When enough data are not enough to enact policy: The failure to ban chlorpyrifos

Diabrotica v. virgifera Seems Not Affected by Entomotoxic Protease Inhibitors from Higher Fungi

Certain soil insects, such as the root-damaging larvae of the maize pest Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae), are increasingly difficult to control because of recent bans of some insecticides. An alternative and safer approach may be the development of biopesticides based on entomotoxic defense proteins of higher fungi. Many of these potentially interesting proteins are protease inhibitors, and some have been shown to adversely affect insects. We examined the effects of the cysteine protease inhibitors macrocypin 1, 3, and 4 from Macrolepiota procera, clitocypin from Clitocybe nebularis, and cocaprin 1 and the serine protease inhibitor cospin 1 from Coprinopsis cinerea on D. v. virgifera. We confirmed the inhibition by mycocypins of the cysteine catalytic-type proteolytic activities in gut extracts of larvae and adults. The inhibition of pGlu-Phe-Leu-hydrolyzing activity was stronger than that of Z-Phe-Arg-hydrolyzing activity. Mycocypins and cospin resisted long-term proteolytic digestion, whereas cocaprin 1 was digested. Bioassays with overlaid artificial diet revealed no effects of proteins on neonatal mortality or stunting, and no effects on adult mortality. Immersion of eggs in protein solutions had little effect on egg hatching or mortality of hatching neonates. Microscopic analysis of the peritrophic matrix and apical surface of the midguts revealed the similarity between larvae of D. v. virgifera and the chrysomelid Leptinotarsa decemlineata, which are sensitive to these inhibitors. The resistance of D. v. virgifera to fungal protease inhibitors is likely due to effective adaptation of digestive enzyme expression to dietary protease inhibitors. We continue to study unique protein complexes of higher fungi for the development of new approaches to pest control.

In situ chlorpyrifos (CPF) degradation by Acrobeloides maximus: Insights from chromatographic analysis

The objective of this study was to evaluate the efficiency of nematodes in zooremediation of chlorpyrifos (CPF), an organophosphate pesticide. The nematode population Acrobeloides maximus (A. maximus) was employed for bioremediation, converting CPF into non-toxic residues. Optimal growth conditions for mass production of A. maximus were achieved by maintaining a temperature of 25 °C, pH 8, and supplementing the culture medium with plant nutrients. The nematodes were then immobilized within sodium alginate beads. The efficacy of the degradation process was assessed using various analytical techniques, including UV-Visible spectroscopy, HPTLC, FTIR, and LC-MS, confirming the successful breakdown of CPF. The bioreactor demonstrated a complete degradation efficiency of CPF exceeding 99%. Additionally, LC-MS analysis was conducted to elucidate the degradation pathway based on the formation of intermediates. These results underscore the potential of A. maximus as a sustainable organism for addressing environmental contamination arising from CPF pesticide.

The regulation of endocrine-disrupting chemicals to minimize their impact on health

Endocrine-disrupting chemicals (EDCs) are substances generated by human industrial activities that are detrimental to human health through their effects on the endocrine system. The global societal and economic burden posed by EDCs is substantial. Poorly defined or unenforced policies can increase human exposure to EDCs, thereby contributing to human disease, disability and economic damage. Researchers have shown that policies and interventions implemented at both individual and government levels have the potential to reduce exposure to EDCs. This Review describes a set of evidence-based policy actions to manage, minimize or even eliminate the widespread use of these chemicals and better protect human health and society. A number of specific challenges exist: defining, identifying and prioritizing EDCs; considering the non-linear or non-monotonic properties of EDCs; accounting for EDC exposure effects that are latent and do not appear until later in life; and updating testing paradigms to reflect 'real-world' mixtures of chemicals and cumulative exposure. A sound strategy also requires partnering with health-care providers to integrate strategies to prevent EDC exposure in clinical care. Critical next steps include addressing EDCs within global policy frameworks by integrating EDC exposure prevention into emerging climate policy.

Insight into the environmental fate, hazard, detection, and sustainable degradation technologies of chlorpyrifos-an organophosphorus pesticide

Pesticides play a critical role in terms of agricultural output nowadays. On top of that, pesticides provide economic support to our farmers. However, the usage of pesticides has created a public health issue and environmental hazard. Chlorpyrifos (CPY), an organophosphate pesticide, is extensively applied as an insecticide, acaricide, and termiticide against pests in various applications. Environmental pollution has occurred because of the widespread usage of CPY, harming several ecosystems, including soil, sediment, water, air, and biogeochemical cycles. While residual levels in soil, water, vegetables, foodstuffs, and human fluids have been discovered, CPY has also been found in the sediment, soil, and water. The irrefutable pieces of evidence indicate that CPY exposure inhibits the choline esterase enzyme, which impairs the ability of the body to use choline. As a result, neurological, immunological, and psychological consequences are seen in people and the natural environment. Several research studies have been conducted worldwide to identify and develop CPY remediation approaches and its derivatives from the environment. Currently, many detoxification methods are available for pesticides, such as CPY. However, recent research has shown that the breakdown of CPY using bacteria is the most proficient, cost-effective, and sustainable. This current article aims to outline relevant research events, summarize the possible breakdown of CPY into various compounds, and discuss analytical summaries of current research findings on bacterial degradation of CPY and the potential degradation mechanism.

