J. Xenobiot., Volume 2, Issue 1 (January 2012) – 10 articles

Polychlorinated biphenyls (PCBs) were primarily used in transformers and capacitors, lubricants, flame retardants, plasticizers, paint, carbonless papers, etc. These are capable of long-range atmospheric transport and have been designated as persistent organic pollutants by the Stockholm Convention. Due to their characteristic properties, PCBs are found worldwide in all environmental matrices (including human) and biota. Soils are usually considered to be the source as well as sink for environmental pollutants, with cumulative effects of long-range atmospheric transport and local sources. Around the world, comparatively higher concentrations of PCBs have been reported in urban soils than suburban or rural soils. Higher amount of PCBs in urban soils may cause toxicological health risks to urban residents through ingestion, inhalation and skin contact. This paper presents the PCB distribution in soils from Delhi, India, and exposure risk estimates for human health through soil ingestion. The concentration of ΣPCBs ranged between 1.08-100.67 ng g^–1 (mean 21.16 ng g^–1±5.24 ng g^–1), which was much lower than the Canadian soil quality guideline value of 1.3 mg/kg or 1300 ng g^–1. Human health risk estimates through the soil ingestion pathway were made in terms of lifetime average daily dose (LADD), incremental lifetime cancer risks and non-carcinogenic hazard quotient (HQ). The LADD for Delhi adults and children was 3.02x10^–8 mg kg^–1 d^–1 and 1.57x10^–7 mg kg^–1 d^–1, respectively, which corresponds to toxic equivalent quotients (TEQ) intake of 0.105 pg TEQ kg^–1 d^–1 (0.735 pg TEQ kg^–1 week^–1) and 0.543 pg TEQ kg^–1 d^–1 (3.801 pg TEQ kg^–1 week^–1), respectively. The estimated LADD for Delhi residents was lower than the acceptable intake values recommended by the World Health Organization (1 pg TEQ kg^–1 d^–1), the European Commission (14 pg TEQ kg^–1;1 week^–1) and by the Japanese government (4 pg TEQ kg^–1 d^–1). The probability of cancer risk ranges from 6.04x10^–8 (ΣPCBs) to 1.57x10^–5 (ΣTEQ) and 3.13x10–7 (ΣPCBs) to 8.15x10–5 (ΣTEQ) for adults and children, respectively, and was within acceptable ranges of 10^–6 to 10^–4. The non-carcinogenic risk in terms of health HQ was 0.105 and 0.330 for adults and children, respectively, which was lower than the acceptable limit of 1. The study found lower concentrations of PCBs than guideline values and low health risk estimates through the soil ingestion pathway within acceptable levels, indicating a minimum risk for Delhi residents. Full article

Microcystins (MCs) are toxins produced by cyanobacteria during the blooms that could accumulate in aquatic animals and be relocated to higher trophic levels. Adenosine triphosphate (ATP) acts as an excitatory neurotransmitter and/or a neuromodulator in the extracellular space playing important roles in physiological and pathological conditions. The aim of this study was, therefore, to evaluate the acute effects of different concentrations of MC-LR on nucleoside triphosphate diphosphohydrolases and 5’-nucleotidade in adult zebrafish (Danio rerio) brain membranes. The results have shown no significant changes in ATP, adenosine diphosphate (ADP) and adenosine monophosphate (AMP) hydrolysis in zebrafish brain membranes. MC-LR in vitro also did not alter ATP, ADP and AMP hydrolysis in the concentrations tested. These findings show that acute exposure to MC-LR did not modulate ectonucleotidase activity in the conditions tested. However, additional studies including chronic exposure should be performed in order to achieve a better understanding about MC-LR toxicity mechanisms in the central nervous system. Full article

Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzo-p-furans (PCDFs) are unintentionally formed during inefficient combustions and as a by-product. Due to their resistance to degradation and their toxic effect on health, PCDD/Fs are listed by the Stockholm Convention as persistent organic pollutants (POPs). Once released into the atmosphere, most of them are adsorbed to air particles and transported away from sources in atmosphere. India signed the Stockholm Convention India agreeing thereby to reduce and eliminate the use of POPs. The German agency for Technical Cooperation helped develop facilities for monitoring POPs at a national level in Delhi. This paper presents the data generated during a training assignment for Central Pollution Control Board officials at the German laboratory. Air borne particulate matter (<PM₁₀) was collected from 6 different locations in Delhi, India and analyzed in a German laboratory for 17 congeners of PCDD/Fs. The concentrations of ΣPCDD/Fs ranged between 1720-9010 fg m^-3 (mean 5559 fg m^-3) and their toxic equivalency values ranged from 67 to 460 fg I-toxic equivalent quantities (TEQ) m^-3, with an average of 239 fg I-TEQ m^-3 which was lower than the ambient air standards. The dominant congeners were octachlorinated dibenzo-p-dioxin (OCDD), octachlorinated dibenzo-p-furans (OCDF), 1,2,3,4,6,7,8-heptachlorinated dibenzo- p-furans, and 1,2,3,4,6,7,8-heptachlorinated dibenzo-p-dioxin. The contributions of individual homologs for ΣPCDDs/Fs I-TEQ was in the order of OCDD (31%)>HCDF (21%)>hexachlorodibenzofurans (13%)=OCDF (13%)> HCDF (12%) and other individual congeners contribute less than 5%. High chlorinated congeners contributed with more than 80% for ΣPCDD/Fs I-TEQ. Rough estimates of tolerable daily intake (TDI) shows low health risk of exposure to ΣPCDD/Fs with inhalation of 0.098 pg I-TEQ kg¹day¹ for adult and 0.152 pg TEQ kg^-1day^-1 for children, which is much lower than World Health Organization recommended TDI for dioxins. Full article

