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PubMed2003

Determination of organochlorine pesticides in water using microwave assisted headspace solid-phase microextraction and gas chromatography.

A coupled technique, microwave-assisted headspace solid-phase microextraction (MA-HS-SPME), was investigated for one-step in situ sample pretreatment for organochlorine pesticides (OCPs) prior to gas chromatographic determination. The OCPs, aldrin, o,p'-DDE, p,p'-DDE, o,p'-DDT, p,p'-DDT, dieldrin, alpha-endosulfan, beta-endosulfan, endosulfan sulfate, endrin, delta-HCH, gamma-HCH, heptachlor, heptachlor epoxide, methoxychlor and trifluralin were collected by the proposed method and analyzed by gas chromatography with electron-capture detection (GC-ECD). To perform the MA-HS-SPME, six types of SPME fibers were examined and compared. The parameters affecting the efficiency in MA-HS-SPME process such as sampling time and temperature, microwave irradiation power, desorption temperature and time were studied to obtain the optimal conditions. The method was developed using spiked water samples such as field water and with 0.05% humic acid in a concentration range of 0.05-2.5 microg/l except endosulfan sulfate in 0.25-2.5 microg/l. The detection was linear over the studied concentration range with r2>0.9978. The detection limits varied from 0.002 to 0.070 microg/l based on S/N=3 and the relative standard deviations for repeatability were <15%. A certified reference sample of OCPs in aqueous solution was analyzed by the proposed method and compared with the conventional liquid-liquid extraction procedure. These results are in good agreement. The results indicate that the proposed method provides a very simple, fast, and solvent-free procedure to achieve sample pretreatment prior to the trace-level screening determination of organochloride pesticides by gas chromatography.

Chromatography, Gas↗
PubMed2001

PCBs and organochlorine pesticide residues in eggs of Audouin's gull (Larus audouinii) in the north-eastern Mediterranean.

Levels of eight PCB congeners (IUPAC 8, 20, 28, 52, 101, 118, 138, 180) and 13 organochlorine pesticides (alpha-BHC, beta-BHC, lindane (gamma-BHC), heptachlor, heptachlor epoxide, aldrin, dieldrin, endrin, 2,4'-DDT, 2,4'-DDD, 4,4'-DDT, 4,4'-DDD, 4,4'-DDE) were measured in unhatched Audouin gull eggs from Aegean Sea (northeastern Mediterranean) colonies in 1997 and 1998. Levels of more persistent congeners 138, 180 and in some colonies 118, predominated among PCBs. Between years significant differences were found in the levels of a variety of contaminants in the same regional colonies (Lipsos, Agathonisi, and Fourni) attributable to temporal changes in diet. Within years differences were limited (1997: PCB congeners 52, 118, 180, heptachlor and 4,4'-DDD; 1998: PCB congener 8 and heptachlor epoxide) which in combination with cluster analysis suggest a temporal rather than spatial pattern of pollution in the Aegean Sea. Maximum median levels of five PCB congeners, total PCBs and eight organochlorine pesticides were found in the Agathonisi and Fourni colonies suggesting an elevated nearby pollution probably from the polluted Menderez River. Levels of all contaminants were too low to have any adverse reproductive effects on the Audouin's gull of the Aegean colonies.

Animals↗
PubMed2002

Organochlorine pesticides and PCB residues in sediments of Alexandria Harbour, Egypt.

Persistent organochlorine compound concentrations were determined for 23 surface sediment samples collected from Alexandria Harbor, Egypt. Total PCB concentrations ranged from 0.9 to 1210 ng/g with four to seven Cl-substituted biphenyls being the most prevalent PCBs congeners. Different PCB congener distribution patterns were observed, probably reflecting different inputs and attenuation at various locations. Total DDT concentrations varied from <0.25 ng/g to 885 ng/g. The ratios of DDTs (2,4'- and 4,4'-DDT)/total DDTs (DDTs plus metabolites) in sediment samples from certain sites were 0.86 or higher, indicating little attenuation or recent input of DDT. Total chlordane (the sum of heptachlor and its epoxide, oxy-, gamma- and alpha-chlordane and cis + trans-nonachlor) ranged from <0.25 to 44 ng/g with the highest concentration found in the Arsenal Basin. The geographic distributions of PCBs, total DDTs and total chlordane were similar. Chlorinated benzenes (CBs), hexachlorocyclohexanes (HCHs), aldrin, dieldrin, endrin, chloropyrifos, endosulfan, mirex and pentachloroanisole were below detection limits or detected at low concentrations in most of the samples. Sites that were contaminated with high concentrations of organochlorine compounds were associated with dense population and low energy environment. The contamination levels of PCBs, total DDTs and total chlordane were in high range compared to other locations worldwide.

