Riter, L. S., Sall, E. D., Pai, N., Beachum, C. E., & Orr, T. B.; “Quantifying Dicamba Volatility under Field Conditions: Part I, Methodology;” Journal of Agricultural and Food Chemistry, 2020, 68(8), 2277-2285; DOI: 10.1021/acs.jafc.9b06451.
Quantitative assessment of the volatility of field applied herbicides requires orchestrated sampling logistics, robust analytical methods, and sophisticated modeling techniques. This manuscript describes a comprehensive system developed to measure dicamba volatility in an agricultural setting. Details about study design, sample collection, analytical chemistry, and flux modeling are described. A key component of the system is the interlaboratory validation of an analytical method for trace level detection (limit of quantitation of 1.0 ng/PUF) of dicamba in polyurethane foam (PUF) air samplers. Validation of field sampling and flux methodologies was conducted in a field trial that demonstrated agreement between predicted and directly measured dicamba air concentrations at a series of off-target locations. This validated system was applied to a field case study on two plots to demonstrate the utility of these methods under typical agricultural conditions. This case study resulted in a time-varying volatile flux profile, which showed that less than 0.2 +/- 0.05% of the applied dicamba was volatilized over the 3-day sampling period. FULL TEXT
Macfarlane, E., Carey, R., Keegel, T., El-Zaemay, S., & Fritschi, L.; “Dermal exposure associated with occupational end use of pesticides and the role of protective measures;” Safety and Health at Work, 2013, 4(3), 136-141; DOI: 10.1016/j.shaw.2013.07.004.
BACKGROUND: Occupational end users of pesticides may experience bodily absorption of the pesticide products they use, risking possible health effects. The purpose of this paper is to provide a guide for researchers, practitioners, and policy makers working in the field of agricultural health or other areas where occupational end use of pesticides and exposure issues are of interest.
METHODS: This paper characterizes the health effects of pesticide exposure, jobs associated with pesticide use, pesticide-related tasks, absorption of pesticides through the skin, and the use of personal protective equipment (PPE) for reducing exposure.
CONCLUSIONS: Although international and national efforts to reduce pesticide exposure through regulatory means should continue, it is difficult in the agricultural sector to implement engineering or system controls. It is clear that use of PPE does reduce dermal pesticide exposure but compliance among the majority of occupationally exposed pesticide end users appears to be poor. More research is needed on higher-order controls to reduce pesticide exposure and to understand the reasons for poor compliance with PPE and identify effective training methods.
Schlappi, D., Kettler, N., Straub, L., Glauser, G., & Neumann, P.; “Long-term effects of neonicotinoid insecticides on ants;” Communications Biology, 2020, 3(1), 335; DOI: 10.1038/s42003-020-1066-2.
The widespread prophylactic usage of neonicotinoid insecticides has a clear impact on non-target organisms. However, the possible effects of long-term exposure on soil-dwelling organisms are still poorly understood especially for social insects with long-living queens. Here, we show that effects of chronic exposure to the neonicotinoid thiamethoxam on black garden ant colonies, Lasius niger, become visible before the second overwintering. Queens and workers differed in the residue-ratio of thiamethoxam to its metabolite clothianidin, suggesting that queens may have a superior detoxification system. Even though thiamethoxam did not affect queen mortality, neonicotinoid-exposed colonies showed a reduced number of workers and larvae indicating a trade-off between detoxification and fertility. Since colony size is a key for fitness, our data suggest long-term impacts of neonicotinoids on these organisms. This should be accounted for in future environmental and ecological risk assessments of neonicotinoid applications to prevent irreparable damages to ecosystems. FULL TEXT
Moore, C. A., Wilkinson, S. C., Blain, P. G., Dunn, M., Aust, G. A., & Williams, F. M.; “Percutaneous absorption and distribution of organophosphates (chlorpyrifos and dichlorvos) following dermal exposure and decontamination scenarios using in vitro human skin model;” Toxicology Letters, 2014, 229(1), 66-72; DOI: 10.1016/j.toxlet.2014.06.008.
