Polycyclic aromatic hydrocarbons in three commercially available fish species from the Bonny and Cross River estuaries in the Niger Delta, Nigeria

The concentrations and compositional patterns of the USEPA 16 polycyclic aromatic hydrocarbons were investigated in three commercially available fish species, Chrysichthys nigrodigitatus, Cynoglossus senegalensis and Polydactylus quadratifilis, from the Bonny and Cross River systems in the eastern Niger Delta of Nigeria. The objective of the study was to provide useful information on the levels and sources of polycyclic aromatic hydrocarbons (PAHs) and the associated risks with their consumption. The 16 PAHs in the fish samples were extracted by ultrasonication with hexane/dichloromethane, and the concentrations of PAHs in the extracts were quantified by gas chromatography-mass spectrometry. The measured concentrations of the Ʃ16 PAHs in Chrysichthys nigrodigitatus, Polydactylus quadratifilis and Cynoglossus senegalensis ranged from 106 to 491, from 43.1 to 1734 and from 96.4 to 937 μg kg(-1) in the Bonny River system and from 20.0 to 975, from 24.7 to 506 and from 24.9 to 387 μg kg(-1) in the Cross River system, respectively. The compositional patterns of the PAHs showed that the three- and four-ringed PAHs were the major contributors to the PAH burden in these fish species. The diagnostic ratios indicate that the PAHs in these fish samples originated mainly from combustion processes. The health risk assessment, as determined from the benzo[a]pyrene potency equivalent factor, margin of exposure and incremental lifetime cancer risk, indicates that PAHs in the majority of these fish species can induce potential carcinogenic effects.

Concentrations and exposure risks of some metals in facial cosmetics in Nigeria

The concentrations of nine metals (Cd, Pb, Ni, Cr, Co, Cu, Fe, Mn and Zn) were determined in lip sticks, lip glosses, lip balms, eye pencils, eyeliners, eye shadows, blushes, mascaras and face powders. The study was aimed at providing information on the risk associated with human exposure to metals in these facial cosmetic products. The concentrations of metals in the samples were measured by atomic absorption spectrometry after digestion with a mixture of nitric acid, hydrochloric acid and hydrogen peroxide. The mean concentrations of metals in these facial cosmetics ranged from 3.1 to 8.4 μg g^-1 Cd, 12-240 μg g^-1 Pb, 9.1-44 μg g^-1 Cr, 18-288 μg g^-1 Ni, 1.6-80 μg g^-1 Cu, 7.9-17 μg g^-1 Co, 2.3-28 mg g^-1 Fe, 12-230 μg g^-1 Mn, and from 18 to 320 μg g^-1 Zn. The concentrations of Ni, Cr and Co were above the suggested safe limit of 1 μg g^-1 for skin protection, while Cd and Pb were above the Canadian specified limits. The systemic exposure dosage (SED) values for these metals obtained from the use of these facial cosmetic products were below their respective provisional tolerable daily intake (PTDI)/or recommended daily intake (RDI) values. The margin of safety values obtained were greater than 100 which indicated that the concentrations of the metals investigated in these facial cosmetics do not present considerable risk to the users except in the case of face powders.

Determination and human exposure assessment of polybrominated diphenyl ethers and tetrabromobisphenol A in indoor dust in South Africa

The concentration of TBBPA in dust samples from automobiles (n = 14), computer laboratories (n = 8), homes (n = 7), and offices (n = 7), and, also, PBDE concentrations in the indoor dust of 19 personal and previously owned automobiles in Durban, South Africa, were determined. Gas chromatography coupled with mass spectrometry was applied for the separation, identification, and quantitation of TBBPA and PBDEs. The median concentrations of TBBPA were 1156, 269, 120, and 492 ng g(-1) in automobiles, computer laboratories, homes, and offices, respectively. The ∑ n = 8 PBDE in 19 automobile samples ranged from 573 to 11,833 ng g(-1). BDE-209 accounted for approximately 42% of ∑ n = 8 PBDE in the samples. Household characteristics influenced the distribution of TBBPA in the various microenvironments. By assuming an average dust ingestion rate, and a median TBBPA concentration, the ∑DED (in ng kg(-1) bw day(-1)) of TBBPA is 0.08, 0.08, and 0.60, for an adult, teenager, and toddler, respectively. These doses are similar to dust ingestion intakes reported for Asian countries where there is a high demand for TBBPA as a flame retardant. Similarly, automobiles provide ample opportunity for human exposure to PBDEs via dust ingestion, particularly for toddlers and occupationally exposed adults.

