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PubMed1994

Chlorinated hydrocarbons and shell thinning in eggs of (Accipiter) hawks in Ontario, 1986-1989.

Eggs of sharp-shinned hawks (Accipiter striatus), Cooper's hawks (A. cooperii), and northern goshawks (A. gentilis) were collected from nests in south-central Ontario from 1986 to 1989. Detectable levels of the chlorinated hydrocarbons DDE, DDT, DDD, mirex, photomirex, cis-nonachlor, trans-nonachlor, oxychlordane, dieldrin, heptachlor expoxide, HCB and PCB were present in all the eggs analyzed. Mean contaminant levels were highest in sharp-shinned hawks, slightly lower in Cooper's hawks, and significantly lower in goshawks; for example, mean DDE values were 7.23, 4.48 and 0.90 mg kg(-1) (wet weight), respectively. Total PCB levels were generally less than 1.5 mg kg(-1), lower than those associated with reproductive effects in field and laboratory studies with other species. Mean shell thicknesses of sharp-shinned and Cooper's hawk eggs were significantly less than mean pre-DDT era thicknesses (-10 and -8%, respectively), reductions that were probably not relevant to reproductive success. Goshawk eggs exhibited no significant reduction in shell thickness. Contaminant levels among the three species probably reflect differing food habits and migratory patterns.

Journal Article↗
PubMed1994

Organochlorine contaminants and eggshell thinning in grebes from prairie Canada.

Eggs of five species of grebe were collected from Manitoba, Saskatchewan and Alberta during 1982-1987: red-necked (Podiceps grisegena), horned (P. auritus), eared (P. caspicus), western (Aechmophorus occidentalis) and pied-billed (Podilymbus podiceps). DDE and PCBs were present in all samples analyzed, whereas dieldrin, mirex and oxychlordane were occasionally present at low levels. Mercury was present at low levels in all samples for which it was analyzed. Red-necked grebes nesting in Manitoba had the highest contaminant levels and, assuming that contaminant burdens were accumulated principally on the wintering grounds, the mean PCB:DDE ratio (3.1) indicated that these birds and those from sites in central and eastern Saskatchewan probably wintered on the Atlantic coast. Overall low contaminant levels and a low mean PCB:DDE ratio (1.4) in the eggs of red-necked grebes breeding in Alberta and western Saskatchewan suggested that these birds wintered on the Pacific coast. A similar pattern was apparent in horned and eared grebes. Concentrations of DDE and PCB were both significantly correlated with Ratcliffe index (shell thickness), and were strongly correlated with each other. Ratcliffe indices were determined for historical collections of red-necked grebe eggs. Eggshell thickness of grebes nesting in Manitoba declined significantly during the years following the introduction of DDT (post-1947) and has only recovered partially since it was banned in 1972. The Alberta-breeding population did not appear to have undergone any significant decrease in shell thickness.

Journal Article↗
PubMed1995

Can seal eating explain elevated levels of PCBs and organochlorine pesticides in walrus blubber from eastern Hudson Bay (Canada)?

Walrus (Odobenus rosmarus) blubber samples from Inukjuak and Akulivik (East Hudson Bay), Foxe Basin (Igloolik and Hall Beach) and Loks Land (East Baffin Island) were analysed for PCB congeners (ortho and non-ortho substituted) and other persistent organochlorines (DDT, toxaphene, chlordanes, dieldrin, mirex), as well as chlorinated dioxins/furans, to document spatial trends in contaminants in Canadian Arctic marine biota. Samples from 19 of 53 individuals had concentrations of SigmaPCBs greater than 1000 ng g(-1) (wet wt); the remaining individuals had much lower concentrations (50-600 ng g(-1)). Highest concentrations were found in samples from Inukjuak where average concentrations in blubber of females (N = 9) were 1450 +/- 954 ng g(-1) toxaphene, 2750 +/- 1780 ng g(-1) SigmaCHLOR, 2160 +/- 925 ng g(-1) SigmaDDT and 4790 +/- 2380 ng g(-1) SigmaPCB. SigmaPCB and SigmaDDT concentrations greater than 1000 ng g(-1) were unexpected based on previous studies of walrus from Greenland and Alaska. Local contamination was ruled out because levels of all organochlorines were elevated in each animal from Inukjuak, and elevated levels were also found in animals from Akulivik and Loks Land. Walrus from Inukjuak had sigma13C and sigma15N values in muscle intermediate between those of ringed seals (Phoca hispida) and those of walrus from Akulivik with low organochlorine levels. There was a weak but significant correlation between and sigma15N and (log)SigmaPCB. The Inukjuak walrus also had higher proportions of highly chlorinated PCB congeners, and higher DDE/SigmaDDT ratios than walrus from Igloolik or Akulivik. The results suggest that the walrus with elevated organochlorines are feeding at a higher trophic level than those with low levels and are probably utilizing ringed seals for a portion of their diet.

