Biological monitoring: exquisite research probes, risk assessment, and routine exposure measurement

Association of bone mineral density with trichlorophenol: a population-based study

BACKGROUND

Trichlorophenols (TCPs) are metabolites of several organochlorine chemicals, including chlorobenzene, hexachlorocyclohexane, and chlorophenoxy acid, present in air, surface water, soil, and sediment. Many studies have shown that endocrine disruptors (EDs)may contribute to decreased bone mass and the increased risk of osteoporosis. However, the relationship between TCP and bone mineral density (BMD) has not been studied yet.

METHODS

We conducted a cross-sectional study by using data from the 2005-2010 National Health and Nutrition Examination Survey (NHANES). TCP levels were measured in urine samples from 3385 participants and bone mineral density was obtained by dual X-ray absorptiometry (DXA) lumbar spine and femur scanning. Multiple regression analysis, stratified analysis, curve fitting analysis, and trend tests were used to assess the relationship between TCP and BMD.

RESULT

After adjusting for confounding factors, the results of multiple regression analysis only showed that ln-2,4,5-TCP was negatively associated with BMD of lumbar spine. In stratified analyses, Male, Menstruating Female and Menopausal Female were divided into three groups for analysis. The results showed that ln-2,4,5-TCP and ln-2,4,6-TCP were not statistically associated with BMD in total femur, femoral neck, femoral tuberosity, intertrochanteric femur and lumbar spine, which was also confirmed by curve fitting analyses and trend tests.

CONCLUSION

This study demonstrated that 2,4,5-TCP and 2,4,6-TCP in urine samples were not significantly associated with BMD in the US population. Therefore, 2,4,5-TCP and 2,4,6-TCP may not be detrimental to BMD.

Concentrations of 2,4-Dichlorophenol and 2,5-Dichlorophenol in Urine of Korean Adults

Humans are exposed to the environmental pollutants 2,4-dichlorophenol (2,4-DCP) and 2,5-dichlorophenol (2,5-DCP) through air, the use of water and the consumption of products. In this study, we evaluated the urinary concentrations of these compounds in Korean people between the ages of 18 to 69 years, by making use of data from the Korean National Human Biomonitoring Survey that was completed in 2009. Of 1865 representative Koreans, 63.4% and 97.9% were found to have concentrations of 2,4-DCP and 2,5-DCP > 0.05 μg/L (limit of detection) in their urine, respectively. The geometric mean of urinary concentrations was 0.14 μg/L (confidence interval of 95% = 0.13–0.16) and 0.44 μg/L (confidence interval = 0.41–0.48), respectively. It was found that the adjusted proportional changes in 2,4-DCP concentrations were significantly associated with body mass index, whereas those of 2,5-DCP concentrations were influenced by place of residence. From these findings, it is evident that most adults in Korea have levels of 2,4-DCP and 2,5-DCP that are detectable in their urine and the burden of these compounds on their bodies varies depending on numerous demographic factors.

Urinary Levels of 4-Nonylphenol and 4-t-Octylphenol in a Representative Sample of the Korean Adult Population

4-Nonylphenol (4-NP) and 4-t-octylphenol (4-t-OP) are xenoestrogen compounds to which humans are exposed via contaminated food, water, and air. This study assessed the body burden of 4-NP and 4-t-OP in Koreans aged 18-69 years using data from the Korean National Human Biomonitoring Survey conducted in 2009. Based on data from 1865 representative Koreans, 83.2% and 91.8% had urinary 4-NP and 4-t-OP concentrations >0.05 ng/mL (limit of detection). Of the Korean adult population, the geometric mean urinary concentrations of 4-NP and 4-t-OP were 3.70 ng/mL (95% confidence interval (CI) = 3.20-4.27) and 0.60 ng/mL (95% CI = 0.55-0.66), respectively. Urine 4-NP concentrations were significantly associated with place of residence and smoking status, whereas urine 4-t-OP concentrations were not correlated with any of the demographic factors. These findings suggest that most Koreans have detectable levels of 4-NP and 4-t-OP in their urine and that the body burden of 4-NP, but not 4-t-OP, varies according to some demographic factors.