A combined TD-DFT and spectroscopic investigation of the solute-solvent interactions of efavirenz

Efavirenz, commercially known as Sustiva® or Stocrin®, is a first-line antiretroviral treatment for HIV/AIDS. The clinical efficacy of efavirenz is, however, hindered by its solubility. We sought to investigate the solute-solvent effects of efavirenz by means of a combined qualitative study implementing UV-visible spectrophotometry, (1)H NMR spectroscopy and time-dependent density functional theory (TD-DFT) calculations. The UV spectrum displayed two main absorbance maxima, band I and band II at 246-260 and 291-295 nm, respectively. A general bathochromic shift was noticed from the non-polar solvent cyclohexane to the most polar solvent DMSO (≈13.69 nm) in band I and a smaller bathochromic (≈2.17 nm) and hyperchromic shift was observed in band II. We propose that these observations are due to the role of the amino (NH) and carbonyl (CO) functionalities which induce charge-transfer and intra- and inter-molecular hydrogen bonding. The aromatic and amine protons showed the most deshielded effects in the observed chemical shifts (δ) in the more polar DMSO-d6 solvent relative to CDCl3. The (1)H NMR chemical shifts observed are due to the increased delocalization of the lone pair electrons of the amino nitrogen with increased polarity of the more polar DMSO solvent. The theoretical reproduction of the UV and (1)H NMR spectra by means of TD-DFT is in good agreement with the experimental results.

Nitrogen-functionalised carbon nanotubes as a novel adsorbent for the removal of Cu(ii) from aqueous solution

Nitrogen-functionalized multiwalled carbon nanotubes synthesized were effective and efficient for the removal of Cu²⁺ from aqueous solutions.

Safety Evaluation of Metal Exposure From Commonly Used Hair Dyes and Tattoo Inks in Nigeria

In the study described in this article, the concentrations of metals (cadmium, copper, chromium, aluminum, lead, nickel, zinc, cobalt, manganese, and iron) in samples of some commonly used hair dyes and tattoo inks were determined with a view to providing information on the hazards associated with the use of these products. The concentrations of metals were measured after nitric acid/perchloric acid/hydrogen peroxide digestion by atomic absorption spectrometry. Results indicated that the tattoo ink samples contained allergenic metals such as nickel, chromium, and cobalt at concentrations above the suggested limit of 1 μg/g for greater skin protection, and the toxic metals were below their respective prescribed limits, as impurities in ingredients for use for cosmetics, in the majority of the samples.

Polybrominated diphenyl ethers and polychlorinated biphenyls in indoor dust in Durban, South Africa

Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) were measured in indoor dust of three microenvironments in Durban, South Africa. The sum of eight PBDEs and three PCBs were quantified by gas chromatography with mass spectral detection. The mean concentrations of ∑n = 8 PBDEs and ∑n = 3 PCBs in 10 homes, 11 offices, and 13 university students' computer laboratories were 1710, 1520, and 818 ng/g, and 891, 923, and 1880 ng/g for PBDEs and PCBs, respectively. The concentration of PCBs found in homes was independent (P = 0.0625) of building construction year. Similarly, no relationship was observed between PCB concentrations and floor type. The concentrations of PBDEs correlated (r = 0.60) with PCB concentrations in homes, thus assuming similar sources. The elevated concentrations of PBDEs and PCBs may have significant implications for human exposure.