Exposures to pesticides and risk of cancer: Evaluation of recent epidemiological evidence in humans and paths forward

Knowledge of the role in cancer etiology of environmental exposures as pesticides is a prerequisite for primary prevention. We review 63 epidemiological studies on exposure to pesticides and cancer risk in humans published from 2017 to 2021, with emphasis on new findings, methodological approaches, and gaps in the existing literature. While much of the recent evidence suggests causal relationships between pesticide exposure and cancer, the strongest evidence exists for acute myeloid leukemia (AML) and colorectal cancer (CRC), diseases in which the observed associations were consistent across several studies, including high-quality prospective studies and those using biomarkers for exposure assessment, with some observing dose-response relationships. Though high-quality studies have been published since the IARC monograph on organophosphate insecticides in 2017, there are still gaps in the literature on carcinogenic evidence in humans for a large number of pesticides. To further knowledge, we suggest leveraging new techniques and methods to increase sensitivity and precision of exposure assessment, incorporate multi-omics data, and investigate more thoroughly exposure to chemical mixtures. There is also a strong need for better and larger population-based cohort studies that include younger and nonoccupationally exposed individuals, particularly during developmental periods of susceptibility. Though the existing evidence has limitations, as always in science, there is sufficient evidence to implement policies and regulatory action that limit pesticide exposure in humans and, hence, further prevent a significant burden of cancers.

The Pediatrician's Role in Protecting Children from Environmental Hazards

Children suffer disproportionately from disease and disability due to environmental hazards, for reasons rooted in their biology. The contribution is substantial and increasingly recognized, particularly due to ever-increasing awareness of endocrine disruption. Regulatory actions can be traced directly to reductions in toxic exposures, with tangible benefits to society. Deep flaws remain in the policy framework in industrialized countries, failing to offer sufficient protection, but are even more limited in industrializing nations where the majority of chemical production and use will occur by 2030. Evidence-based steps for reducing chemical exposures associated with adverse health outcomes exist and should be incorporated into anticipatory guidance.

Intermittent exposure to chlorpyrifos results in cardiac hypertrophy and oxidative stress in rats

Forbidden in some countries due to its proven toxicity to humans, chlorpyrifos (CPF) still stands as an organophosphate pesticide (OP) highly used worldwide. Cardiotoxicity assessment is an unmet need in pesticide regulation and should be deeply studied through different approaches to better inform and generate an appropriate regulatory response to OP use. In the present study, we used our 4-week intermittent OP exposure model in rats to address the CPF effects on cardiac morphology allied with cardiovascular functional and biomolecular evaluation. Rats were intermittently treated with CPF at doses of 7 mg/kg and 10 mg/kg or saline (i.p.) and assessed for cardiac morphology (cardiomyocyte diameter and collagen content), cardiopulmonary Bezold-Jarisch reflex (BJR) function, cardiac autonomic tone, left ventricle (LV) contractility, cardiac expression of NADPH oxidase (Nox2), catalase (CAT), superoxide dismutase 1 (SOD1), superoxide dismutase 2 (SOD2) and cardiac levels of advanced oxidation protein products (AOPP) and thiobarbituric acid reactive substances (TBARS). Plasma butyrylcholinesterase (BuChE) and brainstem acetylcholinesterase (AChE) were also measured. Intermittent exposure to CPF induced cardiac hypertrophy, increasing cardiomyocyte diameter and collagen content. An impairment of cardioinhibitory BJR responses and an increase in cardiac vagal tone were also observed in CPF-treated animals without changes in LV contractility. CPF exposure increased cardiac Nox-2, CAT, SOD1, and TBARS levels and inhibited plasma BuChE and brainstem AChE activities. Our data showed that intermittent exposure to CPF induces cardiac hypertrophy together with cardiovascular reflex impairment, imbalance of autonomic tone and oxidative stress, which may bring significant cardiovascular risk to individuals exposed to OP compounds seasonally.