Journal Article↗
PubMed1996

Persistent organochlorines in beluga whales (Delphinapterus leucas) from the St Lawrence River estuary--I. Concentrations and patterns of specific PCBs, chlorinated pesticides and polychlorinated dibenzo-p-dioxins and dibenzofurans.

Blubber samples from beluga whales (Delphinapterus leucas) in the St Lawrence River estuary were analysed for PCB congeners (ortho- and non-ortho-substituted) and other persistent organochlorines as well as chlorinated dibenzo-dioxins/furans (PCDD/Fs). Major individual components (mean concentrations > 1 microg g(-1)) were 4,4'-DDE, -DDD and -DDT, T12 (a toxaphene-related compound), trans-nonachlor, oxychlordane, mirex, HCB, tris(p-chlorophenyl) methane and dieldrin. Concentrations of SigmaPCBs (8.3-412 microg g(-1)), SigmaDDT (3.36-389 microg g(-1)) and mirex (0.18-6.8 microg g(-1)) were particularly elevated relative to other odontocetes in Canadian waters. SigmaDDT, PCBs (as Aroclor), mirex and T12 concentrations were positively correlated with age of adult females (> 10 years) but only weakly, or not significantly, correlated with age of adult males. PCDD/Fs were present at low ng kg(-1) levels and consisted mainly of penta- and hexachlorofurans, and hepta- and octachlorodioxin. CB126 (3,3',4,4',5-PCB) was the most prominent non-ortho-substituted PCB congener in beluga blubber. Total TCDD toxic equivalents averaged 330 ng kg(-1) in females and 1400 ng kg(-1) in males and were dominated by CB126, and the mono-ortho-substituted congeners CB105 and CB118. Biomagnification factors (BMFs) for mirex and SigmaPCB from fish to beluga ranged from 11 to 16, and were similar to BMFs in Arctic animals, indicating that elevated levels in St Lawrence animals are a consequence of relatively high levels of recalcitrant organochlorines in prey of the beluga in the St Lawrence river system.

Journal Article↗
PubMed1996

Persistent organochlorines in beluga whales (Delphinapterus leucas) from the St Lawrence River estuary--II. Temporal trends, 1982-1994.

Blubber samples from 16 dead beluga whales (Delphinapterus leucas) collected during 1993-1994 in the St Lawrence River estuary were analysed for PCB congeners and other persistent organochlorines (DDT-group, chlorinated bornanes (toxaphene, CHB), chlordane SigmaCHL), hexachloro-cyclohexanes (SigmaHCH), chlorobenzenes (SigmaCBz), tris(p-chlorophenyl methane (TPMe) and mirex). Concentrations and relative proportions of major individual organochlorine components were within the same range as previous results for this population. Temporal trends were studied by combining the results with data from the analysis of 44 samples (1986-1990) and (for DDT and Aroclor PCBs only) with 20 samples (1982-1985) reported by Martineau et al., 1987. Results were lipid normalized and then age-adjusted by an ANCOVA model. Significant relationships between age and concentrations of most organochlorine groups were found for females but not for males. Significant declines were observed in SigmaDDT, and Aroclor PCBs (1.5- and 1.9-fold, respectively) in males between the 1982-1985 and 1993-1994 collection periods. Significant declines were also observed for SigmaHCH and SigmaCBz in males between 1986-1988 and 1993-1994. Mean concentrations of CHBs were significantly higher in 1993-1994 than in earlier years while dieldrin, SigmaCHL, mirex, and TPMe showed no trend. Declines in concentrations of major organochlorine groups were not observed in females possibly because of higher year to year, and within year, variation. The temporal trend in DDT and PCB concentrations in male beluga blubber paralleled trends in seals, eels, and seabirds in the St Lawrence estuary observed during the 1980s.

