Organochlorine pesticides and their markers of exposure in serum and urine of children from a nodding syndrome hotspot in northern Uganda, east Africa.

Nodding syndrome (NS) is a neurologic disorder of unknown etiology characterized by vertical head nodding that has affected children aged 5-18 years in East Africa. Previous studies have examined relationships with biological agents (e.g., nematodes, measles, and fungi), but there is limited data on the possible contributions of neurotoxic environmental chemicals frequently used as pesticides/insecticides to the development and progression of this disorder. We examined the levels of persistent organochlorine pesticides (OCPs) in children (5-18 years old) from Kitgum District, Northern Uganda. These children previously lived in internally displaced people's (IDP) camps, where they were exposed to various health risks, including contaminated food and water. Exposure to OCPs through contaminated food and water is postulated here as a potential contributor to NS etiology. We analyzed serum (n = 75) and urine (n = 150) samples from children diagnosed with NS, and from seizure-free household controls (HC), and community controls (CC). Samples were extracted using solid-phase extraction (SPE) and extracts were analyzed for OCPs using gas chromatography with a triple quadrupole mass spectrometry (GC-MS/MS). Mean levels of total (∑) ∑OCPs in serum samples from NS, HC and CC subjects were 23.3 ± 2.82, 21.1 ± 3.40 and 20.9 ± 4.24 ng/mL, respectively, while in urine samples were 1.86 ± 1.03, 2.83 ± 1.42, and 2.14 ± 0.94 ng/mL, respectively. Correlation and linear regression analysis indicated that potential markers for ∑hexachlorocyclohexanes (HCHs), ∑chlordane compounds (CHLs), ∑endosulfan and ∑dichlorodiphenyltrichloroethanes (DDTs) were γ-HCH, heptachlor-exo-epoxide, endosulfan-α and p,p'-DDD in NS cases while in controls were α -HCH, heptachlor, endosulfan-α and p,p'-DDE, respectively. Since, in some instances, higher OCP levels were found in controls vs. NS cases, we conclude that exposure to organochlorine pesticides is unlikely to be associated with the etiology of NS.

Evaluation of layered double hydroxide/graphene hybrid as a sorbent in membrane-protected stir-bar supported micro-solid-phase extraction for determination of organochlorine pesticides in urine samples.

In this work, the potential of layered double hydroxide/graphene (LDH-G) hybrid as a sorbent for extraction and preconcentration of fifteen organochlorine pesticides (OCPs) in urine samples was evaluated. The LDH-G hybrid was synthesized by co-precipitation method and it was then characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The sorbent was then employed in membrane-protected stir-bar supported micro-solid-phase extraction (SB-µ-SPE) of OCPs in urine samples. This extraction approach is highly suitable for the samples representing matrix complexity such as urine because the sorbent is effectively protected inside the membrane. The extracted samples were analyzed by gas chromatography mass spectrometry. The factors that affect the performance of SB-µ-SPE were suitably optimized. This method demonstrated good linearity with coefficients of determination up to 0.9996. The limits of detection ranged between 0.22 and 1.38ngmL-1. The RSD values for intra and inter-day precision were also in a satisfactory range (2.7-9.5%).

Interaction Effects between Organochlorine Pesticides and Isoflavones In Vitro and In Vivo.

Organochlorine pesticides (OCPs) have caused increasing global concern due to their high toxicity, persistence, bioaccumulation, and significant adverse effects on human health. This study was to explore the interaction effects between OCPs and isoflavones. Six kinds of OCPs and 2 kinds of isoflavones-genistein and daidzein were included to study their effect on MCF-7 cells in vitro. Eighty-one female Sprague-Dawley rats were randomized to 9 groups according to factorial design to study the interaction effect between isoflavones and γ-HCH. Compared to organochlorine pesticides alone group, proliferation rate of MCF-7 cells was lower in 100 µmol/L genistein + organochlorine pesticides and 100 µmol/L daidzein + organochlorine pesticides group (p < 0.05). In vivo study showed that there are interaction effects on kidney weight and liver weight when treated with isoflavones and γ-HCH. The changes in uterine morphology and positive expression of ERα showed inhibition effects between isoflavones and γ-HCH. In conclusion, the data suggests that there are interactions between isoflavones and OCPs in vitro and in vivo.