To date, there has been little research investigating low-level human exposure to chemicals, and so the aim of this study was to examine the percutaneous penetration of organophosphates (dichlorvos and chlorpyrifos) using low-level exposure scenarios in vitro. Dermal absorption of chlorpyrifos applied in different vehicles was measured at 0, 4, 8 and 24 h, after dose application for 4 and 24 h exposure (finite dose, 500 ng/cm(2)) in isopropanol (IPA), isopropyl myristate (IPM) and propylene glycol (PG). Dichlorvos was applied to the skin for 24 h (infinite dose, 1 mg/cm(2) and 10 mg/cm(2); finite dose, 5 mug/cm(2)) using the same vehicles. Human skin was mounted in flow through diffusion cells with minimum essential medium eagle pH 7.4 (supplemented with 2% BSA) as receptor fluid. Following exposure, the skin surface dose was removed by tissue swabbing, the stratum corneum removed by sequential tape stripping, and the skin digested prior to scintillation counting (chlorpyrifos), or GC/MS analysis (dichlorvos). The dermal absorption of chlorpyrifos was the greatest following application in PG (19.5% of dose), when compared with absorption from the IPA and IPM vehicles (10.3% and 1.9% absorbed respectively). However, dichlorvos showed greater dermal absorption than chlorpyrifos from all vehicles used, with greatest absorption from the IPA vehicle (38.6% absorbed). Although dichlorvos exhibited a short lag time (0.6 h from IPA and IP vehicles, and 0.4 h from PG), chlorpyrifos displayed greater propensity to accumulate in the stratum corneum and epidermis/dermis. These results demonstrate that prompt skin surface decontamination would be required for both dichlorvos and chlorpyrifos (and chemicals with similar properties) in the event of skin contact. The magnitude of the skin reservoir formed with chlorpyrifos was time dependent, therefore, prompt decontamination of this and similar chemicals would be required to reduce delayed systemic absorption.
Pisa, L. W., Amaral-Rogers, V., Belzunces, L. P., Bonmatin, J. M., Downs, C. A., Goulson, D., Kreutzweiser, D. P., Krupke, C., Liess, M., McField, M., Morrissey, C. A., Noome, D. A., Settele, J., Simon-Delso, N., Stark, J. D., Van der Sluijs, J. P., Van Dyck, H., & Wiemers, M.; “Effects of neonicotinoids and fipronil on non-target invertebrates;” Environmental Science and Pollution Research International, 2015, 22(1), 68-102; DOI: 10.1007/s11356-014-3471-x.
We assessed the state of knowledge regarding the effects of large-scale pollution with neonicotinoid insecticides and fipronil on non-target invertebrate species of terrestrial, freshwater and marine environments. A large section of the assessment is dedicated to the state of knowledge on sublethal effects on honeybees (Apis mellifera) because this important pollinator is the most studied non-target invertebrate species. Lepidoptera (butterflies and moths), Lumbricidae (earthworms), Apoidae sensu lato (bumblebees, solitary bees) and the section “other invertebrates” review available studies on the other terrestrial species. The sections on freshwater and marine species are rather short as little is known so far about the impact of neonicotinoid insecticides and fipronil on the diverse invertebrate fauna of these widely exposed habitats. For terrestrial and aquatic invertebrate species, the known effects of neonicotinoid pesticides and fipronil are described ranging from organismal toxicology and behavioural effects to population-level effects. For earthworms, freshwater and marine species, the relation of findings to regulatory risk assessment is described. Neonicotinoid insecticides exhibit very high toxicity to a wide range of invertebrates, particularly insects, and field-realistic exposure is likely to result in both lethal and a broad range of important sublethal impacts. There is a major knowledge gap regarding impacts on the grand majority of invertebrates, many of which perform essential roles enabling healthy ecosystem functioning. The data on the few non-target species on which field tests have been performed are limited by major flaws in the outdated test protocols. Despite large knowledge gaps and uncertainties, enough knowledge exists to conclude that existing levels of pollution with neonicotinoids and fipronil resulting from presently authorized uses frequently exceed the lowest observed adverse effect concentrations and are thus likely to have large-scale and wide ranging negative biological and ecological impacts on a wide range of non-target invertebrates in terrestrial, aquatic, marine and benthic habitats. FULL TEXT
Levine, H., Jorgensen, N., Martino-Andrade, A., Mendiola, J., Weksler-Derri, D., Mindlis, I., Pinotti, R., & Swan, S. H.; “Temporal trends in sperm count: a systematic review and meta-regression analysis;” Human Reproduction Update, 2017, 23(6), 646-659; DOI: 10.1093/humupd/dmx022.