Journal Article↗
PubMed1996

Long-term trends and sources of organochlorine contamination in Canadian tundra Peregrine Falcons, Falco peregrinus tundrius.

Levels of eggshell thinning, and organochlorine residues in egg contents, blood plasma of adults and juveniles, tissue samples, and prey species were determined for a population of migratory Peregrine Falcons (Falco peregrinus tundrius) breeding in the Canadian Arctic. Temporal trends were assessed by comparing data collected during 1991-1994, with data from 1982-1986, for the same population. Shells (n=54) from 1991-1994 averaged 15% thinner than eggs produced prior to the introduction of DDT. No improvement in shell thickness was detected between decades. Mean DDE residue levels in eggs showed a decline from 7.6 mg kg (1982-1986) to 4.5 mg kg (1991-1994), but there was no significant change in SigmaPCB residues. Moreover, the proportion of clutches with eggs exceeding critical SigmaPCB, DDE, and dieldrin residue levels (10%) did not change between decades. Relative to Greenland and Alaskan populations, F. p. tundrius at Rankin Inlet show high levels of organochlorine contamination and little reduction in residues over the last decade. These Tundra Peregrines continue to be exposed to organochlorines in Latin America; however, results also link relatively high levels in the study population with waterfowl species that do not leave Canada in winter.

Journal Article↗
PubMed1983

Evaluation of FAO/WHO pesticide standards in relation to Polish and Honduran diets.

The FAO/WHO Codex Alimentarius Commission publishes a Guide to Codex Maximum Limits for Pesticide Residues (1978) which gives both acceptable daily intake (ADI) values and maximum residue limit (MRL) values for many pesticides in raw agricultural commodities (rac's) from crops on which their use is approved. ADI values are determined from animal toxicology data which given a no-observable-effect level (NOEL) and use of a safety factor. Specific MRL values are calculated from the ADI and a food factor (F), which is the decimal fraction of that rac in the assumed typical diet. One of the difficulties with this procedure is that dietary patterns differ substantially between countries. Whatever dietary pattern is assumed in calculation of the MRLs may be inappropriate for that country. Theoretical maximum residue intakes (TMRIs) were calculated from the Codex ADIs and MRLs using F values calculated from the national dietary patterns published separately in Poland and Honduras. The equation is TMRI = sigma MRLi X Fi X D, where D is the daily individual diet weight of rac's in kilograms for the particular country. The TMRI should be lower than the maximum permitted intake (MPI) calculated as MPI = ADI X 60, where the 60 is an arbitrary human body weight in kilograms. The TMRI exceeded the MPI for 16 of 33 pesticides used in Poland and for 10 of 20 used in Honduras. At the extreme, the Polish TMRI/MPI ratio for aldrin--dieldrin is 19.5 and 18.1 for fenithion; nine pesticides had ratios of 4.0 or higher.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Should the presence of carcinogens in breast milk discourage breast feeding?

Pollutant chemicals are commonly found in human milk at levels that would prevent its sale as a commercial food for infants. The chemicals found most commonly are dichlorodiphenyl-dichloroethene, polychlorinated biphenyls, dieldrin, chlordane, heptachlor, and polychlorinated dibenzodioxins. In general, the regulatory levels for these chemicals have been set to prevent cancer in adult humans from lifetime exposure. We compared lives saved in the postneonatal period by breast feeding to the estimated excess cancer deaths attributable to the contaminants in breast milk. The results of this analysis suggest that only extreme levels of contaminants in breast milk represent more of a hazard than failure to breast feed, but clinical considerations in individual cases might override this conclusion. Our analysis depends on assumptions about how the chemicals might cause cancer in humans and on whether breast feeding prevents some postneonatal mortality. Noncarcinogenic hazards from chemical exposure, other hazards from breast feeding such as transmission of viruses, and benefits of breast feeding other than reduction in mortality were not considered.