Molecular Mechanisms of Acute Organophosphate Nephrotoxicity

Organophosphates (OPs) are toxic chemicals produced by an esterification process and some other routes. They are the main components of herbicides, pesticides, and insecticides and are also widely used in the production of plastics and solvents. Acute or chronic exposure to OPs can manifest in various levels of toxicity to humans, animals, plants, and insects. OPs containing insecticides were widely used in many countries during the 20th century, and some of them continue to be used today. In particular, 36 OPs have been registered in the USA, and all of them have the potential to cause acute and sub-acute toxicity. Renal damage and impairment of kidney function after exposure to OPs, accompanied by the development of clinical manifestations of poisoning back in the early 1990s of the last century, was considered a rare manifestation of their toxicity. However, since the beginning of the 21st century, nephrotoxicity of OPs as a manifestation of delayed toxicity is the subject of greater attention of researchers. In this article, we present a modern view on the molecular pathophysiological mechanisms of acute nephrotoxicity of organophosphate compounds.

Characterization of organophosphate pesticide sorption of potato peel biochar as low cost adsorbent for chlorpyrifos removal

There has been a growing interest in the scientific world in the production of biochar from natural organic wastes as potential sustainable precursors for bioremediation. Potato peel biochar was produced by slow pyrolysis method under oxygen-limited conditions and used as bio adsorbent in bioremediation of commercial pesticide having Chlorpyrifos as an active component. Chlorpyrifos is an organophosphate pesticide, highly neurotoxic, and primarily targets the central nervous system of pests and insects. The excess residues of chlorpyrifos are hazardous to environmental flora and fauna. Chlorpyrifos was treated against biochar at varying physical parameters and further optimized by using response surface methodology through Box-Behnken design (BBD). 72.06% of pesticide removal was observed post 24 h of treatment against a pesticide concentration of 1346.85 μg/ml with a biochar concentration of 1.04 mg/ml under room temperature at pH 5.04. Biochar was characterized by proximate and ultimate analysis, FTIR, and SEM-EDX. Characterization by SEM-EDX showed the surface morphology and minerals on the peel and biochar. Microgram of potato peel shows pores of larger size than biochar having many cavities with different dimensions. In the plant system, growth morphology, nutritional status, polyphenols, total antioxidant content, and free radical scavenging activity were assessed. Enhancement in presence of biochar was recorded in growth morphology and plant biomolecules including photosynthetic pigments. Better translocation of the nutrient is recorded in biochar treated plants, as evidenced by the low amount of carbohydrate and protein in treated leaves. Biocompatibility assessment of chlorpyriphos in fish erythrocytes showed 43.26% hemolysis by pesticide-treated biochar. The practical use of this approach can also be best utilized if applied to those geographical regions where the soil pH is acidic. Biochar is a marketable bio-product, which can have a positive impact in agriculture, industries, and the energy sector creating a bio-based economy with reduced environmental pollution.

A review on the microbial degradation of chlorpyrifos and its metabolite TCP

Chlorpyrifos (CPF) falls under the category of organophosphorus pesticides which are in huge demand in the agricultural sector. Overuse of this pesticide has led to the degradation of the quality of terrestrial and aquatic life. The chemical is moderately persistent in the environment but its primary metabolite 3,5,6-trichloro-2-pyridinol (TCP) is comparatively highly persistent. Thus, it is important to degrade the chemical and there are many proposed techniques of degradation. Out of which bioremediation is considered to be highly cost-effective and efficient. Many previous studies have attempted to isolate appropriate microbial strains to degrade CPF which established the fact that chlorine atoms released while mineralising TCP inhibits further proliferation of microorganisms. Thus, it has been increasingly important to experiment with strains that can simultaneously degrade both CPF and TCP. In this review paper, the need for degrading CPF specifically the problems related to it has been discussed elaborately. Alongside these, the metabolism pathways undertaken by different kinds of microorganisms have been included. This paper also gives a detailed insight into the potential strains of microorganisms which has been confirmed through experiments conducted previously. It can be concluded that a wide range of microorganisms has to be studied to understand the possibility of applying bioremediation in wastewater treatment to remove pesticide residues. In addition to this, in the case of recalcitrant pesticides, options of treating it with hybrid techniques like bioremediation clubbed with photocatalytic biodegradation can be attempted.

Organophosphate pesticides and progression of chronic kidney disease among children: A prospective cohort study

BACKGROUND

Growing evidence suggests that exposure to environmental chemicals, such as pesticides, impacts renal function and chronic kidney disease (CKD). However, it is not clear if pesticides may affect CKD progression and no studies exist in children.

OBJECTIVES

The objective of this study was to examine associations between serially measured urinary OP pesticide metabolites and clinical and laboratory measures of kidney function over time among children with CKD.

METHODS

This study used data on 618 participants enrolled in the CKD in Children study (CKiD), a cohort study of pediatric CKD patients from the US and Canada. Children were followed over an average of 3.0 years (standard deviation (SD) = 1.6) between 2005 and 2015. In serially collected urine samples over time, six nonspecific dialkyl phosphate (DAP) metabolites of OP pesticides were measured. Biomarkers of tubular injury (kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL)) and oxidant stress (8-hydroxy-2'-deoxyguanosine (8-OHdG) and F2-isoprostane) were determined in the same specimens. Estimated glomerular filtration rate (eGFR), proteinuria, and blood pressure were assessed annually.