Polychlorinated biphenyls (PCBs), hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethane (DDT) are toxic, persistent and bioaccumulative long-range atmospheric transport pollutants. These are transported worldwide affecting remote regions far from their original sources, and can transfer into food webs with a wide range of acute and chronic health effects. India ratified the Stockholm Convention with the intention of reducing and eliminating persistent organic pollutants (POPs), and encouraged the support of research on POPs. Despite the ban and restriction on the use of these chemicals in India, their contamination of air, water, sediment, biota and humans has been reported. In this study, surface water samples were collected during January 2012 from the Yamuna River in Delhi, India, and analyzed for PCBs and organochlorine pesticides (OCPs). The concentrations of ΣPCBs and ΣOCPs ranged between 2-779 ng L^–1 and from less than 0.1 to 618 ng L^–1 (mean 99±38 ng L^–1 and 221±50 ng L^–1, respectively). The PCB homolog was dominated by 3-4 chlorinated biphenyls. In calculating the toxicity equivalent of dioxin-like PCBs (dl-PCBs)using World Health Organization toxic equivalency factors, dl-PCBs accounted for 10% of a total of 27 PCBs. The concentration of ΣHCH ranged between less than 0.1 and 285 ng L^–1 (mean 151±32 ng L^–1). However, ΣDDTs concentrations varied between less than 0.1 and 354 ng L^–1 (mean 83±26 ng L^–1). The concentrations were lower than the US guideline values; however, levels of lindane exceeded those recommended in guidelines. Further in-depth study is proposed to determine the bioaccumulation of these pollutants through aquatic biota to assess the risk of contaminants to human health. Full article

The sublethal toxicity of diazinon to the adult African toad, Bufo regularis was assessed using an integration of biomarkers. Changes in acetylcholinesterase (AChE), corticosterone and total protein levels were assessed in the serum, brain, liver, lungs and gastrointestinal tract (GIT) and the results supported by bioaccumulation data. The biomarkers were chosen as indicators of key physiological functions: AChE for neurotoxicity, corticosterone and total protein levels as indicators of oxidative stress. Toads were exposed to 0.01, 0.02, 0.03 and 0.04 g/L for 28 days. Brain AChE activity reduced by 96% in the highest concentration (0.04 g/L) compared to the control brain. Similarly, AChE activities in serum, liver, lungs and GIT tissues (88%, 88%, 87, 87% umg-1 protein respectively) were also inhibited in the toads. Corticosterone and total protein levels in the tissues decreased compared to the control. The accumulation results obtained showed accumulation in the tissues (liver>serum>brain> lung>GIT), with a direct relationship between tissue concentration and changes in the biochemical indices. The alterations in all the indices were significantly concentration dependent. The biomarkers described in this study could be useful complementary indices in the risk assessment of diazinon pesticide. Full article

Untreated detergent bearing wastes discharged into the environment are sources of linear alkylbenzene sulfonate (LAS). Detergent wastes usually do not contain nitrogen or contain very low amounts. Biostimulation by introducing limiting nutrient element can be useful in biotreatment of such waste. The effect of inorganic and organic nitrogen supplements on aerobic degradation of LAS by LAS-utilizing bacteria was examined. Phosphate-buffered LAS mineral media were prepared and supplemented with different nitrogen sources: NPK fertilizer (inorganic) and urea fertilizer (organic). Individual and various consortia of pure cultures of Alcaligenes odorans, Citrobacter diversus, Micrococcus luteus and Pseudomonas putida, previously isolated from a detergent effluent polluted stream, were used. Biodegradation of LAS was monitored in terms of half-life (t½) of the surfactant. The rates of biodegradation by the consortia can be ranked as: 4-membered (t½=8-12 days) >3-membered (t½=8-13 days) >2-membered consortia (t½=10-15 days) >individuals (t½=9-16 days). The inorganic nitrogen source enhanced utilization of the surfactant, while organic nitrogen supplementation generally slowed degradation of the surfactant. In undertaking biotreatment of detergent bearing effluent, inorganic nitrogen should be used as biostimulant. Full article