An assessment of polybrominated diphenyl ethers and polychlorinated biphenyls in the indoor dust of e-waste recycling facilities in South Africa: implications for occupational exposure

Workplace exposure to persistent organic pollutants is a concern for human health. This study examined the presence of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in the indoor dust from two major e-waste recycling sites and a university electronic equipment repair workshop in Durban, South Africa, in order to evaluate the implication of dust for occupational exposure. The mean ∑(n = 8)PBDEs and ∑(n = 3)PCBs were 20,094 and 235 ng g(-1), respectively. The levels of PBDEs and PCBs obtained in one of the recycling sites (123-27,530 and 161-593 ng g(-1)) were significantly higher than the levels obtained (91-7686 and <DL-42 ng g(-1), respectively) in the same site after site cleanup/maintenance. Occupational exposure was assessed for different exposure scenarios by using the 5th and 95th percentile, and the median and mean concentrations measured at the sites. By assuming a mean and a high dust intake rate, the average and 95th percentile daily exposure doses (∑DED/ng kg(-1) bw day(-1)) of PBDEs were 3.98, 8.52 and 7.58, 16.19, respectively, and of PCBs were 0.047, 0.094 and 0.089, 0.179, respectively. The ∑DEDs of PBDEs and PCBs were lower than the reference (RfD) values for BDE 47, BDE 99, BDE 153 and BDE 209, and Aroclor 1254 and 1016. Nevertheless, continual exposure to high levels of these pollutants is a concern; but as shown, the exposure can be significantly reduced if the e-waste facilities are cleaned thoroughly regularly.

Concentrations and profiles of polycyclic aromatic hydrocarbons in some popular fish species in Nigeria

The concentrations and profiles of polycyclic aromatic hydrocarbons (PAHs) in 10 popular fish species in the Nigerian market were determined with a view to providing information on the health hazards associated with the consumption of these fish species. The concentrations of PAHs were measured by gas chromatography-mass spectrometry after extraction by ultrasonication with acetone-dichloromethane and clean up. The concentration ranges of the Σ16 PAHs were 20 to 39.6 μg kg(-1) for Parachanna obscura (African snake head), 6.8 to 532.3 μg kg(-1) for Oreochromis niloticus (tilapia), 7.4 to 91.1 μg kg(-1) for Gymnarchus niloticus (Asa), 13.1 to 34.1 μg kg(-1) for Sebastes fasciatus (red fish), 11.2 to 80.0 μg kg(-1) for Gadus morhua (cod), 23.9 to 34.6 μg kg(-1) for Chrysicthys nigrodigitatus (silver cat fish), 63.4 to 131.4 μg kg(-1) for Sardinella aurita (sardine), 22 to 52.9 μg kg(-1) for Trachurus trachurus (Atlantic horse mackerel), 21.0 to 63.7 μg kg(-1) for Scomber scombrus (mackerel), and 27.7 to 44.5 μg kg(-1) for Pseudotolithus senegalensis (croaker). Benzo[a]pyrene occurred in 23% of these fish samples at concentrations above the European Union permissible limit of 2.0 μg kg(-1). The calculated margins of exposure based on the indicators for occurrence and effects of PAHs were greater than 10,000 indicating no potential risk for the consumers of the species evaluated in this study.

Effectiveness of carbon nanotube–cobalt ferrite nanocomposites for the adsorption of rhodamine B from aqueous solutions

Magnetic cobalt ferrite–carbon nanotube nanocomposites are effective and reusable adsorbents for remediation of wastewaters contaminated with dyes.

Oxyhalogen–Sulfur Chemistry: Oxidation of a Thiourea Dimer, Formamidine Disulfide, by Chlorine Dioxide

The oxidation of formamidine disulfide, FDS, the dimer of thiourea, by aqueous chlorine dioxide has been studied in highly acidic and mildly acidic media. FDS is one of the possible oxidation intermediates formed in the oxidation of thiourea by oxyhalogens to urea and sulfate. The reaction is exceedingly slow, giving urea and sulfate with a stoichiometric ratio of 5 : 14 FDS to chlorine dioxide after an incubation period of up to 72 h and only in highly acidic media which discourages the disproportionation of chlorine dioxide to the oxidatively inert chlorate. Mass spectrometric data suggest that the oxidative pathway proceeds predominantly through the sulfinic acid, proceeding next to the products sulfate and urea, while by-passing the sulfonic acid. Transient formation of the unstable sulfenic acid was also not observed.