Breast Feeding↗
PubMed1980

Chlorphentermine uptake by rabbit lung slices.

Slices of rabbit lung tissue (approximately 150 mg; 0.5 mm) were incubated in 5 ml of Krebs-Ringer phosphate buffer, in the presence of 0.25 mM [14C]chlorphentermine (CP) with shaking at 37 degrees C and under an atmosphere of an O2/CO2 mixture (95 : 5). Incubation medium (M) and tissue (T) were analyzed for radioactivity. Uptake of CP reached a plateau after 30 min at a T/M ratio of 20. Upon varying the concentration of [14C]CP from 0.125 mM to 2 mM, the concentration-response curve was seen to saturate and the T/M ratio decreased with increasing concentration. Substituting LiCl for NaCl or increasing the K+ content in the medium decreased CP uptake. Incubation of slices with Na+-pump inhibitors, harmaline and iodoacetate, significantly decreased CP uptake. Chloroamphetamine, desimipramine, imipramine, morphine, chlorpromazine, dieldrin, methadone, amphetamine (each at 1 mM) and incubation at 10 degrees C inhibited CP uptake. Imipramine and amphetamine were both effective in displacing previously accumulated CP from the tissue slices. Efflux of CP from the lung slices was biphasic and was not affected by removal of Na+ from the medium. Binding of CP to lung homogenate was unaffected by substituting LiCl for NaCl or by the presence of 1 mM iodoacetate. However, 1 mM harmaline or 1 mM imipramine decreased CP binding. These studies offer evidence for a partially Na+-dependent, active uptake process for pulmonary sequestration of CP compatible with earlier findings obtained with perfused intact lung preparations.

Animals↗
PubMed1983

The effect of ethanol on the absorption, accumulation and biotransformation of xenobiotics by the isolated perfused rabbit lung.

The effects of acutely administered ethanol on absorption, accumulation and biotransformation of several model compounds were examined in the isolated perfused lung (IPL). To determine pulmonary accumulation imipramine and paraquat were studied. To determine the effect of ethanol on the absorption of substances from the airways into the blood sulfanilic acid was used as an example of a relatively lipid soluble compound while mannitol was chosen as a non-lipid soluble compound. Aldrin was chosen to demonstrate the effects of circulating ethanol on pulmonary biotransformation. The results obtained with imipramine and paraquat indicate that after a 60-min perfusion period 93% and 20% of the original amount added are respectively lost from the blood perfusate. Ethanol at an initial concentration of 300 mg/100 ml has no apparent effect either on the rate or the quantities accumulated by the lungs. When sulfanilic or mannitol were administered into the airways both compounds appeared in the perfusate and ethanol had no effect on this absorption. Finally we obtained evidence that aldrin is converted to dieldrin by the IPL but that the quantities metabolized are not modified by the presence of ethanol.

Absorption↗
PubMed1984

Screening of potential reproductive toxicants by use of porcine granulosa cell cultures.

While approximately 60 000 chemicals are in widespread use with 1000 new chemicals introduced into the environment each year, the biologic effects of these agents are poorly understood. With the specific goal of testing for potential reproductive toxicity, we have established methodology for the screening of compounds in vitro by measuring effects on progesterone production by porcine granulosa cells in culture. Granulosa cells were harvested by mechanical agitation, cryopreserved, and cells with known progesterone production capacity utilized for culture. Agents to be tested were added to cultures of 10(5) cells and the media assayed for progesterone by radioimmunoassay. Estradiol suppression of progesterone production was easily demonstrated in this system and utilized as a verification of responsiveness. The pesticide o,p-DDT and its isomer p,p-DDT produced dramatic suppression of progesterone production apparently with equal potencies to estradiol. By contrast, the pesticides malathion, parathion and dieldrin and the fungicide hexachlorobenzene were without effect in this test system.