Pharmaceutical substances represent a risk for aquatic environments and their potential impacts on the receiving environment are poorly understood. Municipal effluents are important sources of contaminants including common pharmaceuticals like anti-inflammatory and anti-convulsive substances. The removal of pharmaceuticals, particularly those highly soluble can represent a great challenge to conventional wastewater treatment processes. Hydrophilic drugs (e.g. acidic drugs) have properties that can highly influence removal efficiencies of treatment plants. The performance of different wastewater treatment processes for the removal of specific pharmaceutical products that are expected to be poorly removed was investigated. The obtained results were compared to inherent properties of the studied substances. Clofibric acid, carbamazepine, diclofenac, ibuprofen and naproxen were largely found in physicochemical primary-treated effluents at concentrations ranging from 77 to 2384 ng/L. This treatment type showed removal yields lower than 30%. On the other hand, biological treatments with activated sludge under aerobic conditions resulted in much better removal rates (>50% for 5 of the 8 studied substances). Interestingly, this latter type of process showed evidence of selectivity with respect to the size (R2=0.7388), solubility (R2=0.6812), and partitioning (R2=0.9999) of the removed substances; the smallest and least sorbed substances seemed to be removed at better rates, while the persistent carbamazepine (392 ng/L) and diclofenac (66 ng/L) were poorly removed (<10%) after biological treatment. In the case of treatment by aerated lagoons, the most abundant substances were the highly soluble hydroxy-ibuprofen (350-3321 ng/L), followed by naproxen (42-413 n/L) and carbamazepine (254-386 ng/L). In order to assess the impacts of all these contaminants of various properties on the environment and human health, we need to better understand the chemical and physical transformations occurring at the treatment plant and in the receiving waters. Full article

In this study, we assessed in vitro the effects of PCDD/Fs on the NK-like cell activity in Eisenia andrei earthworms using flow cytometry for analysis. NK-like coelomocytes isolated from E. andrei and used as effectors were exposed to various concentrations of PCDDs/Fs mixture, C1 (6.25x10-3 ng 2378- TCDD/mL), C2 (12.5x10-3 ng 2378-TCDD/mL) and C3 (25x10-3 ng 2378-TCDD/mL), before adding them to human tumoral cells (K562) used as targets. We evaluated the percentage of targets lysed by Nk-like cells. The results showed a significant stimulation of the NKlike activity at C3 when PCDD/Fs were not removed from effectors before contact with targets, while no effects were noted when the effectors were washed (PCDD/Fs removed) or fixed. Assessment of the viability of the targets (K562), exposed alone and separately from effectors, to the three concentrations of PCDD/Fs, C1, C2 and C3, showed that all these concentrations were cytotoxic for K562. Results suggest that PCDD/Fs concentrations tested in this assay may be considered too low to induce suppressive effects on the immune function such as the NK-like activity in E. andrei earthworms. Full article

Phenol and phenolic compounds are aromatic pollutants that inhibit biological treatment of wastewaters. Penicillium chrysogenum var. halophenolicum is a halotolerant fungus that previously showed the ability to degrade phenol and resorcinol in high salinity conditions. The presence of the penicillin biosynthetic cluster in P. chrysogenum var. halophenolicum was recently described. In this article, we examined the expression of pcbAB, pcbC and penDE, genes responsible for δ-(L-α-aminoadipyl)-L-cysteinyl-D-valine synthetase, isopenicillin N synthase and isopenicillin N acyltransferase activities, respectively, in P. chrysogenum var. halophenolicum. A quantitative PCR (qPCR) approach was used to determine how these genes were expressed in media with 2% and 5.9% NaCl supplemented with phenol, catechol, hydroquinone and resorcinol as the sole carbon source. The effect of salt on the capability of P. chrysogenum var. halophenolicum to degrade aromatic compounds was measured using HPLC. qPCR analysis of RNA extracted from P. chrysogenum var. halophenolicum indicated that the expression levels of pcbAB, pcbC and penDE decreased in high saline concentrations compared to the levels expressed in media with glucose. High concentrations of salt significantly repress the expression of pcbAB and penDE. The pcbC gene was expressed differentially in catechol containing medium. There was no evident relationship between the expression levels of penicillin biosynthetic genes and yields of penicillin. Meanwhile, the presence of phenol and phenolic compounds seems to positively influence the antibiotic production; high concentrations of salt stimulated penicillin production. These results support the hypothesis that phenol, phenolic compounds and high concentrations of salt could act like a stress factor for P. chrysogenum var. halophenolicum resulting in higher yields of β-lactam antibiotic production. Full article