Egypt↗
PubMed2001

Monitoring of organochlorine and organophosphorus pesticides in the water of the Reconquista River (Buenos Aires, Argentina).

The Reconquista river is a typical example of the adverse impact of human activity on a watercourse. Approximately 10% of the population of the country is settled on its basin and it receives wastewater discharges from residences and industries. This paper describes the results of the first systematic data for measurement of pesticides in surface water of the river, based on a monthly monitoring program over two-year span. The analyses were performed, in three sampling stations (S1, S2 and S3), along 46 km of its course, following the AOAC methods. Screening included the following pesticides: (a) Organochlorines: alpha, beta and gamma HCH; heptachlor, heptachlor epoxide; aldrin; endrin; dieldrin; op' and pp' DDT; op' and pp' DDE; alpha and gamma chlordane and endosulphan II; (b) Organophosphates: ethyl and methyl parathion; chlorpyrifos and fenitrothion. From the 60 samples analyzed, 35% contained organochlorine pesticides in a concentration higher than the detection limit. Organophosphates were found in no case. Throughout the studied period, DDT and its metabolite DDE were only found in S1 and gamma chlordane in S3; heptachlor was present in 50% of the samples of S2 and in 35% of S3, while HCH isomers were detected in 38% of S2 and 45% of S3 samples. Neither temporal nor spatial trends were found. There was not a relationship between the time of samplings and the fumigation season for farming purposes. At all locations, pesticides levels were found to be between 40 and 400 times higher than the legal limits established for protection of aquatic life.

Agriculture↗
PubMed2003

Comparison of nutrient and contaminant fluxes in two areas with different hydrological regimes (Empordà Wetlands, NE Spain).

Nutrient (N and P), heavy metal (Ni, Cd, Cr, Cu and Pb) and pesticide (DDT, DDD, DDE, lindane, aldrin, endrin, dieldrin, permethrin, atrazine and simazine) concentrations in water and sediment were analysed in the Empordà Wetlands, a Mediterranean wetland area in NE Spain. Mean nutrient and contaminant concentrations and input and output loads via tributaries were compared in two marshes with different water turnover: a freshwater marsh (FWM), with a high water turnover rate due to continuous surface water inputs and outputs, and a brackish water marsh (BWM), with lower turnover and no continuous surface output, where water remains confined during dry periods. Mean concentrations of most heavy metals exceeded the maximum permissible concentration (MPC) in BWM, whilst only some pesticides reached MPC in FWM. The confined waters of BWM showed higher sensitivity to contaminant input loadings than FWM due to the lack of continuous water outputs. Non-point source pollution inputs during runoff (mainly in FWM) and concentration during confinement (mainly in BWM) showed as the main environmental problems related to nutrients and contaminants in these ecosystems. Thus, the importance of confinement and its effect on pollutant concentrations must be borne in mind to achieve correct management of Mediterranean wetlands.

Ecosystem↗
PubMed2002

Contamination by selected chlorinated pesticides in surface waters in Hanoi, Vietnam.