Urinary concentrations of trichlorophenols in the Korean adult population: results of the National Human Biomonitoring Survey 2009

Trichlorophenols such as 2,4,5-trichlorophenol (2, 4,5-TCP) and 2,4,6-trichlorophenol (2,4,6-TCP) are organochlorine compounds to which the general public can be exposed via contaminated food, water, and air. This study assessed exposure to 2,4,5-TCP and 2,4,6-TCP in Koreans age 18-69 years based on the Korean National Human Biomonitoring Survey conducted in 2009. Using data from 1,865 representative Koreans, we found that the geometric mean urinary concentrations of 2,4,5-TCP and 2,4,6-TCP were 83.4 pg/mL [95 % confidence interval (CI)=78.6-88.6] and 0.39 ng/mL (95 % CI=0.35-0.42), respectively. The creatinine-adjusted geometric mean 2,4,5-TCP and 2,4, 6-TCP levels were 78.8 ng/g creatinine (95 % CI=73.8-84.1) and 0.36 μg/g creatinine (95 % CI=0.33-0.40), respectively. Of the Korean adult population, about 67.5 and 87.5 % had respective urine 2,4,5-TCP and 2,4,6-TCP concentrations >0.05 ng/mL (the limit of detection, LOD). Urine 2,4,5-TCP concentrations were significantly associated with age and place of residence, whereas urine 2,4,6-TCP concentrations were higher in rural residents. These findings suggest that most Koreans had detectable levels of 2,4,5-TCP and 2,4,6-TCP in their urine and that the body burden of 2,4,5-TCP and 2,4,6-TCP varied according to demographic and geographic factors.

Toxicological profile of chlorophenols and their derivatives in the environment: the public health perspective

Chlorophenol compounds and their derivatives are ubiquitous contaminants in the environment. These compounds are used as intermediates in manufacturing agricultural chemicals, pharmaceuticals, biocides, and dyes. Chlorophenols gets into the environment from a variety of sources such as industrial waste, pesticides, and insecticides, or by degradation of complex chlorinated hydrocarbons. Thermal and chemical degradation of chlorophenols leads to the formation of harmful substances which constitute public health problems. These compounds may cause histopathological alterations, genotoxicity, mutagenicity, and carcinogenicity amongst other abnormalities in humans and animals. Furthermore, the recalcitrant nature of chlorophenolic compounds to degradation constitutes an environmental nuisance, and a good understanding of the fate and transport of these compounds and their derivatives is needed for a clearer view of the associated risks and mechanisms of pathogenicity to humans and animals. This review looks at chlorophenols and their derivatives, explores current research on their effects on public health, and proffers measures for mitigation.

Evolution of phage display: from bioactive peptides to bioselective nanomaterials

BACKGROUND

New phage-derived biorecognition nanomaterials have emerged recently as a result of the in-depth study of the genetics and structure of filamentous phage and the evolution of phage display technology.

OBJECTIVE

This review focuses on the progress made in the development of these new nanomaterials and discusses the prospects of using phage as a bioselectable molecular recognition interface in medical and technical devices.

METHODS

The author used data obtained both in his research group and sourced using Science Citation Index (Web of Science) search resources.

RESULTS/CONCLUSION

The merging of phage display technologies with nanotechnology over the past few years has proved promising and has already shown its vitality and productivity by contributing vigorously to different areas of medicine and technology, such as medical diagnostics and monitoring, molecular imaging, targeted drug and gene delivery, vaccine development, as well as bone and tissue repair.

Fermentation reactor coupled with capillary electrophoresis for on-line bioprocess monitoring

In this paper, a filter probe integrated into a computerized pneumatic sampler for capillary electroseparations was developed for an on-line monitoring of bioprocesses. The optimization of the performance of the coupled system was done by using a response surface modeling and three-level two-factor design. The resolution was found to be the most important parameter influencing the performance of an on-line analysis of the microbial metabolism. For the on-line analysis the migration time and detection limit were also found to be important parameters. Different parameters were combined by using an overall desirability function to find optimum conditions for all parameters. The equipment with an optimized separation protocol was used to monitor the bioaccumulation of Cu, Zn, Co and Cd (with detection limits 0.46, 0.37, 1.2, 0.84 mM correspondingly) by the Rhodococcus sp. bacteria isolated from the highly polluted technogenic soil of northeastern Estonia during a 2-week experiment.

Biomonitoring human exposure to organohalogenated substances by measuring urinary chlorophenols using a high-throughput screening (HTS) immunochemical method

The widespread contamination of the environment by persistent organochlorinated substances is well-known. High-throughput immunochemical methods may improve routine assessment of the exposure of the population to these chemicals by analyzing urinary biomarkers. Trichlorophenols (TCP) have often been considered as biomarkers of many organochlorinated compounds. With the aim to assess exposure of the population to these substances a high-throughput immunosorbent solid-phase extraction (HTS-IS-SPE) procedure coupled to ELISA for simultaneous analyses of 2,4,6-TCP immunoreactivity equivalents (2,4,6-TCP-IR equiv) in multiple hydrolyzed urine samples has been developed. Around 100 urine samples can be processed simultaneously with an inter- and intraassay precision lower than 23% CV and a limit of detection of 0.3 microg L(-1). The analyses by HTS-IS-SPE-ELISA and HTS-IS-SPE-GC/MS of urine samples (N = 117) collected from three different population groups point to a broad exposure of the Catalonian population to organohalogenated substances including the recently emerging organobrominated pollutants. Environment and edible products seem to be the most likely sources of exposure, since excretion of 2,4,6-TCP-IR equiv has been found to be independent from the occupational sector. An excellent correlation was observed between the 2,4,6-TCP-IR equiv determined by HTS-IS-SPE-ELISA and the concentrations measured by HTS-IS-SPE-GC/MS (R2 = 0.912). The results show that immunochemical screening methods, based on the quantification of urinary biomarkers, can be excellent tools for exposure assessment. The HTS-IS-SPE-ELISA presented here has proved to be efficient, precise, accurate, rapid, and specific, which opens up the possibility for a broad variety of applications where routine testing of large number of samples is required.

