Profiles of neonicotinoid insecticides and their metabolites in paired saliva and periodontal blood samples in human from South China: Association with oxidative stress markers.

Neonicotinoid insecticides (NEOs) are widely used around the world. The distribution of NEOs in paired saliva and periodontal blood samples was not previously documented in China. In this study, the concentrations of six NEOs and three corresponding metabolites were measured in 188 paired saliva and periodontal blood samples collected from South China. NEOs and their metabolites were frequently detected (68-94%) in paired saliva and periodontal blood, with median levels of 0.01-0.99 ng/mL. 1-Methyl-3-(tetrahydro-3-furylmethyl) urea was the most predominant NEO in paired saliva (39%) and periodontal blood (42%). Gender-related differences in NEOs and their metabolite concentrations were found: males showed lower levels than females. We calculated the concentration ratios between saliva and periodontal blood (S/PB ratios), and found that the median S/PB ratios of NEO and their metabolites were higher than 1, indicating that NEOs and their metabolites were easily excreted via saliva. 8-Hydroxy-2'-deoxyguanosine (8-OHdG) was measured in paired saliva and periodontal blood as a marker of oxidative stress. 8-OHdG concentrations in saliva and periodontal blood were significantly and positively correlated (p < 0.05) with the concentrations of most NEOs and their metabolites in saliva and periodontal blood samples. These findings indicated that exposure to NEOs and their metabolites is associated with oxidative stress. This study is the first to report NEOs and their metabolites in paired saliva and periodontal blood samples collected from South China.

Sex and adrenal hormones in association with insecticide biomarkers among adolescents living in ecuadorian agricultural communities.

BACKGROUND: Organophosphate, pyrethroid, and neonicotinoid insecticides have resulted in adrenal and gonadal hormone disruption in animal and in vitro studies; limited epidemiologic evidence exists in humans. We assessed relationships of urinary insecticide metabolite concentrations with adrenal and gonadal hormones in adolescents living in Ecuadorean agricultural communities. METHODS: In 2016, we examined 522 Ecuadorian adolescents (11-17y, 50.7% female, 22% Indigenous; ESPINA study). We measured urinary insecticide metabolites, blood acetylcholinesterase activity (AChE), and salivary testosterone, dehydroepiandrosterone (DHEA), 17ß-estradiol, and cortisol. We used general linear models to assess linear (ß = % hormone difference per 50% increase of metabolite concentration) and curvilinear relationships (ß2 = hormone difference per unit increase in squared ln-metabolite) between ln-metabolite or AChE and ln-hormone concentrations, stratified by sex, adjusting for anthropometric, demographic, and awakening response variables. Bayesian Kernel Machine Regression was used to assess non-linear associations and interactions. RESULTS: The organophosphate metabolite malathion dicarboxylic acid (MDA) had positive associations with testosterone (ßboys = 5.88% [1.21%, 10.78%], ßgirls = 4.10% [-0.02%, 8.39%]), and cortisol (ßboys = 6.06 [-0.23%, 12.75%]. Para-nitrophenol (organophosphate) had negatively-trending curvilinear associations, with testosterone (ß2boys = -0.17 (-0.33, -0.003), p = 0.04) and DHEA (ß2boys = -0.49 (-0.80, -0.19), p = 0.001) in boys. The neonicotinoid summary score (ßboys = 5.60% [0.14%, 11.36%]) and the neonicotinoid acetamiprid-N-desmethyl (ßboys = 3.90% [1.28%, 6.58%]) were positively associated with 17ß-estradiol, measured in boys only. No associations between the pyrethroid 3-phenoxybenzoic acid and hormones were observed. In girls, bivariate response associations identified interactions of MDA, Para-nitrophenol, and 3,5,6-trichloro-2-pyridinol (organophosphates) with testosterone and DHEA concentrations. In boys, we observed an interaction of MDA and Para-nitrophenol with DHEA. No associations were identified for AChE. CONCLUSIONS: We observed evidence of endocrine disruption for specific organophosphate and neonicotinoid metabolite exposures in adolescents. Urinary organophosphate metabolites were associated with testosterone and DHEA concentrations, with stronger associations in boys than girls. Urinary neonicotinoids were positively associated with 17ß-estradiol. Longitudinal repeat-measures analyses would be beneficial for causal inference.

The assessment of occupational exposure to diazinon in Nicaraguan plantation workers using saliva biomonitoring.