Association between organochlorine pesticide exposure and thyroid hormones in floriculture workers.

Several studies have suggested that exposure to DDT may be related to changes in thyroid hormone levels in animals and humans, even though results across studies are inconsistent. The aim of this study was to assess the association between exposure to p,p'-DDE (a stable metabolite of DDT) and serum levels of thyroid hormones in floriculture workers. A longitudinal study was conducted on 136 male subjects from the States of Mexico and Morelos, Mexico, who were occupationally exposed to pesticides, during agricultural periods of high (rainy season) and low (dry season) levels of pesticide application. Using a structured questionnaire, a survey was carried out on socio-demographic characteristics, anthropometry, clinical history, alcohol and tobacco consumption, residential chemical exposure, and occupational history. Blood and urine samples were collected to determine serum levels of TSH, total T3, total T4, and p,p'-DDE, and metabolites of organophosphate pesticides (OP), respectively. The analysis of the associations between p,p'-DDE levels and thyroid hormone profile adjusting by potential confounding variables including urinary OP metabolites was carried out using multivariate generalized estimating equation (GEE) models. Our results showed that the geometric means of p,p'-DDE levels were 6.17 ng/ml and 4.71 ng/ml in the rainy and dry seasons, respectively. We observed positive associations between the serum levels of p,p'-DDE and those of total T3 (ß=0.01, 95% CI: -0.009, 0.03), and total T4 (ß=0.08, 95% CI:0.03, 0.14) and negative but no significant changes in TSH in male floricultural workers, supporting the hypothesis that acts as thyroid disruptor in humans.

Human biomonitoring in the Czech Republic: an overview.

In the Czech Republic, the Human Biomonitoring Project (CZ-HBM) was launched in 1994 as an integral part of the nationwide Environmental Health Monitoring System (EHMS). Until now, the HBM covers two time periods: the first covered 1994-2003 and the second, 2005-2009. Altogether three population groups were included in the HBM: adults (blood donors aged 18-58 years), children aged 8-10 years, and breastfeeding primiparas. Sampling is organized on a yearly basis. Altogether three groups of biomarkers were analyzed: (a) selected heavy metals (Pb, Cd, Hg) and essential elements (Cu, Se, Zn) in blood and urine of adults and children, (b) indicator PCBs, DDT, DDE, HCB and HCHs in human milk and blood serum of adults and (c) cytogenetic changes in peripheral lymphocytes in blood of adults and children. This paper is focused on the general design of the CZ-HBM, the trends over time, and reference values. A significant downward time trend was observed for the blood lead levels in adults and children. Increased urinary cadmium levels were observed in Czech children compared to German children. The blood and urinary mercury levels were higher in women than in men. The levels of indicator PCB congeners in the Czech human milk samples were still higher than in most other European countries, because of existing hot spots. The levels of organochlorine pesticides showed a substantial continuous downward trend.

Monitoring of occupational exposure to volatile organohalogen solvents (VOXs) in human urine samples of dry-cleaner workers by TLHS-DAI-GC-ECD procedure.

Chlorinated hydrocarbon solvents are often used for dry-cleaning clothes in the laundry industry. The object of this study was to monitor the occupational exposure of dry-clean employees coming into contact with VOXs. Twenty five workers collected their urine samples before the work shift, after 4 h of work and after the work shift. The analyses of urine samples and solvents used in dry-cleaning were performed using TLHS-DAI-GC-ECD. Chloroform was detected in all urine samples, and dichloromethane and tetrachloroethene in nearly all urine samples collected before and after the work shift. The concentrations of the compounds determined in urine samples were higher at the end of the workday in directly exposed individuals. Concentrations of the compounds determined in urine samples depended mainly on the type of activities carried out at the dry-cleaning establishments.

Monitoring of occupational exposure to tetrachloroethene by analysis for unmetabolized tetrachloroethene in blood and urine in comparison with urinalysis for trichloroacetic acid.

