknotic nuclei, and cellular infiltration of the lamina propria elicited by AgNPs in the gills, liver, and intestine of Persian sturgeon. In conclusion, the stability of AgNPs in aquatic environments can be regulated by changing the salinity, noting that AgNPs are more stable in low salinity waters.

Assessment of Gene Expression Biomarkers in the Chilean Pencil Catfish, Trichomycterus areolatus, from the Choapa River Basin, Coquimbo Chile.

The objective of this study was to describe changes in the gene expression in the Chilean catfish, Trichomycterus areolatus, based on their geographic location within the Choapa River. Genes of choice included those that are biomarkers of exposure to metals, oxidative stress, and endocrine disruption. Male and female T. areolatus were sampled from four sites in January 2015 differently impacted by human activities. In males, but not females, hepatic gene expression of heat shock protein (HSP70) and cytochrome P450 1A (CYP1A) were significantly elevated at the site adjacent to the small city of Salamanca, relative to the other sites. In females, hepatic HSP70, the aryl hydrocarbon receptor (AHR), and the estrogen responsive genes, vitellogenin (VTG) and estrogen receptor alpha (ERα), were significantly lower at the site located furthest downstream. A similar downstream pattern of lower expression levels also was found in ovarian tissue for the genes, HSP70 and ERα. Gill gene expression showed a unique pattern in females as levels of metallothionein were elevated at the site furthest downstream. While analytical chemistry of water samples provided limited evidence of agrichemical contamination, the gene expression data are consistent with an exposure to agrichemicals and metals. T. areolatus may be a valuable sentinel organism and its use as a bioindicator species in some rivers within Chile can provide considerable insight, particularly in situations analytical chemistry is limited by environmental constraints.

Pesticide contamination drives adaptive genetic variation in the endemic mayfly Andesiops torrens within a semi-arid agricultural watershed of Chile.

Agrichemical contamination can provoke evolutionary responses in freshwater populations. It is a particularly relevant issue in semi-arid regions due to the sensitivity of endemic species to pollutants and to interactions with temperature stress. This paper investigates the presence of pesticides in rivers within a semi-arid agricultural watershed of Chile, testing for their effects on population genetic characteristics of the endemic mayfly Andesiops torrens (Insecta, Ephemeroptera). Pesticides were detected in sediment samples in ten out of the 30 sites analyzed throughout the upper part of the Limarí watershed. To study the evolutionary impact of such contamination on A. torrens, we used a genome-wide approach and analyzed 2056 single nucleotide polymorphisms (SNPs) loci in 551 individuals from all sites. Genetic differentiation was weak between populations, suggesting high gene flow across the study area. While we did not find evidence of pesticide effects on genetic diversity nor on population differentiation, the allele frequency of three outlier SNP loci correlated significantly with pesticide occurrence. Interrogation of genomic resources indicates that two of these SNPs are located within functional genes that encode for the low-density lipoprotein receptor-related protein 2 and Dumpy, both potentially involved in insect cuticle resistance processes. Such genomic signatures of local adaptation are indicative of past adverse effects of pesticide exposure on the locally adapted populations. Our results reveal that A. torrens is sensitive to pesticide exposure, but that a high gene flow may confer resilience to contamination. This research supports the contention that A. torrens is an ideal model organism to study evolutionary responses induced by pesticides on non-target, endemic species.

Assessing the Accuracy of Citizen Scientist Reported Measurements for Agrichemical Contaminants.

Citizen science is a research tool capable of addressing major environmental challenges, including contamination of water resources by agrichemicals, such as nutrients and pesticides. The objectives of this study were (1) to identify the proportion of accurate observations by citizen scientists using rapid assessment water quality tools, and (2) to characterize how a user's prior experience with water quality tools was associated with the accuracy of citizen scientists. To achieve these objectives, we conducted group testing with over 136 citizen scientists and compared their results from water quality testing of water samples to results obtained using laboratory analytical methods. Following brief training, we observed that accuracy of reported results varies based on the user's experience level where experienced and expert users shared consistent and reliable measurements. Where erroneous measures were reported, citizen scientists tend to overestimate contaminant concentrations when using colorimetric water quality tools. Additionally, we identified differences in accuracy related to the types of water quality assessment tools used by citizen scientists from each experience group. This study demonstrates the importance of evaluating participant background experience in designing citizen science campaigns.