A cross-sectional study with repeated sample collection in multiple days was conducted to assess diazinon exposures. Saliva and limited blood samples were collected from 10 banana plantation workers involved with diazinon application and their children aged 2-12 years living in Chinandega, Nicaragua. Diazinon concentration-time profiles in saliva varied between two plantations, which reflects the differences of work practices in each plantation. Salivary concentrations of diazinon measured in Plantation 1 applicators continued to increase 2 days after self-reported diazinon application, suggesting an ongoing exposure among these workers. However, salivary diazinon concentrations measured in Plantation 2 applicators were peaked 12 h prior to the first application, and then decreased 36 h post the first application. Diazinon concentrations in saliva were significantly correlated with the time-matched plasma samples collected from the same workers, which is in agreement with the previous published data from animal models. Children's exposure to diazinon through take-home pathway does not exist, as evident by the majority of nondetected saliva samples, and this finding was confirmed by the results from the urine samples. Severe dehydration was observed in many plantation workers and their children, resulting in the loss of some saliva samples, which no doubt have impaired the overall quality of the study results. Regardless, this article has demonstrated that saliva can be used to assess exposures to diazinon in pesticide applicators and children.

Measurement of organochlorine levels in postprandial serum or in blood collected in serum separator tubes.

Whether organochlorine blood levels in fasting and postprandial specimens provide equivalent measures of exposure and the extent to which collecting blood in tubes containing material to separate serum and blood cells corrupts the specimen are unclear. In this paper, we present data from two studies that address both of these issues. In the first study, 27 women provided fasting blood in plain, silicone-coated Vacutainer tubes (red-topped) and in similar tubes containing serum separator gel (SSTs), as well as a postprandial specimen in a red-topped tube. The specimens collected in SSTs were left to stand overnight, with the gel in contact with the sample. In the second study, the blood of 12 industrial incinerator workers was collected in red-topped tubes and in SSTs. Blood in SSTs was left in contact with the gel for 5 days. Serum organochlorine residue levels ([1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene] (DDE)) and polychlorinated biphenyls) in samples collected in red-topped tubes were highly correlated with levels measured in samples collected in SSTs (all Pearson r values were > or = 0.79). Postprandial and fasting organochlorine levels were also highly correlated (Pearson r values > or = 0.89). Our results indicate that timing of the collection of blood in relation to meals and use of SSTs to collect blood specimens did not greatly affect the relative classification of subjects with respect to serum level of DDE or polychlorinated biphenyls. The longer the specimen was in contact with the SST gel, however, the lower the level of organochlorine that was detected and, at least for DDE, the greater the misclassification caused.

Biological monitoring of diazinon exposure using saliva in an animal model.

Alternative biological monitoring methods are currently being pursued to better quantify pesticide exposures. In this study, the feasibility of using saliva as a tool for measuring diazinon exposure was determined in an animal model. Male Spraque-Dawley rats were dosed with 1 or 10 mg/kg diazinon by bolus intravenous injection. Time-matched saliva and arterial blood samples were collected from 10 to 250 min post administration. Diazinon was distributed and eliminated rapidly in rats following intravenous (iv) bolus injection, according to a two-compartmental pharmacokinetic analysis. Salivary concentration of diazinon showed a strong correlation with plasma concentration of diazinon. The saliva/plasma (S/P) concentration ratio of diazinon was not affected by administered dose, sampling time, or salivary flow rate, suggesting that salivary excretion of diazinon in rats is fairly constant. Diazinon concentrations in saliva were consistently lower than those in arterial plasma. The mean S/P concentration ratios of diazinon were 0.16 and 0.13 for 1 and 10 mg/kg iv bolus doses, respectively. It is most likely that the incomplete transfer of diazinon from plasma to saliva is due to protein binding of diazinon in plasma. If the protein-unbound fraction of diazinon in plasma is used to calculate the S/P ratio, the S/P concentration ratio of diazinon is close to unity. The results from this study support the conclusion that diazinon salivary concentrations not only can be used to predict the plasma levels of diazinon in rats, but also reflect the unbound fraction of diazinon in plasma.

Preparation and usage of a new solid phase micro-extraction membrane.

Liquid-liquid or solid phase extraction methods are widely used for isolating analytes from urine, blood and other samples. But the preparation procedures of the samples are laborious, intensive, and costly. In addition, the organic solvents used are toxic to both the human body and the environment. An accurate, simple and rapid method for analysis of some compounds is required for forensic, judicial, and clinical purposes. Solid phase micro-extraction membrane (SPMEM) is a new, simple and solventless preparation technique. It integrates sampling, extraction and concentration into a single step and has the advantages of both the solid phase micro-extraction (SPME) and membrane separation. In this paper, a new kind of membrane used for the solid phase micro-extraction was prepared with amide compounds. The extraction conditions such as adsorption time, desorption solvents, methods and time are studied and optimized. The dichlorvos in the blood, morphine and phenobarbital in the urine were perfectly separated by using this solid phase micro-extraction membrane, and were tested by gas chromatograph-mass spectrometer (GC-MS). All the data were acquired in scan mode except that of morphine which was obtained in a selected ion monitoring (SIM) mode. Ions used for identification were those with m/z 57, 115, 162, 215, 285.