Fifteen insecticides, which were banned in Vietnam in the period from 1990 to 1998, were chosen for the investigation of surface water samples in Hanoi and its surroundings. The investigation was focused on an area of approximately 30 by 20 km. Thirty water samples, in total were analysed: 11 samples from the Red river, seven from the Duong river, four from various lakes (West lake, Thuyen Quang, Bay Mau, Ba Mau), six from irrigation canals and two samples from wells. The procedure was repeated in November 1998 and in August 1999. The results showed that the contamination of the banned pesticides was highest in the rivers and then in the irrigation canals, followed by the lakes and wells. These pesticides could hardly be determined in just two drinking water samples (wells) and their concentrations rarely exceeded detection limits (0.05-0.25 ng l(-1)). The mean concentrations of sigmaHCHs (alpha, beta, gamma, delta-HCH) and sigmaDDTs (2,4'-, 4,4'-DDE; 2,4'-, 4,4'-DDD; 2,4'-, 4,4'-DDT) in the rivers were 17.2 +/- 71.8 and 43.7 +/- 79.9 ng l(-1) in the dry season (DS, November 1998), 29.3 +/- 117 and 56.1 +/- 65.6 ng l(-1) in the rainy season (RS, August 1999), respectively. However, the highest concentration of DDTs detected in a river sample (DS): 0.324 microg l(-1) was much lower than their allowable limit of concentration in surface waters, which is accorded with Criteria of Vietnam (1995) (DDTs < 10 microg l(-1)). Moreover, endrin, heptachlor, aldrin were also detected in most of water samples with considerable mean concentrations in rivers: 25.3 +/- 40.5, 17.4 +/- 23.8, 11.0 +/- 9.02 ng l(-1) in the DS and 18.5 +/- 23.2, 19.3 +/- 29.0, 12.8 +/- 8.44 ng l(-1) in the RS, respectively. Heptachlor epoxide (isomer A) and dieldrin were detected in some water samples with lowest concentrations.

Environmental Monitoring↗
PubMed2002

Distribution and fate of organochlorine pesticide residues in sediments from the selected rivers in Taiwan.

The contamination of organochlorine pesticides (OCPs) in sediments from selected rivers in Taiwan was investigated to evaluate the pollution potentials and hazard in river sediments. Da-han River and Erh-jen River were selected as the target rivers due to their serious pollution. A total of 40 surface sediment samples were collected at five sampling stations along the rivers. Results showed that the concentrations of various pesticides in sediments were in the range of 0.57-14.1 ng/g for sigmaHCH, 0.05-0.15 ng/g for aldrin, 0.12-5.8 ng/g for dieldrin, 0.22-0.64 for endrin, 0.24-6.37 ng/g for endosulfan and 0.21-8.81 ng/g for EDDT (p,p'-DDD, p,p'-DDE, p,p'-DDT). Among the OCPs, sigmaHCH, endosulfan and sigmaDDT were the most dominant compounds in the river sediments. Endosulfan sulfate was the most frequent detected compound in the sediments from the selected rivers. Also, sigmaDDT, dieldrin and beta-HCH were in abundance. Different contamination patterns between the selected river sediments were also observed. Da-han River was mainly contaminated with endosulfan sulfate and sigmaDDT. Whereas the main pesticides in Erh-jen River were beta-HCH and sigmaDDT. Among the cyclodiene compounds, dieldrin was in abundance in most of the sediments. Moreover, the frequencies of detection of the metabolites were higher than those of parent compounds, depicting that the sediments have contaminated for a long time. The results obtained in this study showed that there still exist a variety of OCP residues in the river sediments in Taiwan.

Environmental Monitoring↗
PubMed2003

Frozen mitochondria as rapid water quality bioassay.

A rapid and relatively low cost bioassay, usable in routine screening water test has been developed modifying the beef heart mitochondria test. In our experiments, mitochondria (FM22) were frozen at -22 degrees C, instead of -80 degrees C (FM80), and their applicability and sensitivity was verified. The oxygen consumption was measured by a Clark electrode that was interfaced to a PC to collect test analysis data. Blank tests were carried out to verify the oxygen consumption linear fitting. Toxicity tests were performed using pure organic and inorganic compounds, such to verify the FM22 sensitivity. A piecewise regression, through an Excel Macro, identified the break-point in the oxygen consumption and calculated the toxicity. The IC50s of the tested compounds were calculated and ranged from 0.123 to 0.173 mg/l for heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) and from 0.572 to 10.545 mg/l for organics (benzene, DMSO, DDE, endrin, dichloromethane, chlorobenzene, 1,2-dichlorobenzene and 1,3-dichlorobenzene). Water effluent samples were then tested. The FM22 gave different toxic reactions to them. Water samples were characterised for heavy metals. The FM22 bioassay had a higher sensitivity than the FM80 and a high reproducibility in the toxicity test with pure compounds. The FM22 test was a good predictor of toxicity for water samples; the bioassay is easy, low cost and rapid, then usable for routine tests.

Animals↗
PubMed1999

Storage of organochlorine pesticides in human adipose tissues of Jordanian males and females.