RESULTS

DAPs were associated with increased KIM-1 and 8-OHdG throughout follow-up. A standard deviation increase in ∑diethyl metabolites was associated with increases of 11.9% (95% Confidence Interval (CI): 4.8%, 19.4%) and 13.2% (95% CI: 9.3%, 17.2%) in KIM-1 and 8-OHdG over time, respectively. DAPs were associated with lower eGFR at baseline and higher eGFR over subsequent years.

CONCLUSIONS

These findings provide preliminary evidence suggesting that urinary DAP metabolites are associated with subclinical kidney injury among children with CKD, which may signal the potential for clinical events to manifest in the future. The results from this study are significant from both a clinical and public health perspective, given that OP pesticide exposure is a modifiable risk factor.

Neurobehavioral anomalies in zebrafish after sequential exposures to DDT and chlorpyrifos in adulthood: Do multiple exposures interact?

A sequence of different classes of synthetic insecticides have been used over the past 70 years. Over this period, the widely-used organochlorines were eventually replaced by organophosphates, with dichlorodiphenyltrichloroethane (DDT) and chlorpyrifos (CPF) as the principal prototypes. Considerable research has characterized the risks of DDT and CPF individually, but little is known about the toxicology of transitioning from one class of insecticides to another, as has been commonplace for agricultural and pest control workers. This study used adult zebrafish to investigate neurobehavioral toxicity following 5-week chronic exposure to either DDT or CPF, to or their sequential exposure (DDT for 5 weeks followed by CPF for 5 weeks). At the end of the exposure period, a subset of fish were analyzed for brain cholinesterase activity. Behavioral effects were initially assessed one week following the end of the CPF exposure and again at 14 months of age using a behavioral test battery covering sensorimotor responses, anxiety-like functions, predator avoidance and social attraction. Adult insecticide exposures, individually or sequentially, were found to modulate multiple behavioral features, including startle responsivity, social approach, predator avoidance, locomotor activity and novel location recognition and avoidance. Locomotor activity and startle responsivity were each impacted to a greater degree by the sequential exposures than by individual compounds, with the latter being pronounced at the early (1-week post exposure) time point, but not 3-4 months later in aging. Social approach responses were similarly impaired by the sequential exposure as by CPF-alone at the aging time point. Fleeing responses in the predator test showed flee-enhancing effects of both compounds individually versus controls, and no additive impact of the two following sequential exposure. Each compound was also associated with changes in recognition or avoidance patterns in a novel place recognition task in late adulthood, but sequential exposures did not enhance these phenotypes. The potential for chemical x chemical interactions did not appear related to changes in CPF metabolism to the active oxon, as prior DDT exposure did not affect the cholinesterase inhibition resulting from CPF. This study shows that the effects of chronic adult insecticide exposures may be relevant to behavioral health initially and much later in life, and that the effects of sequential exposures may be unpredictable based on their constituent exposures.

Organophosphate pesticide exposure: Demographic and dietary predictors in an urban pregnancy cohort

Pregnant women are widely exposed to organophosphate (OP) pesticides, which are potentially neurotoxicant for the developing fetus. We aimed to identify principal demographic and dietary predictors of OP pesticide exposure among 450 pregnant women participating in the New York University Children's Health and Environment Study (enrolled 2016-19). Urinary concentrations of six dialkyl phosphate (DAP) metabolites (3 dimethyl (DM) metabolites and 3 diethyl (DE) metabolites) of OP pesticides were determined at three time points across pregnancy. At mid-gestation, the Diet History Questionnaire II was used to assess women's dietary intake over the past year. Demographic characteristics were obtained using questionnaires and/or electronic health records. We used linear mixed models to evaluate the associations of demographic and food groups with DAP metabolite levels, and partial-linear single-index (PLSI) models to analyze the contribution proportions of food groups to DAP metabolite concentrations and the dose-response relationships between them. We observed that pregnant women in NYC had lower levels of OP pesticide metabolites than pregnant populations in Europe, Asia, and other regions in the U.S. Having lower pre-pregnancy body mass index and being Asian, employed, and single were associated with higher DAP metabolite concentrations. Fruit and grain intakes were associated with higher ∑DM, ∑DE, and ∑DAP levels. ∑DE concentrations increased 9.0% (95% confidence interval (CI) = 1.2%, 17.4%) per two-fold increase in dairy consumption, whereas ∑DE concentrations decreased 1.8% (95%CI = -3.1%, -0.4%) per two-fold increase in seafood consumption. The PLSI model indicated that among the food mixture, fruit and grains were the main food groups contributed to higher levels of ∑DAP, while meat contributed to lower levels of ∑DAP. The contribution proportions of fruit, grains, and meat were 18.7%, 17.9%, and 39.3%, respectively. Our results suggest that fruit, grains, and meat are major dietary components associated with OP pesticide exposure in urban pregnant women.

