Nguyen Phuc Cam Tu

Contamination by trace elements at e-waste recycling sites in Bangalore, India.

The recycling and disposal of electronic waste (e-waste) in developing countries is causing an increasing concern due to its effects on the environment and associated human health risks. To understand the contamination status, we measured trace elements (TEs) in soil, air dust, and human hair collected from e-waste recycling sites (a recycling facility and backyard recycling units) and the reference sites in Bangalore and Chennai in India. Concentrations of Cu, Zn, Ag, Cd, In, Sn, Sb, Hg, Pb, and Bi were higher in soil from e-waste recycling sites compared to reference sites. For Cu, Sb, Hg, and Pb in some soils from e-waste sites, the levels exceeded screening values proposed by US Environmental Protection Agency (EPA). Concentrations of Cr, Mn, Co, Cu, In, Sn, Sb, Tl, Pb and Bi in air from the e-waste recycling facility were relatively higher than the levels in Chennai city. High levels of Cu, Mo, Ag, Cd, In, Sb, Tl, and Pb were observed in hair of male workers from e-waste recycling sites. Our results suggest that e-waste recycling and its disposal may lead to the environmental and human contamination by some TEs. To our knowledge, this is the first study on TE contamination at e-waste recycling sites in Bangalore, India.

Contamination by polybrominated diphenyl ethers and persistent organochlorines in catfish and feed from Mekong River Delta, Vietnam

Commercial feeds for aquaculture and catfish samples were collected from the Mekong River Delta, Vietnam, for determination of polybrominated diphenyl ethers (PBDEs) and selected persistent organochlorines, including polychlorinated biphenyls (PCBs), DDT and its metabolites (DDTs), chlordane-related compounds (CHLs), hexachlorocyclohexane isomers (HCHs), and hexachlorobenzene (HCB). The most abundant contaminants were DDTs, with concentrations ranging from 10 to 700 ng/g lipid weight, followed by PCBs (1.0-80 ng/g), CHLs (<0.01-8.2 ng/g), PBDEs (0.12-3.7 ng/g), HCHs (<0.03-5.1 ng/g), and HCB (<0.07-3.2 ng/g). Polybrominated diphenyl ethers were detected in all samples, suggesting their widespread contamination in the region. However, PBDE contamination levels in the present catfish specimens were low in comparison to levels worldwide. Interestingly, residue levels of all the contaminants were significantly higher in catfish collected near a municipal dumping site compared to farmed catfish. This suggests that runoffs from the dumping site during floods and rains may have brought pollutants to the surrounding areas. Contamination pattern in aquaculture feeds revealed elevated levels of PCBs and PBDEs in samples from foreign companies, perhaps implying their higher residues in some imported ingredients. Congener profiles of PBDEs and PCBs demonstrated similarity between the farmed catfish and the aquaculture feeds, suggesting these feeds as a major source of pollution to the farmed catfish. On the other hand, the PBDE and PCB profiles in the dumpsite catfish are clearly different from those of the farmed catfish, revealing their exposure to different sources. Risk assessment showed significantly higher intake of the contaminants by people who eat catfish cultured near the dumping areas. Further investigation regarding fate and occurrence of the contaminants in dumping sites is necessary.

Regional variations in trace element concentrations in tissues of black tiger shrimp Penaeus monodon (Decapoda: Penaeidae) from South Vietnam

The goal of the present study was to examine the specific bioaccumulation of 22 trace elements in muscle, exoskeleton and hepatopancreas of black tiger shrimp Penaeus monodon from the Mekong River Delta (MRD), and the South Key Economic Zone (SKEZ), South Vietnam. The general tendency in most trace element concentrations among different tissues were hepatopancreas>exoskeleton>muscle. Comparisons of trace element levels in tissues between the two regions showed that concentrations of Se in muscle and As in all three tissues were higher in SKEZ; whereas in MRD, the higher concentrations of most elements such as Mn, Cu, Cd, Ba, Hg, were observed in tissues. These geographical variations in trace element levels may reflect the differences in human activities between the two regions of South Vietnam. The target hazard quotient (THQ) values for trace elements (<1) indicate that local residents are not exposed to potential health risks via the consumption of shrimp.