Adipose tissue of 50 human patients (5-96, years old) were taken and analysed by gas chromatography equipped with electron capture detector (63Ni) for determination of storage levels of HCH's (alpha, beta, and gamma-hexachlorcyclohexanes), DDT and its metabolites DDE and DDD, the cyclodiens (heptachlor, heptachlorepoxide, dieldrin, aldrin and endrin) and HCB (hexachlorbenzene). The data is reported according to age groups and sexes. The results show relatively moderate concentrations of all studied pesticides and that Jordanian men are more exposed to DDT and HCH's than women.

Adipose Tissue↗
PubMed2000

The incidence of polychlorinated biphenyl and organochlorine pesticide residues in the eggs of the cormorant (Phalacrocorax carbo sinensis): an evaluation of the situation in four Greek wetlands of international importance.

This study contributed to identifying the current levels of organochlorine pollutants in four Greek wetlands of international importance (the Evros and Axios Deltas, and Kerkini and Prespa Lakes), using the cormorant Phalacrocorax carbo sinensis as a suitable bioindicator in a region where such information is scarce. Residue levels of eight polychlorinated biphenyl (PCB) congeners and 13 organochlorine pesticide (OC) compounds were measured in cormorant eggs. Most PCBs and OCs (except dieldrin and endrin) were found in at least some of the study areas. Median concentrations of five PCBs (IUPAC 8, 20, 52, 138, 180) and of six OCs (alpha-BHC, beta-BHC, lindane, heptachlor, 4,4'-DDE and 4,4'-DDT) differed significantly among the areas. The median totals of the PCBs were highly significant among the areas, being unexpectedly highest in Prespa Lake (68.43 ppb), despite its remoteness, and lowest in Evros Delta samples (12.17 ppb). Aldrin that was found in samples from Evros, Axios and Prespa probably accumulated in wintering grounds. In all of the areas, the relative proportions of alpha-BHC and 2,4'-DDD were the highest of all OCs. Fingerprint and cluster analyses illustrated overall differences in the PCB patterns, being greatest between the deltas than between the lakes, but, inversely, for OCs the differences were smaller in the deltas. Differences were attributed to large variations in the cormorants' diet between areas and different regimes of pollutant management in the two types of wetland. Correlations of pollutants varied considerably among areas and they were more diverse in OCs. The sum of OCs/ sum of PCBs ratio indicates agrochemical pollution in all areas. An important finding was that levels of both pollutant groups were too low to have any biological implications on the cormorants and, additionally, suggest that they have a negligible impact on the environment of the wetlands studied.

Animals↗
PubMed2003

Contaminant exposure and effects in pinnipeds: implications for Steller sea lion declines in Alaska.

After nearly 3 decades of decline, the western stock of Steller sea lions (SSL; Eumetopias jubatus) was listed as an endangered species in 1997. While the cause of the decline in the 1970s and 1980s has been attributed to nutritional stress, recent declines are unexplained and may result from other factors including the presence of environmental contaminants. SSL tissues show accumulation of butyltins, mercury, PCBs, DDTs, chlordanes and hexachlorobenzene. SSL habitats and prey are contaminated with additional chemicals including mirex, endrin, dieldrin, hexachlorocyclohexanes, tetrachlorodibenzo-p-dioxin (TCDD) and related compounds, cadmium and lead. In addition, many SSL haulouts and rookeries are located near other hazards including radioactivity, solvents, ordnance and chemical weapon dumps. PCB and DDT concentrations measured in a few SSL during the 1980s were the highest recorded for any Alaskan pinniped. Some contaminant exposures in SSL appear to be elevated in the Gulf of Alaska and Bering Sea compared to southeast Alaska, but there are insufficient data to evaluate geospatial relationships with any certainty. Based on very limited blubber data, current levels of PCBs may not pose a risk to SSL based on comparison to immunotoxicity tissue benchmarks, but SSL may have been at risk from pre-1990 PCB exposures. While exposure to PCBs and DDTs may be declining, SSL are likely exposed to a multitude of other contaminants that have not been monitored. The impacts of these exposures on SSL remain unknown because causal effects have not been established. Field studies with SSL have been limited in scope and have not yet linked contaminant exposures to adverse animal health or population effects. Several biomarkers may prove useful for monitoring exposure and additional research is needed to evaluate their utility in SSL. We conclude that there are insufficient data to reject the hypothesis that contaminants play a role in the continued decline of SSL, and suggest that a coordinated monitoring program be developed which can be related to key biological, ecological and laboratory toxicity data.