Endocrine disruptor global policy

Over the past several decades, scientific consensus has grown around the concept and evidence for human health impacts from exposure to endocrine disrupting chemicals (EDCs). A series of publications have now demonstrated considerable economic costs of EDC exposure-induced adverse health outcomes. This research has suggested economic burdens in the hundreds of billions, even considering only a small subset of EDCs and health. As of yet, regulatory efforts and policies to protect and decrease human exposure to most EDCs have been insufficient and have not kept pace with the science. Given the overwhelming scientific evidence, referenced throughout this collection, as well as the economic costs of inaction, described here, regulations are clearly needed. The EU and some other countries have taken promising steps towards protective regulation of EDCs, though the response of the US and many other countries has been limited or altogether lacking. Regulatory bodies that have and continue to apply risk-based approaches to regulating EDCs have also failed to consider the complete economic impacts of EDC-related health impacts. In this chapter, we will discuss broad strategies taken to regulate EDCs, examine the approaches currently taken to regulate EDCs in a global context (discussing the strengths and weaknesses of these regulations), discuss the economic costs of EDC exposures (detailing where consideration of health and economic costs could improve regulations), and discuss next steps and novel approaches to adapting existing regulatory frameworks to this class of chemicals.

Agrochemical pesticide production, trade, and hazard: Narrowing the information gap in Colombia

Pesticides are a major tool for the intensification of agriculture, and helped to increase food, feed and biofuel production. Yet, there are persistent concerns about the negative effects of pesticides in human health and the environment, particularly in low and middle income countries (LMICs). Given the lack of information on pesticide exposure and hazard, Colombia exemplifies the need to narrow the information gap on pesticide risk in LMICs. We assessed pesticide hazard in Colombia based on the official toxicity categorization, compared it to more integral international standards, and identified main actions to narrow this information gap. Results showed that Colombia has been a relevant regional actor in pesticide production and trade, reaching almost 75 million kilogrammes and liters sold in 2016. Based on acute toxicity for humans, a quarter of the amount of pesticides sales and imports, and a third of the exports in 2016 ranged from moderately to extremenly toxic. The top-selling agrochemicals in 2016 (glyphosate with 14% of the total sales, chlorpyrifos 7.5% and mancozeb 6.9%) are also commonly used in other countries, reflecting a homogenized global industry. Compared to integral international categorizations, we found that for that year 63% of the pesticides sold with slightly acute toxicity are actually considered highly hazardous pesticides (HHP) for humans or the environment, evidencing the need to use a more integral hazard categorization in the country. Narrowing the information gap in pesticide use and associated risks demands a transparent process of knowledge creation and sharing, including funtional information and monitoring systems. This should be part of an integral assessment and regulation that better defines HHP, their production and trade to reduce pesticide risk while informing a transition towards sustainable food systems.

The science of spin: targeted strategies to manufacture doubt with detrimental effects on environmental and public health

BACKGROUND

Numerous groups, such as the tobacco industry, have deliberately altered and misrepresented knowable facts and empirical evidence to promote an agenda, often for monetary benefit, with consequences for environmental and public health. Previous research has explored cases individually, but none have conducted an in-depth comparison between cases. The purpose of this study was to compile a comprehensive list of tactics used by disparate groups and provide a framework for identifying further instances of manufactured doubt.

METHODS

We examined scholarly books, peer-reviewed articles, well-researched journalism pieces, and legal evidence related to five disparate industries and organizations selected for their destructive impacts on environmental and public health (tobacco, coal, and sugar industries, manufacturers of the pesticide Atrazine, and the Marshall Institute, an institute focused on climate change research, and other scientists from the era that associated with those in the Institute). These documents provided evidence for a list of tactics used to generate pro-industry spin and manufacture doubt about conferred harm. We then identified trends among sets of strategies that could explain their differential use or efficacy.

RESULTS

We recognized 28 unique tactics used to manufacture doubt. Five of these tactics were used by all five organizations, suggesting that they are key features of manufactured doubt. The intended audience influences the strategy used to misinform, and logical fallacies contribute to their efficacy.

CONCLUSIONS

This list of tactics can be used by others to build a case that an industry or group is deliberately manipulating information associated with their actions or products. Improved scientific and rhetorical literacy could be used to render them less effective, depending on the audience targeted, and ultimately allow for the protection of both environmental health and public health more generally.