German Environmental Survey 1998 (GerES III): environmental pollutants in blood of the German population.

The German Environmental Survey was conducted for the third time in 1998 (GerES III). The probability sample of about 4800 subjects was selected to be representative for the German population with regard to region (East-/West-Germany), community size, age (18 to 69 years) and gender. Blood samples were taken from each study participant and questionnaires were used to get exposure-related information. Cadmium, lead, mercury, hexachlorobenzene (HCB), hexachlorocyclohexane (alpha-HCH, beta-HCH, gamma-HCH), 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p, p'-DDE) and polychlorinated biphenyls (PCB-138, PCB-153, PCB-180) were analysed in whole blood to document the extent, distribution, and determinants of exposure of the general population to these substances. The geometric means of Cd, Pb, and Hg in blood amounted to 0.44, 31, and 0.58 microgram/l, respectively. Smokers showed a Cadmium level of 1.1 micrograms/l and non-smokers a level of 0.28 microgram/l. The geometric mean of lead was higher in the blood of males than of females (36 micrograms/l vs. 26 micrograms/l). The concentration of mercury in blood depends on fish consumption and the number of teeth with amalgam fillings. The mean concentrations of HCB and p, p'-DDE in blood were 0.44 microgram/l and 1.6 micrograms/l, respectively. In East-Germany (the former GDR) the DDE concentration in blood was more than twice as high as in West-Germany. Geometric means for PCB were 0.42, 0.68 and 0.44 microgram/l for PCB-138, PCB-153, and PCB-180, respectively. A marked increase of HCB, DDE and PCB levels with age could be observed. alpha-HCH and gamma-HCH could be detected in 1.7% and 5.2% of the samples only. beta-HCH was quantified in 34% of the samples with a 95th percentile of 0.5 microgram/l.

Pitfalls when determining tissue distributions of organophosphorus chemicals: sodium fluoride accelerates chemical degradation.

This paper describes the tissue distributions of dichlorvos, an organophosphate, and chlorpyrifos-methyl, an organophosphorothioate, in a male individual who died after ingesting an insecticidal preparation containing these chemicals and the results of an in vitro stability study on dichlorvos and chlorpyrifos-methyl in blood and buffers. Tiny amounts of dichlorvos, 0.067 and 0.027 mg/L, were detected in the vitreous humor and cerebrospinal fluid, respectively. Although dichlorvos (0.082-8.99 mg/L or mg/kg) was detected in the thoracic aortic blood, thoracic inferior vena caval blood, pericardial fluid, bile, and spleen, it was strongly suggested that it had diffused postmortem from the stomach, which contained 879 mg, because no dichlorvos was detected in the other blood samples and tissues tested. Substantial amounts (0.615-4.15 mg/L) of chlorpyrifos-methyl were detected in all blood samples, and the order of its concentrations was as follows: pulmonary vessel blood > thoracic inferior vena caval blood > blood in the right cardiac chambers > blood in the left cardiac chambers approximately thoracic aortic blood > right femoral venous blood. The total amount of chlorpyrifos-methyl in the stomach was 612 mg. However, it was strongly suggested that virtually no chlorpyrifos-methyl diffused from the stomach into surrounding fluids and tissues postmortem because no chlorpyrifos-methyl was detected in the bile and little was found in the pericardial fluids. Neither compound was detected in the urine. In vitro experiments showed that dichlorvos (10 mg/L) almost disappeared from fresh (pH 7.4) and acidified (pH 6.2) blood samples within 24 and 72 h, respectively. However, 53 and 77% of the original amount of dichlorvos in 0.05M phosphate buffers at pH 7.4 and 6.2 were detected 72 h later. Chlorpyrifos-methyl (1 mg/L) was very stable in blood samples, regardless of the pH, during the 72-h study period, but in the pH 7.4 and 6.2 phosphate buffers, approximately 80% of the original amount had degraded after 72 h. These results indicate that organophosphates are degraded more rapidly by esterase activities than by chemical mechanisms and that organophosphorothioates are hydrolyzed chemically in aqueous solutions but are very stable in biological specimens and not metabolized by esterases. When sodium fluoride was added to blood samples, dichlorvos degraded completely within 15 min, and chlorpyrifos-methyl became very unstable. Thus, when analyzing samples to detect organophosphorus chemicals, this common preservative should not be added to fluid specimens.