Adipose Tissue↗
PubMed2000

Detection of persistent organic pollutants in the Mississippi Delta using semipermeable membrane devices.

From semipermeable membrane devices (SPMDs) placed in five Mississippi Delta streams in 1996 and 1997, the persistent organic pollutants (POPs) aldrin, chlordane, DCPA, DDT, dieldrin, endrin, heptachlor, mirex, nonachlor, and toxaphene were detected. In addition, the insecticides chlorpyriphos, endosulfan, and hexachlorocyclohexanes were detected. Two low-solubility herbicides not detected commonly in surface water, pendimethalin and trifluralin, were also detected.

Aniline Compounds↗
PubMed1996

Genotoxicity of the Ganges water at Narora (U.P.), India.

Water samples were collected from the river Ganga at Narora (U.P.). High performance liquid chromatography analysis of water samples by the liquid extraction procedure indicated the presence of several pesticides such as DDT, alpha-BHC, aldrin, endrin and dieldrin at concentrations of 1.36, 1.38, 0.95, 0.61 and 0.41 ppb, respectively. The organophosphorus pesticides such as dimethoate and methyl parathion also appear to be present at concentrations of 0.20 and 0.41 ppb, respectively. The XAD water concentrates and liquid-liquid extracted water samples were assayed for mutagenic potential by the Ames Salmonella/microsome test. The test samples exhibited a significant degree of mutagenicity with TA102, TA100 and TA98 strains both in the presence and absence of DNA repair defective mutants, recA, lexA and polA of E. coli was observed as compared to their wild-type counterpart in the presence of XAD water concentrates.

Cell Division↗
PubMed2002

Persistent chlorinated pesticides and polychlorinated biphenyls in selected fish species from Lake Tanganyika, Burundi, Africa.

Concentrations of selected organochlorine pesticides and PCBs in seven fish species (cichlids) from the north end of the Lake Tanganyika, Burundi, Africa were determined. Results were compared to previous work on the Lake Tanganyika and other water bodies and to the European Community maximum residue levels (MRLs) in edible fat. The analytical method included a hot Soxhlet extraction with a mixture of acetone: hexane (1:3, v/v), gravimetrically lipid determination, and a single step clean-up. For PCBs and stable pesticides, the clean-up was done on activated silica gel impregnated with concentrated sulfuric acid, while for non acid-stable pesticides superposed layers of alumina, silica and florisil impregnated with 15% methanolic solution of KOH were successively used. Recoveries of organochlorine pesticides from certified reference material (CRM 430) were ranging from 86% for p,p'-DDT to 107% for endrin, while recoveries from blank fat spiked fortified at three different levels were between 65% for alachlor at the lowest fortification level and 107% for mirex at the highest fortification level. The limits of detection for each analyte were ranging from 0.1 ng/g to 0.5 ng/g fat. All chlorinated pesticides were found in the analyzed species but at low concentrations. Boulengerochromis microlepis contained the highest concentrations of HCHs (288.2 +/- 15.5 ng/g fat) and DDTs (909.1 +/- 42.5 ng/g fat), while the highest PCB levels (166.7 +/- 37.4 ng/g fat for the sum of 12 congeners) were found in Oreochromis niloticus. However, there is no evidence that Lake Tanganyika is more contaminated with pesticides than other African water bodies.

Animals↗
PubMed1998

Residues of chlorinated hydrocarbon insecticides in human milk of Jordanian women.

A total of 411 milk samples were screened for the residues of the following chlorinated hydrocarbon insecticides using chromatographic methods: DDT insecticides (P,P'-DDT, P,P'-DDE, P,P'-DDD, O,P' -DDT); cyclodiene insecticides (aldrin, endrin, dieldrin, heptachlor, heptachlorepoxide, cis-and trans-chlordane); hexachlorocyclohexane (alpha-HCH, gamma-HCH) and hexachlorobenzene (HCB). The milk samples were obtained from lactating women selected randomly from five different geographical regions in Jordan. These regions were North and Middle Jordan Valley, Amman, Irbid and Zarqa. All of the studied insecticides were found to contaminate human milk in Jordan, but with high variations in the concentration and percentage of population occurrence. P,P'-DDE was the predominant contaminant occurring in 80.3% of studied population, followed by P,P'-DDT occurring in 53.5%. The regional results showed that the DDT residues were also the predominant contaminant in all regions and that the North and Middle Jordan Valley regions were the most affected. Infant's age (i.e. lactation period) had a significant inverse relationship with the concentration of insecticides in the milk fat.