Qualitative assessment of 27 current-use pesticides in air at 20 sampling sites across Africa

Increasing use of current-use pesticides (CUPs) in Africa raises environmental and public health concerns. But there is a large uncertainty about their occurrence and the composition of pesticide mixtures on this continent. This paper investigates the presence of 27 CUPs in air across 20 sampling sites in Africa. 166 passive air samples, consisting of polyurethane foam (PUF), were collected in 12 African countries between 2010 and 2018. Samples were extracted with methanol and analyzed via high-performance liquid chromatography coupled with tandem mass spectrometry. The detection frequencies of CUPs per site were compared to land use patterns and sampling years, while their similarities were assessed using hierarchical cluster analysis. Overall, 24 CUPs were detected at least once. In 93% of all samples, at least one CUP was detected, while 78% of the samples had mixtures of two or more CUPs (median 3, interquartile range 5). Atrazine and chlorpyrifos were detected in 19 out of 20 sampling sites. Carbaryl, metazachlor, simazine, tebuconazole and terbuthylazine had the highest detection frequencies at sampling sites dominated by croplands. Across all the sampling years, 16 CUPs were present. Seven CUPs were newly detected from 2016 onwards (azinfos-methyl, dimetachlor, chlorsulfuron, chlortoluron, isoproturon, prochloraz and pyrazon), while metamitron was only present before 2012. Sites within a radius of about 200 km showed similarities in detected CUP mixtures across all samples. Our results show the presence of CUP mixtures across multiple agricultural and urban locations in Africa which requires further investigation of related environmental and human health risks.

Endocrine-disrupting chemicals: economic, regulatory, and policy implications

Endocrine-disrupting chemicals (EDCs) substantially cost society as a result of increases in disease and disability but-unlike other toxicant classes such as carcinogens-have yet to be codified into regulations as a hazard category. This Series paper examines economic, regulatory, and policy approaches to limit human EDC exposures and describes potential improvements. In the EU, general principles for EDCs call for minimisation of human exposure, identification as substances of very high concern, and ban on use in pesticides. In the USA, screening and testing programmes are focused on oestrogenic EDCs exclusively, and regulation is strictly risk-based. Minimisation of human exposure is unlikely without a clear overarching definition for EDCs and relevant pre-marketing test requirements. We call for a multifaceted international programme (eg, modelled on the International Agency for Research in Cancer) to address the effects of EDCs on human health-an approach that would proactively identify hazards for subsequent regulation.

Census Demographics and Chlorpyrifos Use in California's Central Valley, 2011-15: A Distributional Environmental Justice Analysis

Chlorpyrifos, an acetylcholinesterase inhibitor (ACI), is one of the most widely used insecticides in the world, and is generally recognized to be a moderate human neurotoxin. This paper reports a distributional environmental justice (dEJ) analysis of chlorpyrifos use in California’s Central Valley, examining the way distributions of environmental risks are associated with race, ethnicity, class, gender, and other systems of structural oppression. Spatial data on chlorpyrifos use were retrieved from California’s Department of Pesticide Registration public pesticide use records for 2011–2015. These data were combined with demographic data for the Central Valley from the American Community Survey (ACS). Spatial regression models were used to estimate effects of demographic covariates on local chlorpyrifos use. A novel bootstrap method was used to account for measurement error in the ACS estimates. This study finds consistent evidence that Hispanic population proportion is associated with increased local chlorpyrifos use. A 10-point increase in Hispanic proportion is associated with an estimated 1.05–1.4-fold increase in local chlorpyrifos use across Census tract models. By contrast, effects of agricultural employment and poverty on local chlorpyrifos use are ambiguous and inconsistent between Census tracts and Census-designated places.

Trends in neurodevelopmental disability burden due to early life chemical exposure in the USA from 2001 to 2016: A population-based disease burden and cost analysis

Endocrine disrupting chemicals are known to cause neurodevelopmental toxicity through direct and indirect pathways. In this study we used data from the National Health and Nutrition Examination Surveys, along with known exposure-disease relationships, to quantify the intellectual disability burden attributable to in utero exposure to polybrominated diphenyl ethers (PBDEs), organophosphates, and methylmercury and early life exposure to lead. We also estimated the cost of the IQ points lost and cases of intellectual disability. PBDE exposure was the greatest contributor to intellectual disability burden, resulting in a total of 162 million IQ points lost and over 738,000 cases of intellectual disability. This was followed by lead, organophosphates, and methylmercury. From 2001 to 2016, IQ loss from PBDEs, methylmercury, and lead have decreased or remained stagnant. Organophosphate exposure measurements were only available up to 2008 but did show an increase in organophosphate-attributable IQ loss. Although most of these trends show benefit for children's neurodevelopmental health, they may also point towards the use of potentially harmful substitutions for chemicals that are being phased out.

