Heemstra, 2020
Heemstra, J. M.; “A Scientist’s Guide to Social Media;” ACS Central Science, 2020, 6(1), 1-5; DOI: 10.1021/acscentsci.9b01273.
ABSTRACT:
Not Available
Bibliography Tag: full text available
Kezic and Nielsen, 2009
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.
ABSTRACT:
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
Gorga et al., 2021
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.
ABSTRACT:
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
Mahler et al., 2021
Mahler, B. J., Nowell, L. H., Sandstrom, M. W., Bradley, P. M., Romanok, K. M., Konrad, C. P., & Van Metre, P. C.; “Inclusion of Pesticide Transformation Products Is Key to Estimating Pesticide Exposures and Effects in Small U.S. Streams;” Environmental Science & Technology, 2021; DOI: 10.1021/acs.est.0c06625.
ABSTRACT:
Improved analytical methods can quantify hundreds of pesticide transformation products (TPs), but understanding of TP occurrence and potential toxicity in aquatic ecosystems remains limited. We quantified 108 parent pesticides and 116 TPs in more than 3700 samples from 442 small streams in mostly urban basins across five major regions of the United States. TPs were detected nearly as frequently as parents (90 and 95% of streams, respectively); 102 TPs were detected at least once and 28 were detected in >20% samples in at least one region-TPs of 9 herbicides, 2 fungicides (chlorothalonil and thiophanate-methyl), and 1 insecticide (fipronil) were the most frequently detected. TPs occurred commonly during baseflow conditions, indicating chronic environmental TP exposures to aquatic organisms and the likely importance of groundwater as a TP source. Hazard quotients based on acute aquatic-life benchmarks for invertebrates and nonvascular plants and vertebrate-centric molecular endpoints (sublethal effects) quantify the range of the potential contribution of TPs to environmental risk and highlight several TP exposure-response data gaps. A precautionary approach using equimolar substitution of parent benchmarks or endpoints for missing TP benchmarks indicates that potential aquatic effects of pesticide TPs could be underestimated by an order of magnitude or more. FULL TEXT
Tang et al., 2021
Tang, Fiona H. M., Lenzen, Manfred, McBratney, Alexander, & Maggi, Federico; “Risk of pesticide pollution at the global scale;” Nature Geoscience, 2021; DOI: 10.1038/s41561-021-00712-5.
ABSTRACT:
Pesticides are widely used to protect food production and meet global food demand but are also ubiquitous environmental pollutants, causing adverse effects on water quality, biodiversity and human health. Here we use a global database of pesticide applications and a spatially explicit environmental model to estimate the world geography of environmental pollution risk caused by 92 active ingredients in 168 countries. We considered a region to be at risk of pollution if pesticide residues in the environment exceeded the no-effect concentrations, and to be at high risk if residues exceeded this by three orders of magnitude. We find that 64% of global agricultural land (approximately 24.5 million km2) is at risk of pesticide pollution by more than one active ingredient, and 31% is at high risk. Among the high-risk areas, about 34% are in high-biodiversity regions, 5% in water-scarce areas and 19% in low- and lower-middle-income nations. We identify watersheds in South Africa, China, India, Australia and Argentina as high-concern regions because they have high pesticide pollution risk, bear high biodiversity and suffer from water scarcity. Our study expands earlier pesticide risk assessments as it accounts for multiple active ingredients and integrates risks in different environmental compartments at a global scale. FULL TEXT
Geer et al., 2004
Geer, L. A., Cardello, N., Dellarco, M. J., Leighton, T. J., Zendzian, R. P., Roberts, J. D., & Buckley, T. J.; “Comparative analysis of passive dosimetry and biomonitoring for assessing chlorpyrifos exposure in pesticide workers;” Annals of Occupational Hygeine, 2004, 48(8), 683-695; DOI: 10.1093/annhyg/meh056.