Animals↗
PubMed1975

Attempted suicide with a pesticide mixture.

An attemped suicide with a pesticide mixture containing pentachlorophenol, benzene hexachloride, dieldrin, metaldehyde phenoxyacetate esters, paraquat, diquat and petroleum distillates, is reported. The prognosis initially seemed hopeless, but the patient was treated successfully by intensive care with early respiratory assistance.

Adult↗
PubMed1995

Actions of picrotoxinin analogues on an expressed, homo-oligomeric GABA receptor of Drosophila melanogaster.

The actions of picrotoxinin and four of its analogues were tested on a Drosophila melanogaster homo-oligomeric GABA (gamma-aminobutyric acid) receptor formed when RDL (resistance to dieldrin) subunits were expressed in Xenopus oocytes. In agreement with previously reported studies on native insect GABA receptors and native expressed vertebrate GABA receptors, acetylation of the bridgehead hydroxyl group (picrotoxinin acetate) greatly reduced the activity of the molecule, but surprisingly, substitution with flourine at the same position also reduced the activity. Conversion of the terminal isopropenyl group to an acetyl (alpha-picrotoxinone) or hydration of the double bond (picrotin) also reduced activity, in agreement with findings for native insect and mammalian receptors. The present results suggest that interactions of convulsants with homo-oligomeric and multimeric GABA receptors are qualitatively similar. Thus, the RDL homo-oligomer exhibits a pharmacological profile for picrotoxinin analogues resembling that of native GABA receptors.

Acetylation↗
PubMed1983

The effects of twenty-two organochlorine pesticides as inducers of the hepatic drug-metabolizing enzymes.

The effects of 22 organohalogen pesticides as inducers of hepatic drug-metabolizing enzymes in the immature male Wistar rat have been determined, this group includes four isomeric hexachlorocyclohexanes, technical chlordane, alpha-chlordane, gamma-chlordane, oxychlordane, trans-nonachlor, heptachlor, heptachlor epoxide, aldrin, dieldrin, kepone, toxaphene, mirex, hexachlorobenzene (HCB) and several DDT analogs. With the exception of HCB, all of the pesticides induced microsomal dimethylaminoantipyrine, N-demethylase and aldrin epoxidase activities and the cytochrome P-450 content of microsomes from animals pretreated with most of the compounds was also increased compared to control rats. These pesticides all resembled phenobarbitone in their mode of induction. The effects of HCB as a microsomal enzyme inducer resembled those observed after coadministration of phenobarbitone plus 3-methylcholanthrene.

Animals↗
PubMed1987

The effects of organochlorine pesticides as inducers of testosterone and benzo[a]pyrene hydroxylases.

p,p'-DDE, phenobarbital, dieldrin heptachlor, chlordane and toxaphene induced rat liver microsomes exhibited increased formation of the 4,5-dihydrodiol, 3,6-quinone, 9- and 3-hydroxymetabolites of benzo[a]pyrene and the latter three compounds also induced an increase in the rate of formation of the 9,10-dihydrodiol metabolite. Lindane was inactive as an inducer of benzo[a]pyrene hydroxylase. With the exception of lindane, all the organochlorine pesticides and PB induced testosterone 16 alpha- and 16 beta-hydroxylases; in contrast lindane induced testosterone 6 alpha-, 7 alpha- and 6 beta-hydroxylases and PB also induced testosterone 15 beta-hydroxylase and androstenedione formation. Using a battery of monooxygenase enzyme assays it was evident that there were significant differences between PB and several organochlorine pesticides as inducers of rat hepatic cytochrome P-450-dependent monooxygenases.

Aminopyrine N-Demethylase↗
PubMed1987

Analysis of organochlorine pesticides, polychlorinated biphenyls, dibenzo-p-dioxins and dibenzofurans in human milk by extraction with the lipophilic gel Lipidex 5000.