BACKGROUND: Reported declines in sperm counts remain controversial today and recent trends are unknown. A definitive meta-analysis is critical given the predictive value of sperm count for fertility, morbidity and mortality.
OBJECTIVE AND RATIONALE: To provide a systematic review and meta-regression analysis of recent trends in sperm counts as measured by sperm concentration (SC) and total sperm count (TSC), and their modification by fertility and geographic group.
SEARCH METHODS: PubMed/MEDLINE and EMBASE were searched for English language studies of human SC published in 1981-2013. Following a predefined protocol 7518 abstracts were screened and 2510 full articles reporting primary data on SC were reviewed. A total of 244 estimates of SC and TSC from 185 studies of 42 935 men who provided semen samples in 1973-2011 were extracted for meta-regression analysis, as well as information on years of sample collection and covariates [fertility group (‘Unselected by fertility’ versus ‘Fertile’), geographic group (‘Western’, including North America, Europe Australia and New Zealand versus ‘Other’, including South America, Asia and Africa), age, ejaculation abstinence time, semen collection method, method of measuring SC and semen volume, exclusion criteria and indicators of completeness of covariate data]. The slopes of SC and TSC were estimated as functions of sample collection year using both simple linear regression and weighted meta-regression models and the latter were adjusted for pre-determined covariates and modification by fertility and geographic group. Assumptions were examined using multiple sensitivity analyses and nonlinear models.
OUTCOMES: SC declined significantly between 1973 and 2011 (slope in unadjusted simple regression models -0.70 million/ml/year; 95% CI: -0.72 to -0.69; P < 0.001; slope in adjusted meta-regression models = -0.64; -1.06 to -0.22; P = 0.003). The slopes in the meta-regression model were modified by fertility (P for interaction = 0.064) and geographic group (P for interaction = 0.027). There was a significant decline in SC between 1973 and 2011 among Unselected Western (-1.38; -2.02 to -0.74; P < 0.001) and among Fertile Western (-0.68; -1.31 to -0.05; P = 0.033), while no significant trends were seen among Unselected Other and Fertile Other. Among Unselected Western studies, the mean SC declined, on average, 1.4% per year with an overall decline of 52.4% between 1973 and 2011. Trends for TSC and SC were similar, with a steep decline among Unselected Western (-5.33 million/year, -7.56 to -3.11; P < 0.001), corresponding to an average decline in mean TSC of 1.6% per year and overall decline of 59.3%. Results changed minimally in multiple sensitivity analyses, and there was no statistical support for the use of a nonlinear model. In a model restricted to data post-1995, the slope both for SC and TSC among Unselected Western was similar to that for the entire period (-2.06 million/ml, -3.38 to -0.74; P = 0.004 and -8.12 million, -13.73 to -2.51, P = 0.006, respectively).
WIDER IMPLICATIONS: This comprehensive meta-regression analysis reports a significant decline in sperm counts (as measured by SC and TSC) between 1973 and 2011, driven by a 50-60% decline among men unselected by fertility from North America, Europe, Australia and New Zealand. Because of the significant public health implications of these results, research on the causes of this continuing decline is urgently needed.
Heemstra, J. M.; “A Scientist’s Guide to Social Media;” ACS Central Science, 2020, 6(1), 1-5; DOI: 10.1021/acscentsci.9b01273.
Kezic, S., & Nielsen, J. B.; “Absorption of chemicals through compromised skin;” International Archives of Occupational and Environmental Health, 2009, 82(6), 677-688; DOI: 10.1007/s00420-009-0405-x.
Skin is an important route of entry for many chemicals in the work place. To assess systemic uptake of a chemical in contact with the skin, quantitative information on dermal absorption rates of chemicals is needed. Absorption rates are mainly obtained from studies performed with intact, healthy skin. At the work place, however, a compromised skin barrier, although not necessarily visible is common, e.g. due to physical and chemical damage. As reviewed in this article, there are several lines of evidence that reduced integrity of the skin barrier may increase dermal absorption of chemicals in the occupational setting. An impaired skin barrier might lead not only to enhanced absorption of a specific chemical, but also to entrance of larger molecules such as proteins and nanoparticles which normally are not able to penetrate intact skin. In addition to environmental influences, there is increasing evidence that some individuals have an intrinsically affected skin barrier which will facilitate entrance of chemicals into and through the skin making these persons more susceptible for local as well for systemic toxicity. This review addresses mechanisms of barrier alteration caused by the most common skin-damaging factors in the occupational settings and the consequences for dermal absorption of chemicals. Furthermore, this review emphasizes the importance of maintained barrier properties of the skin. FULL TEXT
Tang, J., Wang, W., Jiang, Y., & Chu, W.; “Diazinon exposure produces histological damage, oxidative stress, immune disorders and gut microbiota dysbiosis in crucian carp (Carassius auratus gibelio);” Environmental Pollution, 2021, 269, 116129; DOI: 10.1016/j.envpol.2020.116129.