Exposure, metabolism, and health effects of arsenic in residents from arsenic-contaminated groundwater areas of Vietnam and Cambodia: a review.

In this review, we summarize the current knowledge on exposure, metabolism, and health effects of arsenic (As) in residents from As-contaminated groundwater areas of Vietnam and Cambodia based on our findings from 2000 and other studies. The health effects of As in humans include severe gastrointestinal disorders, hepatic and renal failure, cardiovascular disturbances, skin pigmentation, hyperkeratosis, and cancers in the lung, bladder, liver, kidney, and skin. Arsenic contamination in groundwater is widely present at Vietnam and Cambodia and the highest As levels are frequently found in groundwater from Cambodia. Sand filter system can reduce As concentration in raw groundwater. The results of hair and urine analyses indicate that residents from these As-contaminated areas are exposed to As. In general, sex, age, body mass index, and As exposure level are significantly associated with As metabolism. Genetic polymorphisms in arsenic (+III) methyltransferase and glutathione-S-transferase isoforms may be influenced As metabolism and accumulation in a Vietnamese population. It is suggested oxidative DNA damage is caused by exposure to As in groundwater from residents in Cambodia. An epidemiologic study on an association of As exposure with human health effects is required in these areas.

Bioaccumulation and distribution of trace elements in tissues of giant river prawn Macrobrachium rosenbergii (Decapoda: Palaemonidae) from South Vietnam

Accumulation profiles of 22 trace elements in abdominal muscle, abdominal exoskeleton and the hepatopancreas of the giant river prawn Macrobrachium rosenbergii were analyzed. The giant river prawn is an indigenous freshwater species from South Vietnam, and is cultured commercially and fished in the wild. Samples were collected from Ho Chi Minh City and the surrounding area (SKEZ, South Key Economic Zone), and from the Mekong River Delta between 2003 and 2005. Highest accumulations of essential (Cu, Se and Mo) and toxic (As, Ag, Cd and Hg) elements were observed in hepatopancreatic tissue, except for Mn, Sr, Sn, Ba and V in the exoskeleton and Rb and Cs in muscle tissue. Spatial differences showed concentrations of Cs and Pb in muscle and Sr in exoskeletons from the SKEZ were higher than those from the Mekong River Delta. The opposite trend was observed for Cr, Se and Sb in muscle, Mo, Sb and TI in exoskeleton, and Se, Hg, Mo, Cd, Sb, TI and Bi in the hepatopancreas. These differences in trace element concentrations in prawns likely reflect differences in industrialization and human activities between the two regions of South Vietnam.

Stable isotope-guided analysis of biomagnification profiles of arsenic species in a tropical mangrove ecosystem.

We performed stable carbon and nitrogen-guided analyses of biomagnification profiles of arsenic (As) species, including total As, lipid-soluble As, eight water-soluble As compounds (arsenobetaine (AB), arsenocholine (AC), tetramethylarsonium ion (TETRA), trimethylarsine oxide (TMAO), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA), arsenate (As[V]), and arsenite (As[III])), and non-extracted As in a tropical mangrove ecosystem in the Ba Ria Vung Tau, South Vietnam. Arsenobetaine was the predominant As species (65-96% of water-soluble As). Simple linear regression slopes of log-transformed concentrations of total As, As fractions or individual As compounds on stable nitrogen isotopic ratio (δ15N) values are regarded as indices of biomagnification. In this ecosystem, lipid-soluble As (slope, 0.130) and AB (slope, 0.108) were significantly biomagnified through the food web; total As and other water-soluble As compounds were not. To our knowledge, this is one of the first reports on biomagnification profiles of As compounds from a tropical mangrove ecosystem.