Strategies for continuous on-line high performance liquid chromatography coupled with diode array detection and electrospray tandem mass spectrometry for process monitoring of sulphonated azo dyes and their intermediates in anaerobic–aerobic bioreactors

On-line HPLC with diode array detection (DAD) coupled to electrospray tandem mass spectrometry (ESI-MS/MS) is presented as an integrated quality control and process integrated optimisation tool for the continuous monitoring of sulphonated azo dyes (SADs) and their intermediates in anaerobic and aerobic bioprocesses. Ion-pair RP-HPLC is found out to be more suitable for simultaneous monitoring of aromatic amines (AAs), sulphonated aromatic amines (SAAs) and sulphonated azo dyes in comparison to RP-HPLC with polar embedded phases. Monitoring of the anaerobic degradation of the diazo Reactive Black 5 displays the dependency of a two stage azo group reduction mechanism on the redox potential of the bioreactor. An autoxidation sensitive intermediate released from the anaerobic reduction is characterised by ESI-MS/MS for the first time. The functionality of the method is demonstrated by the control and evaluation of selective adaptation of bacteria to certain pollutants and the identification of unknown intermediates causing re-gaining colour released from azo dye treatment.

Biological monitoring of exposure: trends and key developments

The concept of biological monitoring (BM) has gained the special interest of individual scientists and international organizations. Today, when analytical problems have almost ceased due to new laboratory techniques and quality assurance systems, the methods for interpretation of results have become the most important issue. There are important discrepancies regarding the role of biological monitoring of occupational exposure between Europe and the United States. BM has been an important tool of medical health surveillance in the European countries. In the United States it belongs rather to the field of occupational hygiene. It seems that both the approaches can be accepted. More attention should be paid to the development of the truly health-based biomarkers of exposure based on the dose-effect and dose-response relationships. New areas of application of BM of occupational exposure include determination of DNA and protein adducts, unchanged volatile organic compounds in urine, monitoring of exposure to pesticides, antineoplastic drugs, hard metals, and polycyclic aromatic hydrocarbons. In the general environment BM is the most valuable tool for acquiring knowledge of current levels of internal exposure to xenobiotics, identifying the hot spots and developments in trends of exposure. BM can provide policy makers with more accurate information on the control measures undertaken. At present, the main areas include heavy metals, persistent organic pollutants and pesticides. BM of chemical exposure has become increasingly important in the assessment of the health risk in occupational and environmental medicine. Therefore it would be worthwhile to include BM in the curricula for the training of occupational hygienists.

Multi-element speciation of metalloproteins in fish tissue using size-exclusion chromatography coupled "on-line" with ICP-isotope dilution-time-of-flight-mass spectrometry

An on-line isotope dilution (ID) method in combination with the coupling of size-exclusion high-performance liquid chromatography (SE-HPLC) to an axial inductively coupled plasma time-of-flight mass spectrometer (ICP-TOFMS) was applied to the quantitative speciation of Cu, Zn and Cd in carp and eel cytosols. Quantitative information on the distribution of essential and toxic metals between the different molecular weight fractions in kidney cytosols of control and Cd exposed carp was obtained with species-unspecific spiking by post-column addition of the enriched isotopes 65Cu, 67Zn and 106Cd. The isotope ratios 63Cu/65Cu, 64Zn/67Zn and 114Cd/106Cd, were monitored by ICP-TOFMS in transient signal mode. The determination of the total cytosolic element concentration was performed by flow injection conventional nebulization ICP-TOFMS. Speciation differences were encountered between control and Cd-stressed carp, indicating that quantitative speciation studies might be useful for ecotoxicological and biomonitoring purposes. Application of this methodology to quantitation of metals associated with metallothioneins (MT) in European eel, sampled at three different sites in Flanders, Belgium was also addressed. A significant increase of the amount of Cd, Cu and Zn bound to hepatic MT was observed with the increase of the total metal and MT concentrations of hepatic eel tissue.