ABSTRACT:
Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), the US Environmental Protection Agency (EPA) has the authority to regulate the use of pesticides to prevent unreasonable adverse human health effects associated with pesticide exposure. Accordingly, the EPA requires pesticide registrants to perform studies evaluating the potential for pesticide handler exposure. Data from five such studies that included exposure measurements based on both external measurements and biological monitoring were used to examine methods of assessment, routes and determinants of exposure and dose to the pesticide chlorpyrifos. Eighty workers across four job classes were included: mixer/loaders (M/L, n = 24), mixer/loader/applicators (M/L/A, n = 37), applicators (A, n = 9) and re-entry scouts (RS, n = 10). Results showed that doses were highly variable and differed by job class (P < 0.05) with median total (inhalation and dermal combined) exposure-derived absorbed doses (EDADtot) of 129, 88, 85 and 45 microg/application for A, M/L/A, M/L and RS, respectively. Doses derived from the measurement of 3,5,6-trichloro- 2-pyridinol (3,5,6-TCP) in urine were similar in magnitude but differed in rank with median values of 275, 189, 122 and 97 microg/application for A, M/L, RS, and M/L/A, respectively. The relative contribution of dermal to inhalation exposure was examined by their ratio. The median ratios of exposure-derived absorbed dermal dose (EDADderm) (assuming 3% absorption) to exposure-derived absorbed inhalation dose (EDADinh) (assuming 100% absorption) across job classes were 1.7, 1.5, 0.44 and 0.18 for RS, M/L, A and M/L/A, respectively, with an overall median of 0.6. For 34 of 77 workers (44%), this ratio exceeded 1.0, indicating the significance of the dermal exposure pathway. Different dermal absorption factor (DAF) assumptions were examined by comparing EDADtot to the biomarker-derived absorbed dose (BDAD) as a ratio where EDADtot was calculated assuming a DAF of 1, 3 and 10%. Median ratios of 0.45, 0.71 and 1.28, respectively, were determined suggesting the DAF is within the range of 3-10%. A simple linear regression of urinary 3,5,6-TCP against EDADtot indicates a positive association explaining 29% of the variability in the 3,5,6-TCP derived estimate of dose. A multiple linear regression model including the variables EDADderm, EDADinh and application type explained 46% of the variability (R2 = 0.46) in the urinary dose estimate. EDADderm was marginally significant (P = 0.066) while EDADinh was not (P = 0.57). The EDADderm regression coefficient (0.0007) exceeded the coefficient for EDADinh (0.00002) by a factor of 35. This study demonstrates the value of the pesticide registrant database for the purpose of evaluating pesticide worker exposure. It highlights the significance of the dermal exposure pathway, and identifies the need for methods and research to close the gap between external and internal exposure measures. FULL TEXT
Meuling et al., 2005
Meuling, W. J., Ravensberg, L. C., Roza, L., & van Hemmen, J. J.; “Dermal absorption of chlorpyrifos in human volunteers;” International Archives of Occupational and Environmental Health, 2005, 78(1), 44-50; DOI: 10.1007/s00420-004-0558-6.
ABSTRACT:
OBJECTIVE: The methods and results are described of a study on the dermal absorption of chlorpyrifos (CPF) in humans established via urinary excretion of the metabolite 3,5,6-trichloro-2-pyridinol (TCP).
METHODS: Two dermal, single, doses of CPF were applied in two study groups (A and B) each comprising three apparently healthy male volunteers who gave their written informed consent. The clinical part of the study was conducted in compliance with the ICH Guideline and the EC principles of good clinical practice (GCP). An approximately 0.5 ml dilution of CPF in ethanol was applied to an area of approximately 100 cm(2) of the volar aspect of the forearm, resulting in doses of either 5 mg (A) or 15 mg (B) of CPF per study subject. Duration of dermal exposure was 4 h, after which the non-absorbed fraction was washed off. The following samples were collected at pre-determined intervals for the determination of either CPF or its metabolite TCP: dosing solutions, wash-off fractions and urine samples collected up to 120 h after dosing.