A method for multicomponent determination of organochlorine contaminants in human milk is described. The lipophilic gel Lipidex 5000 was used for extraction of lipids and organochlorine compounds. Further purification and separation was achieved by chromatography on partly deactivated aluminium oxide, Lipidex, silica gel and active basic and acidic aluminium oxide. The concentrations of pesticides and polychlorinated biphenyls (PCBs) were determined by electron-capture gas chromatography. Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were determined by selected-ion monitoring capillary column gas chromatography-mass spectrometry at a resolution of 8000-9000. The levels of 2,2-bis(4-chlorophenyl)-1,1,1-trichloroethane, 1,1-bis(4-chlorophenyl)-2,2-dichloroethene, hexachlorobenzene, alpha-hexachlorocyclohexane, beta-hexachlorocyclohexane, dieldrin, trans-nonachlor, oxychlordane and PCBs found by this method agreed with the levels determined using a previous solvent-extraction method. Recovery experiments were performed by addition of pentachlorophenol and certain PCDDs and PCDFs. The average recovery of 0.5-2.0 ng pentachlorophenol per ml milk was 92%. Ten PCDDs and PCDFs reported to occur in milk were added at levels between 0.5 and 50 pg per ml milk. Recoveries of these compounds were on an average 79-91%.

Aluminum Oxide↗
PubMed1985

Species variations in the metabolism of liposoluble organochlorine compounds by hepatic microsomal monooxygenase: comparative kinetics in four vertebrate species.

Liposoluble organochlorine compounds were used as substrates in a kinetic study of the hepatic microsomal monooxygenases of the male rat, feral pigeon (Columbia livia), frog (Rana pipiens) and rainbow trout (Salmo gairdnerii). Substrate concentrations were taken down to environmentally realistic levels. Lineweaver-Burk plots gave straight lines for both aldrin (HHDN) and the dieldrin analogue HCE. For both substrates activities followed the order rat greater than feral pigeon greater than trout over the entire concentration range. The metabolism of PCB isomers in microsomes from these uninduced animals was very slow. These results give evidence of cytochrome P-450 forms which can metabolize organochlorine compounds at low substrate concentrations.

Animals↗
PubMed1993

Lindane decreases forskolin-stimulated cyclic AMP accumulation but does not modify Gs in rat enterocytes.

Treatment of isolated rat enterocytes with the halogenated insecticide lindane (the gamma-isomer of hexachlorocyclohexane, HCCH) did not modify the general membrane fluidity (as estimated by a fluorescence polarization technique) nor the guanine nucleotide binding regulatory protein Gs (as studied by both ADP-ribosylation of its alpha subunit by cholera toxin and Gpp[NH]p stimulation of membrane adenylate cyclase activity). However, lindane decreased in a dose-dependent manner the effect of the diterpene forskolin on direct activation of the adenylate cyclase catalytic subunit. After 5 min of cell treatment with 0.5 mM lindane, the maximal stimulatory effect of forskolin (at 100 microM) decreased by about 50%. There was a certain degree of specificity since delta-HCCH was indeed more potent, whereas dieldrin and endrin (non-lindane related halogenated compounds) behaved as lindane, and alpha- and beta-HCCH were poorly efficient on the inhibition of forskolin stimulation of adenylate cyclase activity. A similar effect of lindane was observed on receptor-stimulated cyclic AMP accumulation by using vasoactive intestinal peptide instead of forskolin. The results on a non-receptor mediated effect of lindane on the adenylate cyclase catalytic subunit itself could be related to: (i) alterations of membrane microdomains surrounding this and other integral proteins which would result in modifications of their activities; and/or (ii) a reciprocal relation between the two main routes of signal transduction so that the activation of protein kinase C (or other Ca(2+)-dependent protein kinases) by lindane would lead to phosphorylation of the adenylate cyclase catalytic subunit.(ABSTRACT TRUNCATED AT 250 WORDS)

1-Methyl-3-isobutylxanthine↗