OBJECTIVE: The present study was initiated to examine a quantitative relationship between tetrachloroethene (TETRA) in blood and urine with TETRA in air, and to compare TETRA in blood or urine with trichloroacetic acid (TCA) in urine as exposure markers. METHODS: In total, 44 workers (exposed to TETRA during automated, continuous cloth-degreasing operations), and ten non-exposed subjects volunteered to participate in the study. The exposure to vapor was monitored by diffusive sampling. The amounts of TETRA and TCA in end-of-shift blood and urine samples were measured by either head-space gas chromatography (HS-GC) or automated methylation followed by HS-GC. The correlation was examined by regression analysis. RESULTS: The maximum time-weighted average (TWA) concentration for TETRA-exposure was 46 ppm. Regression analysis for correlation of TETRA in blood, TETRA in urine and TCA in urine, with TETRA in air, showed that the coefficient was largest for the correlation between TETRA in air and TETRA in blood. The TETRA in blood, in urine and in air correlated mutually, whereas TCA in urine correlated more closely with TETRA in blood than with TETRA in urine. The TCA values determined by colorimetry and by the GC method were very similar. The biological marker levels at a hypothetical exposure of 25 ppm TETRA were substantially higher in the present study than were the levels reported in the literature. Possible reasons are discussed. CONCLUSIONS: Blood TETRA is the best marker of occupational exposure to TETRA, being superior to the traditional marker, urinary TCA.

Effects of exposure to low concentrations of chlorinated hydrocarbons on the kidney and liver of industrial workers.

An assessment has been made of biochemical alterations in renal and hepatic functions of 73 male operators employed for an average of 8.2 years (range 0.5-23 years) in a chemical plant producing chlorinated hydrocarbons. Exposure to allyl chloride (AC), 1,3-dichloropropene (DCP), epichlorohydrin (ECH), and hexachlorocyclopentadiene (HEX) has regularly been determined by personal air monitoring since 1980. Although exposures to DCP and ECH were well below currently accepted maximum allowable concentrations (MACs), relatively high exposures to AC and HEX, occasionally exceeding the MAC, have been measured. The results of the kidney and liver function tests were compared with those of a control group comprising 35 men employed at the materials division and not occupationally exposed to chemicals. Biochemical alterations of liver function were assessed by determination in serum of alanine and aspartate aminotransferases (ALAT, ASAT), alkaline phosphatase (AP), total bilirubin (BIL), gamma-glutamyltranspeptidase (GGT), lactate dehydrogenase (LDH), and total bile acids (SBA). No differences between the exposed group and the control group were found. Nor were differences found in biochemical tests for renal tubular damage (urinary alanine aminopeptidase (AAP) and N-acetyl-beta-D-glucosaminidase (NAG) and renal tubular function (urinary retinol binding protein (RBP). Total urinary protein and albumin excretion were measured to assess the integrity of the glomerulus. Urinary total protein did not differ between the groups, but urinary albumin, although within normal limits in both groups, was significantly higher (p < 0.02) in the exposed group. This difference in urinary albumin could not simply be explained by exposure to chlorinated hydrocarbons because albumin concentrations did not correlate with the duration of employment. It is concluded that long term exposure to concentrations of AC, DCP, ECH, or HEX below or near the current limit threshold value does not lead to clinically significant effects on kidney and liver.

1,2-Dichloropropane: metabolism and fate in the rat.

1. The metabolism of 1,2-dichloropropane in the rat has been investigated. The major urinary metabolite has been isolated and identified as N-acetyl-S-(2-hydroxypropyl)cysteine. Two minor metabolites of 1,2-dichloropropane have been identified as beta-chlorolactate and N-acetyl-S-(2,3-dihydroxypropyl)cysteine. 2. The fate of 1-chloro-2-hydroxypropane, a proposed intermediate metabolite of 1,2-dichloropropane, has been investigated. Apart from its known urinary metabolite, N-acetyl-S-(2-hydroxypropyl)cysteine, two oxidative metabolites were detected. These were identified as beta-chlorolactaldehyde and beta-chlorolactate. 3. A pathway is proposed for the metabolism and fate of 1,2-dichloropropane in the rat. This accounts for previous observations made for the fate of radioactivity from administration of 1,2-dichloro[1-14C]propane. 4. The microbial and mammalian metabolism of several halogen-containing foreign compounds is discussed.