Adult exposure to insecticides causes persistent behavioral and neurochemical alterations in zebrafish

Farmers are often chronically exposed to insecticides, which may present health risks including increased risk of neurobehavioral impairment during adulthood and across aging. Experimental animal studies complement epidemiological studies to help determine the cause-and-effect relationship between chronic adult insecticide exposure and behavioral dysfunction. With the zebrafish model, we examined short and long-term neurobehavioral effects of exposure to either an organochlorine insecticide, dichlorodiphenyltrichloroethane (DDT) or an organophosphate insecticide chlorpyrifos (CPF). Adult fish were exposed continuously for either two or 5 weeks (10-30 nM DDT, 0.3-3 μM CPF), with short- and long-term effects assessed at 1-week post-exposure and at 14 months of age respectively. The behavioral test battery included tests of locomotor activity, tap startle, social behavior, anxiety, predator avoidance and learning. Long-term effects on neurochemical indices of cholinergic function were also assessed. Two weeks of DDT exposure had only slight effects on locomotor activity, while a longer five-week exposure led to hypoactivity and increased anxiety-like diving responses and predator avoidance at 1-week post-exposure. When tested at 14 months of age, these fish showed hypoactivity and increased startle responses. Cholinergic function was not found to be significantly altered by DDT. The two-week CPF exposure led to reductions in anxiety-like diving and increases in shoaling responses at the 1-week time point, but these effects did not persist through 14 months of age. Nevertheless, there were persistent decrements in cholinergic presynaptic activity. A five-week CPF exposure led to long-term effects including locomotor hyperactivity and impaired predator avoidance at 14 months of age, although no effects were apparent at the 1-week time point. These studies documented neurobehavioral effects of adult exposure to chronic doses of either organochlorine or organophosphate pesticides that can be characterized in zebrafish. Zebrafish provide a low-cost model that has a variety of advantages for mechanistic studies and may be used to expand our understanding of neurobehavioral toxicity in adulthood, including the potential for such toxicity to influence behavior and development during aging.

Pesticides With Potential Thyroid Hormone-Disrupting Effects: A Review of Recent Data

Plant Protection Products, more commonly referred to as pesticides and biocides, are used to control a wide range of yield-reducing pests including insects, fungi, nematodes, and weeds. Concern has been raised that some pesticides may act as endocrine disrupting chemicals (EDCs) with the potential to interfere with the hormone systems of non-target invertebrates and vertebrates, including humans. EDCs act at low doses and particularly vulnerable periods of exposure include pre- and perinatal development. Of critical concern is the number of pesticides with the potential to interfere with the developing nervous system and brain, notably with thyroid hormone signaling. Across vertebrates, thyroid hormone orchestrates metamorphosis, brain development, and metabolism. Pesticide action on thyroid homeostasis can involve interference with TH production and its control, displacement from distributor proteins and liver metabolism. Here we focused on thyroid endpoints for each of the different classes of pesticides reviewing epidemiological and experimental studies carried out both in in vivo and in vitro. We conclude first, that many pesticides were placed on the market with insufficient testing, other than acute or chronic toxicity, and second, that thyroid-specific endpoints for neurodevelopmental effects and mixture assessment are largely absent from regulatory directives.

Chemicals Denial—A Challenge to Science and Policy

Much research shows that science denial regarding climate change is widespread and problematic for science and scientists, as well as for policy-makers. Climate denial delays goal achievement. As shown in this article, science denial commonly occurs also in the field of chemicals assessment and policy, but the research on the topic is scarce. The peer-reviewed studies that exist mostly concern a limited number of specific cases, such as DDT, CFCs and endocrine disrupting chemicals. The characteristics of ‘chemicals denial’ show similarity with those of climate denial, including reliance on fake experts, cherry-picked facts and attacks on scientists, with a key aspect being the questioning of causal relationships. Considering the gaps between chemicals policy goals and the state of the environment, further scientific exploration in the field is needed. Developing a better coordinated research agenda and a common terminology are therefore warranted strategies. A key concept in such endeavors could be ‘chemicals denial’.

Chlorpyrifos Exposure Induces Parkinsonian Symptoms and Associated Bone Loss in Adult Swiss Albino Mice

Prenatal and early life exposure of chlorpyrifos (CPF), a widely used pesticide, is known to cause neuronal deficits and Parkinson's disease (PD). However, data about the effect of its exposure at adult stages on PD-like symptoms and associated bone loss is scanty. In the present study, we investigated the impact of CPF on the behavioral alterations seen in PD using adult Swiss albino mice. PD is often associated with bone loss. Hence, skeletal changes were also evaluated using micro-computed tomography and histology. MPTP was used as a positive control. Cell culture studies using MC3T3E-1, SHSY5Y, and primary osteoclast cultures were done to understand the cellular mechanism for the behavioral and skeletal changes. Our results showed that CPF treatment leads to PD-like symptoms due to the loss of dopaminergic neurons. Moreover, CPF has a deleterious effect on the trabecular bone through both indirect changes in circulating factors and direct stimulation of multinucleate osteoclast cell formation. The impact on the bone mass was even stronger than MPTP. In conclusion, this is the first report demonstrating that CPF induces parkinsonian features in adult Swiss albino mice and it is accompanied by loss of trabecular bone.