Diazinon is a common organophosphate pesticide widely used to control parasitic infections in agriculture. Excessive use of diazinon can have adverse effects on the environment and aquatic animal health. In the present study, the toxic effects of diazinon on the histology, antioxidant, innate immune and intestinal microbiota community composition of crucian carp (Carassius auratus gibelio) were investigated. The results showed that diazinon at the tested concentration (300 mug/L) induced gill and liver histopathological damages. Hepatic total superoxide dismutase (T-SOD), catalase (CAT), and glutathione S-transferase (GST) activities significantly decreased (P < 0.05) by 32.47%, 65.33% and 37.34%, respectively. However, the liver tissue malondialdehyde (MDA) content significantly (P < 0.05) increased by 138.83%. The 300 mug/L diazinon significantly (P < 0.05) downregulated the gene expression of TLR4, MyD88, NF-kB p100 and IL-8 but had no significant effect TNF-alpha (P = 0.8239). In addition, the results demonstrated that diazinon exposure could affect the intestinal microbiota composition and diversity. Taken together, the results of this study indicated that diazinon exposure can cause damage to crucian carp, induce histopathological damage in gill and liver tissues, oxidative stress in the liver, and innate immune disorders and alter intestinal microbiota composition and diversity.
Gorga, A., Rindone, G. M., Centola, C. L., Sobarzo, C. M., Pellizzari, E. H., Camberos, M. D. C., Marin-Briggiler, C. I., Cohen, D. J., Riera, M. F., Galardo, M. N., & Meroni, S. B.; “Low Doses of Glyphosate/Roundup Alter Blood-Testis Barrier Integrity in Juvenile Rats;” Frontiers in Endocrinology, 2021, 12, 615678; DOI: 10.3389/fendo.2021.615678.
It has been postulated that glyphosate (G) or its commercial formulation Roundup (R) might lead to male fertility impairment. In this study, we investigated the possible effects of G or R treatment of juvenile male rats on blood-testis barrier function and on adult male sperm production. Pups were randomly assigned to the following groups: control group (C), receiving water; G2 and G50 groups, receiving 2 and 50 mg/kg/day G respectively; and R2 and R50 groups receiving 2 and 50 mg/kg/day R respectively. Treatments were performed orally from postnatal day (PND) 14 to 30, period of life that is essential to complete a functional blood-testis barrier. Evaluation was done on PND 31. No differences in body and testis weight were observed between groups. Testis histological analysis showed disorganized seminiferous epithelium, with apparent low cellular adhesion in treated animals. Blood-testis barrier permeability to a biotin tracer was examined. A significant increase in permeable tubules was observed in treated groups. To evaluate possible mechanisms that could explain the effects on blood-testis barrier permeability, intratesticular testosterone levels, androgen receptor expression, thiobarbituric acid reactive substances (TBARS) and the expression of intercellular junction proteins (claudin11, occludin, ZO-1, connexin43, 46, and 50 which are components of the blood-testis barrier) were examined. No modifications in the above-mentioned parameters were detected. To evaluate whether juvenile exposure to G and R could have consequences during adulthood, a set of animals of the R50 group was allowed to grow up until PND 90. Histological analysis showed that control and R50 groups had normal cellular associations and complete spermatogenesis. Also, blood-testis barrier function was recovered and testicular weight, daily sperm production, and epididymal sperm motility and morphology did not seem to be modified by juvenile treatment. In conclusion, the results presented herein show that continuous exposure to low doses of G or R alters blood-testis barrier permeability in juvenile rats. However, considering that adult animals treated during the juvenile stage showed no differences in daily sperm production compared with control animals, it is feasible to think that blood-testis barrier impairment is a reversible phenomenon. More studies are needed to determine possible damage in the reproductive function of human juvenile populations exposed to low doses of G or R. FULL TEXT