Human exposure to arsenic from groundwater in the Red River and Mekong River Deltas in Vietnam

Groundwater contamination by arsenic is a serious environmental problem in the world. Yet there have been few studies conducted in Southeast Asian countries. This article surveys arsenic contamination in groundwater and residents from Vietnam, and is based on our previous studies. Samples of groundwater (n = 118), human hair (n = 59), and urine (n = 100) were collected in the Red River and Mekong River Deltas during 2001–2004. Arsenic was detected in most of the groundwater samples, and its level ranged from <0.1 to 486 µg/l. Elevated concentrations of arsenic were observed in groundwater at some locations in Ha Nam (up to 486 µg/l) in the Red River Delta and Dong Thap (up to 411 µg/l) in the Mekong River Delta. Remarkably, about 33% of these groundwater samples exceeded the WHO drinking water guideline of 10 µg/l. These results suggest that arsenic contamination in groundwater may be widely present in both the Red River and Mekong River Deltas, Vietnam. A significant positive correlation was observed between arsenic concentrations in groundwater and human hair. Arsenic speciation of human urine revealed the presence of inorganic arsenic, and these concentrations positively correlated with arsenic levels in groundwater. Thus, it is likely that residents in our study areas are chronically exposed to arsenic through drinking groundwater, suggesting that there is a health risk from arsenic in Vietnam.

Concentrations of trace elements in Meretrix spp. (Mollusca: Bivalva) along the coasts of Vietnam

The dominant coastal bivalve in Vietnam, hard clams Meretrix spp., collected from the South Key Economic Zone (SKEZ), the Mekong River Delta, and the Central Coastal Zone (CCZ) were analyzed for 21 trace elements. Comparison of the results from the three regions indicated that levels of most of the trace elements, especially As, Mo, Sn, and Pb, were highest in the samples collected from the CCZ, whereas most of the trace elements were found to be present at relatively low levels in samples from the SKEZ. The high concentrations of these trace elements in the CCZ, a sparsely populated region with less human activity than the other two regions, were believed to have originated from industrial waste produced in a shipyard. Although the trace element concentrations in the bivalves were within safe levels for human-consumption criteria reported by the United State Food and Drug Administration and the European Commission, estimation of cancer risk based on As concentration indicates that the hard clams from the CCZ pose a high risk to consumers. Thus, the industrial waste produced in the less densely populated region might increase the health risk to consumers via the contamination of bivalves commonly used as food.

Polychlorinated biphenyl (PCB) concentrations and congener composition in masu salmon from Japan: A study of all 209 PCB congeners by high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS)

We collected two subspecies of masu salmon: Oncorhynchus masou masou from four localities (southern Sea of Japan northward to Hokkaido) and O. masou ishikawae from upstream from Ise Bay close to a heavy industrial area. All 209 PCB congeners were analyzed using HRGC/HRMS. PCA ordination of congener concentrations divided data into three groups: (i) ssp. masou from Hokkaido, (ii) ssp. masou from the other regions and (iii) ssp. ishikawae. The highest ∑ PCB concentration (40.39 ng/wet wt) was in ssp. ishikawae followed by ssp. masou from southern waters; however the TEQdioxin-like PCBs was highest in ssp. masou from southern water (1.96 pg-TEQdioxin-like PCBs/g wet wt.) due to the high proportion of congener #126 in its complement (#126 has the highest toxic equivalency factor among congeners). There is likely a contamination source offshore in the southern Sea of Japan and/or along the migratory route of ssp. masou.

Trace element concentrations in barramundi (Lates calcarifer) collected along the coast of Vietnam

We determined concentrations of 23 trace elements (TEs), and stable carbon and nitrogen isotope (δ(13)C and δ(15)N) signatures in barramundi (Lates calcarifer) specimens collected along the coast of Vietnam in the Northern (NCZ), Central (CCZ) and Southern (SCZ) zones in the period 2007-2010. A combination of δ(13)C and δ(15)N signatures provided insight into ontogenetic shifts in barramundi foraging choices. There were clear zone-dependent differences in Mn, As, Sr and Tl concentrations; levels of Tl were highest in the NCZ, As in the CCZ, and Mn and Sr in the SCZ. Lowest concentrations of Rb occurred in the NCZ, Bi was lowest in the CCZ, and Cd and Cs were lowest in the SCZ. δ(15)N values significantly increased with increasing Zn, Se, Sn and Cs. Concentrations of TEs in barramundi from Vietnam were below worldwide guidelines for human consumption.