Pharmacokinetics of the chlorpyrifos metabolite 3,5,6-trichloro-2-pyridinol (TCPy) in rat saliva.

Biological monitoring (biomonitoring) to quantify systemic exposure to the organophosphorus insecticide chlorpyrifos (CPF) has historically focused on the quantitation of major CPF metabolites in urine. Noninvasive techniques are being advocated as novel means of biomonitoring for a variety of potential toxicants, including pesticides (like CPF), and saliva has been suggested as an ideal body fluid. However, in order to be acceptable, there is a need to understand salivary pharmacokinetics of CPF metabolites in order to extrapolate saliva measurements to whole-body exposures. In this context, in vivo pharmacokinetics of 3,5,6-trichloro-2-pyridinol (TCPy), the major chemical-specific metabolite of CPF, was quantitatively evaluated in rat saliva. Experimental results suggest that TCPy partitioning from plasma to saliva in rats is relatively constant over a range of varying physiological conditions. TCPy pharmacokinetics was very similar in blood and saliva (area under the curve values were proportional and elimination rates ranged from 0.007 to 0.019 per hour), and saliva/blood TCPy concentration ratios were not affected by TCPy concentration in blood (p = 0.35) or saliva flow rate (p = 0.26). The TCPy concentration in saliva was highly correlated to the amount of unbound TCPy in plasma (r = 0.96), and the amount of TCPy protein binding in plasma was substantial (98.5%). The median saliva/blood concentration ratio (0.049) was integrated as a saliva/blood TCPy partitioning coefficient within an existing physiologically based pharmacokinetic and pharmacodynamic (PBPK/PD) model for CPF. The model was capable of accurately predicting TCPy concentrations in saliva over a range of blood concentrations. These studies suggest that saliva TCPy concentration can be utilized to ascertain CPF exposure. It is envisioned that the PBPK/PD can likewise be used to estimate CPF dosimetry based on the quantitation of TCPy in spot saliva samples obtained from biomonitoring studies.

Comparative chlorpyrifos pharmacokinetics via multiple routes of exposure and vehicles of administration in the adult rat.

Chlorpyrifos (CPF) is a commonly used organophosphorus pesticide. A number of toxicity and mechanistic studies have been conducted in animals, where CPF has been administered via a variety of different exposure routes and dosing vehicles. This study compared chlorpyrifos (CPF) pharmacokinetics using oral, intravenous (IV), and subcutaneous (SC) exposure routes and corn oil, saline/Tween 20, and dimethyl sulfoxide (DMSO) as dosing vehicles. Two groups of rats were co-administered target doses (5 mg/kg) of CPF and isotopically labeled CPF (L-CPF). One group was exposed by both oral (CPF) and IV (L-CPF) routes using saline/Tween 20 vehicle; whereas, the second group was exposed by the SC route using two vehicles, corn oil (CPF) and DMSO (L-CPF). A third group was only administered CPF by the oral route in corn oil. For all treatments, blood and urine time course samples were collected and analyzed for 3,5,6-trichloro-2-pyridinol (TCPy), and isotopically labeled 3,5,6-trichloro-2-pyridinol (L-TCPy). Peak TCPy/L-TCPy concentrations in blood (20.2 micromol/l), TCPy/L-TCPy blood AUC (94.9 micromol/lh), and percent of dose excreted in urine (100%) were all highest in rats dosed orally with CPF in saline/Tween 20 and second highest in rats dosed orally with CPF in corn oil. Peak TCPy concentrations in blood were more rapidly obtained after oral administration of CPF in saline/Tween 20 compared to all other dosing scenarios (>1.5 h). These results indicate that orally administered CPF is more extensively metabolized than systemic exposures of CPF (SC and IV), and vehicle of administration also has an effect on absorption rates. Thus, equivalent doses via different routes and/or vehicles of administration could potentially lead to different body burdens of CPF, different rates of bioactivation to CPF-oxon, and different toxic responses. Simulations using a physiologically based pharmacokinetic and pharmacodynamic (PBPK/PD) model for CPF are consistent with these possibilities. These results suggest that exposure route and dosing vehicle can substantially impact target tissue dosimetry. This is of particular importance when comparing studies that use varying exposure paradigms, which are then used for extrapolation of risk to humans.