The Fate of Synthetic and Endogenous Hormones Used in the US Beef and Dairy Industries and the Potential for Human Exposure.

PURPOSE OF REVIEW: Growth-enhancing chemicals used by the beef and dairy industries may be bioavailable to humans via milk, meat, and other environmental matrices. This review evaluates the potential for environmental transport and bioavailability of the active chemical to humans. RECENT FINDINGS: Bovine somatostatin is detectable in milk; however, there is no evidence that the protein persists in the environment nor that it is active in humans. In contrast, steroids are transported through milk and meat to humans where they may exert biological activity. Furthermore, environmental matrices such as raw water and dust may also allow for the environmental transport and bioavailability of steroids to humans. Endogenous and exogenous steroids can be found in the meat, milk, and waste materials produced by cattle. While the concentrations may be low, exposure to these matrices, most notably dairy products made with whole milk, can be a source of exogenous steroids to humans.

Using Watershed Boundaries to Map Adverse Health Outcomes: Examples From Nebraska, USA.

In 2009, a paper was published suggesting that watersheds provide a geospatial platform for establishing linkages between aquatic contaminants, the health of the environment, and human health. This article is a follow-up to that original article. From an environmental perspective, watersheds segregate landscapes into geospatial units that may be relevant to human health outcomes. From an epidemiologic perspective, the watershed concept places anthropogenic health data into a geospatial framework that has environmental relevance. Research discussed in this article includes information gathered from the literature, as well as recent data collected and analyzed by this research group. It is our contention that the use of watersheds to stratify geospatial information may be both environmentally and epidemiologically valuable.

Comparing the effects of atrazine and an environmentally relevant mixture on estrogen-responsive gene expression in the northern leopard frog and the fathead minnow.

In Nebraska, fish are exposed to herbicides in agricultural runoff. The study objectives were to determine 1) if fathead minnows and northern leopard frogs exposed to atrazine experience alterations in gene expression, and 2) whether these changes are elicited by a simulated herbicide mixture. Following a 7-d exposure to atrazine, female minnows were defeminized, whereas male frogs were feminized. The mixture did not elicit statistically significant effects in either species. Environ Toxicol Chem 2018;37:1182-1188. © 2018 SETAC.

Response and recovery of fathead minnows (Pimephales promelas) following early life exposure to water and sediment found within agricultural runoff from the Elkhorn River, Nebraska, USA.

Agricultural runoff is a non-point source of chemical contaminants that are seasonally detected in surface water and sediments. Agrichemicals found within seasonal runoff can elicit endocrine disrupting effects in organisms as adults, juveniles and larvae. The objectives of this study were (1) to determine if exposure to water, sediment or the water-sediment combination collected from an agricultural runoff event was responsible for changes in endocrine-responsive gene expression and development in fathead minnow larvae, and (2) whether such early life exposure leads to adverse effects as adults. Larvae were exposed during the first month post-hatch to water and sediment collected from the Elkhorn River and then allowed to depurate in filtered water until reaching sexual maturity, exemplifying a best-case recovery scenario. Gas chromatography mass spectrometry (GC/MS) analysis of the water and sediment samples detected 12 pesticides including atrazine, acetochlor, metolachlor and dimethenamid. In minnow larvae, exposure to river water upregulated androgen receptor gene expression whereas exposure to the sediment downregulated estrogen receptor α expression. Adult males previously exposed to both water and sediment were feminized through the induction of an ovipositor structure whereas no impacts were observed in other reproductive or sex characteristic endpoints for either sex based on exposure history. Results from this study indicate that both water and sediments found in agricultural runoff elicit responses from minnow larvae, and larvae can recover following early life exposure under a best-case scenario.