RESULTS: A relatively large fraction of CPF (42%-67% of the applied dose) was washed off from the exposed skin area. Application of either 5 mg (A) or 15 mg CPF (B) resulted in the total urinary excretion of 131.8 microg (A) or 115.6 microg (B) of TCP 120 h after dosing. This indicated that 4.3% of the applied dose has been absorbed (A), while in group (B) no significant increase in urinary TCP (115.6 microg) was established. The latter indicates that an increase in the dermal dose at a fixed area does not increase absorption, which suggests that the percutaneous penetration rate was constant. Further, it was observed that the clearance of CPF by the body was not completed within 120 h, suggesting that CPF or TCP was retained by the skin and/or accumulated in the body. A mean elimination half-life of 41 h was established.
CONCLUSION: The results show that daily occupational exposure to CPF may result in accumulation of CPF and/or its metabolites, possibly resulting in adverse effects. FULL TEXT
O’Leary et al., 1970
O’Leary, James A., Davies, John E., Edmundson, Walter F., & Reich, George A.; “Transplacental passage of pesticides;” American Journal of Obstetrics and Gynecology, 1970, 107(1), 65-68; DOI: 10.1016/s0002-9378(16)33891-1.
ABSTRACT:
The levels of chlorinated hydrocarbon pesticides in blood and tissues of pregnant women have not been adequately studied, although it has been stated that DDT or its metabolites may be detected in most infants born in America today. The occurrence of these chemicals in neonates has been documented by Denes. For the most part, the biological effects of acute exposure to many pesticides are well known, although this is not true regarding chronic and subacute exposure. In addition, the chlorinated hydrocarbons have been shown to be powerful stimulators of the hepatic microsomal enzyme system:; and these effects remain to be determined. For this reason increased emphasis in this research area is advisable.
The application of gas chromatography and development of the electron capture detector have made possible the determination of levels of many pesticides in every tissue, thus opening new avenues of investigation. The data in this report are presented as an effort toward the clearer understanding of the possible effects of concentrations of pesticides in blood and other tissues during pregnancy, and represent conclusive evidence of the quantitative transfer of DDT and its metabolites to the fetus. The variables of maternal race and fetal maturity are considered. FULL TEXT
Rueda-Ruzafa et al., 2019
Rueda-Ruzafa, L., Cruz, F., Roman, P., & Cardona, D.; “Gut microbiota and neurological effects of glyphosate;” NeuroToxicology, 2019, 75, 1-8; DOI: 10.1016/j.neuro.2019.08.006.
ABSTRACT:
There are currently various concerns regarding certain environmental toxins and the possible impact they can have on developmental diseases. Glyphosate (Gly) is the most utilised herbicide in agriculture, although its widespread use is generating controversy in the scientific world because of its probable carcinogenic effect on human cells. Gly performs as an inhibitor of 5-enolpyruvylshikimate-3-phospate synthase (EPSP synthase), not only in plants, but also in bacteria. An inhibiting effect on EPSP synthase from intestinal microbiota has been reported, affecting mainly beneficial bacteria. To the contrary, Clostridium spp. and Salmonella strains are shown to be resistant to Gly. Consequently, researchers have suggested that Gly can cause dysbiosis, a phenomenon which is characterised by an imbalance between beneficial and pathogenic microorganisms. The overgrowth of bacteria such as clostridia generates high levels of noxious metabolites in the brain, which can contribute to the development of neurological deviations. This work reviews the impact of Gly-induced intestinal dysbiosis on the central nervous system, focusing on emotional, neurological and neurodegenerative disorders. A wide variety of factors were investigated in relation to brain-related changes, including highlighting genetic abnormalities, pregnancy-associated problems, diet, infections, vaccines and heavy metals. However, more studies are required to determine the implication of the most internationally used herbicide, Gly, in behavioural disorders. FULL TEXT
Macfarlane et al., 2013
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.
ABSTRACT:
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.