12
Mar
Study Shows the Prevalence of Toxic Pesticide Leaching into Groundwater Reserves Is an International Concern
(Beyond Pesticides, March 12, 2024) A study released in Science of the Total Environment unpacks the threat of emerging chemicals of concern (CECs), including toxic pesticides, in the groundwater of Tunisia. Researchers highlight that the impact of pesticide drift and leaching into groundwater reserves is not siloed to the Middle East and North Africa (MENA) region, but a key concern for most industrialized countries, including the United States. Authors of this study build on literature of CECs already conducted in the region that have broader implications for the spillover effects of pesticide regulation in broader contexts. This descriptive study and accompanying Environmental Risk Assessment (ERA) demonstrate the urgency of Beyond Pesticides’ mission to ban toxic petrochemical pesticides by 2032 because of the pervasiveness of toxic residues, be it pesticides, antibiotics, or other substances, from groundwater systems to human bodies.
The researchers performed the tests in thirteen wells in the Grombalia shallow aquifer, an area of northeast Tunisia that feeds into the Wadi El Bay watershed, which is defined as a “high population density [with] intensive agricultural activity [in ‘one of the most polluted areas in Tunisia’].†The researchers gathered data “during two seasons and were analyzed with two high resolution mass spectrometry approaches: target and suspect screening. The latter was screening banned pesticides.†For more information on the suspect screening approach for pesticide analysis, see Subsection 2.4 under the Materials and Methods.
The researchers identified 20 target pesticides in this study: Anabasine, atrazine, bendiocarb, bentranil, carbaryl, carbofuran, DEET, desethylatrazine, desethylterbuthylazine, dimethomorph, fenfuram, imidacloprid, isoproturon, methfuroxam, mexacarbate, propamocarb, propoxur, pyroquilon, spiroxamine, and terbuthylazine. Table 2 delineates the concentrations of the most frequently detected pesticides in groundwater samples, which include DEET, mexacarbate, propoxur, desethylatrazine, and terbuthylazine. The authors are particularity concerned with the presence of “several carbamate insecticides…due to their acute and chronic toxicity.†The main source of carbamate insecticides are from agricultural use, which is not surprising given that the Grombalia region’s economy is mainly based on citrus: “77.3 percent of the irrigated area [in this region] is planted with citrus [].â€
“The most frequently quantified pesticides belong to the family of triazine herbicides and carbamate insecticides. Triazines have been highly used on several agricultural crops. The occurrence of triazine herbicides in groundwater has been found very commonly [] with most likely no potential human-health concerns at the observed levels of detection [],†authors report in Section 3.1.2 on the results and discussion subsection on pesticides. According to the report: “The frequent detection of triazines can also be expressed as a function of their groundwater ubiquity score (GUS) index, used to predict the behavior of pollutants in groundwater. Triazines are the compounds with the highest GUS index and detection frequency, indicating their high leachability. Atrazine and its degradation product desethylatrazine are by far the most abundant herbicides detected in shallow groundwater []. Atrazine was not detected in the sampling sites, while its metabolite desethylatrazine was detected in 13 samples in both sampling campaigns []. Some researchers have shown that pesticide metabolites are often detected in groundwater at higher concentrations compared to parent compounds [] and that their presence can be more toxic than their parents. []†This last line on pesticide metabolites is consistent with findings from numerous studies which demonstrate the relationship between groundwater and pesticide residue exposure and infiltration in the United States, for example, “90 percent of Americans having at least one pesticide biomarker (includes parent compound and metabolites) in their body,†according to the Centers for Disease Control and Prevention.
Beyond the focus on pesticides, the study also documents the occurrence of CECs, which include “commonly prescribed drugs [‘antimicrobials, analgesics, anti-inflammatories’], artificial sweeteners [sucralose], insecticides [fipronil], and UV filters.†Sixty-nine compounds of CECS and one transformation product [metabolites or degradation products of the precursor analyte’] and 20 pesticides were detected per well, “ranging between 43 and 7384 ng L−1 and 7.3 and 80 ng L−1, respectively. The unit ng L-1 refers to one nanogram of a substance per liter of water.
Researchers in this study found it pertinent to study toxic substance exposure in Tunisian groundwater since a vast majority of the population accesses water resources through wells linked to aquifers. A 2023 Gallup poll indicates a record dissatisfaction with water quality across 81 percent of the population, particularly in southern regions of the country. “Industrial waste from phosphate mining—phosphogypsum—has led to spikes in cancer rates, infertility, and miscarriage in the region. Once famed for its thriving marine ecosystems, fish stocks have plummeted. Groundwater has been polluted, with diminishing reserves for households.†One of the reasons these researchers focused on an area in northeast Tunisia was because of the lack of existing data regarding toxic substance residues in groundwater reserves generally.
There is extensive reporting by Beyond Pesticides on the human, wildlife, and ecological health implications of pesticide leaching into groundwater. For instance, marine ecosystems along the U.S. West Coast are threatened by forest management practices that permit the use of pesticides including certain herbicides (indaziflam, hexazinone, and atrazine), fungicides (fluopicolide and pyraclostrobin), and insecticides (bifenthrin and permethrin). In Arizona, the State Auditor General reported deep concern over the insufficient amount of groundwater monitoring for pesticides by the Arizona Department of Environmental Quality between 2017 and 2021 which flew in the face of legal requirements.
Beyond Pesticides continues to call on Secretary of Interior Deb Haaland to expand USGS mapping of pesticide use and monitoring and inform the U.S. Environmental Protection (EPA) Administrator Michael Regan that pesticides shown to contaminate rivers and streams must be banned. The regulation of and rulemaking around pesticide infiltration in groundwater is more complicated in the aftermath of Sackett v. EPA (2023), a Supreme Court case that limited EPA’s authority to protect critical wetland ecosystems through a narrower definition of, “Waters of the United States (WOTUS). In the 5-4 SCOTUS decision, regulation of groundwater (including protections against pesticide residue) was undermined once WOTUS was defined by the language, “continuous surface connection to bodies.â€
Beyond the patchwork of state and national law that impacts water and pesticide regulation, investing in the protection of organic agricultural and land management principles is a critical approach to prevent the overwhelmingly majority of toxic petrochemical pesticides from leaching into groundwater in the first place. Beyond Pesticides affirms the decades of advocacy that went into establishing organic agriculture standards through the Organic Foods Production Act of 1990. This legislation established mechanisms for compliance, oversight, and enforcement of the national List of Allowed and Prohibited Substances to protect the public against toxic pesticides that EPA permits acceptable use in conventional, industrial agriculture. See Keeping Organic Strong as the National Organic Standards Board will offer the public the opportunity to suggest changes to the National Organic Program through public hearings, comment periods, and written testimonials in April.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.Â
Source: Science of the Total Environment
My heart hopes SO much that the RIGHT thing is done so that ALL living can live their life.
March 13th, 2024 at 6:31 pm