The USA lags behind other agricultural nations in banning harmful pesticides

BACKGROUND

The United States of America (USA), European Union (EU), Brazil and China are four of the largest agricultural producers and users of agricultural pesticides in the world. Comparing the inclination and ability of different regulatory agencies to ban or eliminate pesticides that have the most potential for harm to humans and the environment can provide a glimpse into the effectiveness of each nation's pesticide regulatory laws and oversight.

METHODS

The approval status of more than 500 agricultural pesticides was identified in the USA, EU, Brazil and China and compared between nations. The amount of pesticides that were used in the USA and banned in these other nations was compiled and linear regression was used to identify trends in use.

RESULTS

There are 72, 17, and 11 pesticides approved for outdoor agricultural applications in the USA that are banned or in the process of complete phase out in the EU, Brazil, and China, respectively. Of the pesticides used in USA agriculture in 2016, 322 million pounds were of pesticides banned in the EU, 26 million pounds were of pesticides banned in Brazil and 40 million pounds were of pesticides banned in China. Pesticides banned in the EU account for more than a quarter of all agricultural pesticide use in the USA. The majority of pesticides banned in at least two of these three nations have not appreciably decreased in the USA over the last 25 years and almost all have stayed constant or increased over the last 10 years.

CONCLUSIONS

Many pesticides still widely used in the USA, at the level of tens to hundreds of millions of pounds annually, have been banned or are being phased out in the EU, China and Brazil. Of the pesticides banned in at least two of these nations, many have been implicated in acute pesticide poisonings in the USA and some are further restricted by individual states. The United States Environmental Protection Agency (US EPA) has all but abandoned its use of non-voluntary cancellations in recent years, making pesticide cancellation in the USA largely an exercise that requires consent by the regulated industry.

Disruption in Thyroid Signaling Pathway: A Mechanism for the Effect of Endocrine-Disrupting Chemicals on Child Neurodevelopment

Thyroid hormones are crucial in normal brain development. Transient and mild thyroid hormone insufficiency in pregnancy is also associated with impaired neurodevelopment in the offspring (e.g., 3-4 IQ score loss in association with maternal free thyroxine in the lowest fifth percentile). While inadequate iodine intake remains the most common underlying cause of mild thyroid hormone insufficiency in vulnerable populations including pregnant women, other factors such as exposure to environmental contaminants have recently attracted increasing attention, in particular in interaction with iodine deficiency. Endocrine-disrupting chemicals (EDCs) are natural and synthetic substances with ubiquitous exposure in children and adults including pregnant women. EDCs interfere, temporarily or permanently, with hormonal signaling pathways in the endocrine system by binding to hormone receptors and modifying gene expression. Other mechanisms involve alterations in production, metabolism, and transfer of hormones. Experimental studies have shown that exposures to EDCs affect various brain processes such as neurogenesis, neural differentiation and migration, as well as neural connectivity. Neuroimaging studies confirm brain morphological abnormalities (e.g., cortical thinning) consistent with neurodevelopmental impairments as a result of EDC exposures at standard use levels. In this review, we provide an overview of present findings from toxicological and human studies on the anti-thyroid effect of EDCs with a specific attention to fetal and early childhood exposure. This brief overview highlights the need for additional multidisciplinary studies with a focus on thyroid disruption as an underlying mechanism for developmental neurotoxicity of EDC, which can provide insight into modifiable risk factors of developmental delays in children.

Thyroid-disrupting chemicals and brain development: an update

This review covers recent findings on the main categories of thyroid hormone-disrupting chemicals and their effects on brain development. We draw mostly on epidemiological and experimental data published in the last decade. For each chemical class considered, we deal with not only the thyroid hormone-disrupting effects but also briefly mention the main mechanisms by which the same chemicals could modify estrogen and/or androgen signalling, thereby exacerbating adverse effects on endocrine-dependent developmental programmes. Further, we emphasize recent data showing how maternal thyroid hormone signalling during early pregnancy affects not only offspring IQ, but also neurodevelopmental disease risk. These recent findings add to established knowledge on the crucial importance of iodine and thyroid hormone for optimal brain development. We propose that prenatal exposure to mixtures of thyroid hormone-disrupting chemicals provides a plausible biological mechanism contributing to current increases in the incidence of neurodevelopmental disease and IQ loss.