Detailed mechanistic investigation into the S-nitrosation of cysteamine

The nitrosation of cysteamine (H₂NCH₂CH₂SH) to produce cysteamine-S-nitrosothiol (CANO) was studied in slightly acidic medium by using nitrous acid prepared in situ. The stoichiometry of the reaction was H₂NCH₂CH₂SH + HNO₂ → H₂NCH₂CH₂SNO + H₂O. On prolonged standing, the nitrosothiol decomposed quantitatively to yield the disulfide, cystamine: 2H₂NCH₂CH₂SNO → H₂NCH₂CH₂S-SCH₂CH₂NH₂ + 2NO. NO₂ and N₂O₃ are not the primary nitrosating agents, since their precursor (NO) was not detected during the nitrosation process. The reaction is first order in nitrous acid, thus implicating it as the major nitrosating agent in mildly acidic pH conditions. Acid catalyzes nitrosation after nitrous acid has saturated, implicating the protonated nitrous acid species, the nitrosonium cation (NO⁺) as a contributing nitrosating species in highly acidic environments. The acid catalysis at constant nitrous acid concentrations suggests that the nitrosonium cation nitrosates at a much higher rate than nitrous acid. Bimolecular rate constants for the nitrosation of cysteamine by nitrous acid and by the nitrosonium cation were deduced to be 17.9 ± 1.5 (mol/L)^-1 s^-1 and 6.7 × 10⁴ (mol/L)^-1 s^-1, respectively. Both Cu(I) and Cu(II) ions were effective catalysts for the formation and decomposition of the cysteamine nitrosothiol. Cu(II) ions could catalyze the nitrosation of cysteamine in neutral conditions, whereas Cu(I) could only catalyze in acidic conditions. Transnitrosation kinetics of CANO with glutathione showed the formation of cystamine and the mixed disulfide with no formation of oxidized glutathione (GSSG). The nitrosation reaction was satisfactorily simulated by a simple reaction scheme involving eight reactions.

Redetermination of chlorido(2,2′:6′,2′′-terpyridine-κ3 N,N′,N′′)gold(I) dichloride trihydrate at 173 K. Corrigendum

Corrigendum to Acta Cryst. (2008), E64, m1240.

The title of the paper by Friedrich, Maguire, Martincigh, McKay & Pietersen [Acta Cryst. (2008), E64, m1240] is corrected.

Redetermination of chlorido(2,2':6',2''-terpyridine-κN,N',N'')gold(I) dichloride trihydrate at 173 K

The redetermined structure of the title compound, [AuCl(C(15)H(11)N(3))]Cl(2)·3H(2)O, at 173 (2) K is reported. The structure displays O-H⋯Cl and O-H⋯O hydrogen bonding. The distance of one of the chloride ions from the gold(I) atom [5.047 (1) Å] differs from that determined previously.

Ultraviolet protective performance of photoprotective lipsticks: change of spectral transmittance because of ultraviolet exposure

BACKGROUND

Photoinstability of sunscreens because of ultraviolet (UV) exposure is a well-known and common phenomenon. Recently, it was also shown that sunscreens with complex filter combinations are photoinactivated by UV exposures, which can easily be acquired by solar exposure over several hours.

OBJECTIVES

To assess the change of the spectral transmission after UV exposure (UV-challenged protective performance) of 27 commercially available photoprotective lipsticks.

METHODS

Quartz slides were covered with a lipstick layer (area density 1.0+/-0.1 mg/cm2) and irradiated with increasing doses of solar-simulated radiation. The spectral transmission (T) was measured spectrophotometrically before and after 5, 12.5, 25, and 50 standard erythema doses (SED) of exposure. We calculated the change in transmission (photoinstability) as the difference between the spectral transmission before and after a defined UV exposure, DeltaT, and the arithmetic mean, for both the UVA (DeltaTA) and UVB (DeltaTB) ranges. A product was labelled as photounstable if the mean photoinstability in the UVA, DeltaTA, or UVB range, DeltaTB, was higher than 5% for an UV exposure of 12.5 SED.

RESULTS

Eleven products showed a significant photoinstability in the UVA range (DeltaTA between 6% and 27%), only one product in the UVB range (DeltaTB = 13%), and one product in both the UVA (DeltaTA = 31%) and UVB (DeltaTB = 9%) range. In one product photoinstability became significant in the UVA range at higher UV exposures.

CONCLUSIONS

Out of 27 lipsticks only 13 products showed a photostable performance (DeltaTA < 5% and DeltaTB < 5% for 12.5 SED). We propose therefore that only products, which fulfil these UV photostability criteria should be marketed.