Journal Article↗
PubMed2000

Organochlorine and organophosphorus pesticide residues in the Atoya river basin, Chinandega, Nicaragua.

The hydrographic basin of the Atoya river, located in the Department of Chinandega, one of the main cotton producing regions in Nicaragua, is intensively contaminated by pesticides. Samples of river waters and sediments, as well as strategically selected wells have been analyzed to study variations in the concentrations of organochlorine and organophosphorus pesticide residues between the dry season (November-April) and the rainy season (May-June). Generally, higher concentrations of pesticides have been detected in the river waters and sediments in the dry season. DDT, DDD, DDE compounds and toxaphene are the most frequent organochlorine residues found in the water and sediment samples, while endrin, aldrin, dieldrin and lindane are mainly found in the waters of rivers and wells. Organophosphorus compounds were rarely detected. However, residues of ethion, methyl-parathion and ethyl-parathion were found in high concentrations in some river and well water samples. Generally, organochlorine compounds tend to accumulate in the fine grain-size fractions, rich in organic matter, except DDE, which concentrates basically in the coarse grain-size fractions.

Journal Article↗
PubMed2002

Analysis of pesticides and PCB congeners in serum by GC/MS with SPE sample cleanup.

This paper describes a simple procedure for the quantitative analysis of 25 polychlorinated biphenyl congeners (PCB) in serum. They are PCB 70, 74, 77, 87, 99, 101, 118, 126, 128, 138, 151, 153, 156, 169, 170, 180, 183, 187, 191, 194, 205, 206, 208 and 209. In addition, 15 pesticides are analyzed in the same extract: aldrin, p,p'-DDE, p,p'-DDT, dieldrin, endrin, endosulfan I, heptachlor, hexachlorobenzene, alpha-hexachlorocyclohexane, beta-hexachlorocyclohexane, lindane, methoxychlor, mirex, pentachlorobenzene, and 1,2,3,4-tetrachlorobenzene. The procedure involved sample cleanup using a combination of C18 and NH(2) solid phase extraction cartridges. The instrumental technique was gas chromatography/mass spectrometry with both electron ionization and negative chemical ionization in the selected ion monitoring mode. Concentration of sub-ng/ml level was attainable with 2 ml of serum sample.

Environmental Monitoring↗
PubMed1997

Comparative in vitro and in vivo protein kinase C activation by selected pesticides and transition metal salts.

Various pesticides and transition metals induce oxidative deterioration of biological macromolecules. Protein kinase C (PKC) may mediate these effects. However, no information is available regarding whether these xenobiotics can modulate PKC which is a critical event signaling the increase in endothelial permeability and cell proliferation. Female Sprague-Dawley rats were treated p.o. with two 0.25 LD50 doses of selected pesticides and transition metal salts at 0 and 21 h, and killed at 24 h. PKC activities were measured in liver and brain tissues. Cultured PC-12 cells were incubated for 24 h with 50, 100 or 200 nM concentrations of these pesticides, while 0.20, 0.40 or 0.60 microM concentrations of cadmium chloride (Cd(II)) and sodium dichromate (Cr(VI)) salts were employed. PKC activations were observed in the hepatic and brain cytosol fractions by all xenobiotics. Approximately 1.4- to 2.0-fold and 1.6- to 3.5-fold increases in PKC activity in the hepatic and brain cytosol fractions were observed, respectively. In the hepatic tissues, the greatest increases in activities were observed with TCDD, chlorpyrifos, endrin and Cd(II), while chlorpyrifos and fenthion exerted the greatest increases in the brain tissues. In cultured PC-12 cells, the greatest activation of PKC was observed primarily with 100-nM concentrations of the pesticides. The maximum effects were induced by chlorpyrifos, fenthion, Cd(II) and Cr(VI) salt. The results clearly indicate that pesticides as well as Cd(II) and Cr(VI) salts can modulate a vital component of the cell signaling pathway, namely PKC activity. PKC may be a target of free radicals and oxidative stress, leading to altered cell proliferation and differentiation.

Animals↗