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At least 163 records · Page 9Linked to original sources
PubMed2003

Fish tissue quality in the lower Mississippi River and health risks from fish consumption.

Between 1990 and 1994, samples of three shellfish species (i.e. blue crab, Callinectes sapidus;crayfish, Procambarus acutis; and river shrimp, Macrobrachium ohionii) and 16 fish species and were collected at six sites along the lower Mississippi River by the Louisiana Department of Environmental Quality, Office of Water Resources in coordination with the US Environmental Protection Agency. The fish species included: bigmouth buffalo (Ictiobus cyanellus); blue catfish (Ictalurus furcatus); carp (Cyprinus carpio); channel catfish (Ictalurus punctatus); cobia (Rachycentron canadum); flathead catfish (Pylodictis olivaris); freshwater drum (Aplodinotus grunniens); largemouth bass (Micropterus salmoides); long nose gar (Lepisosteus osseus); red drum (Sciaenops ocellatus); red snapper (Lutjanus campechanus); smallmouth buffalo (Ictiobus bubalus); spotted gar (Lepisosteus oculatus); striped bass (Morone saxatilis); white bass (Morone chrysops); and white crappie (Pomoxis annularis). Organic compound and heavy metal concentrations were measured in 161 composite fish tissue samples where each composite included three to 10 individual fish. Nineteen chemicals, found at measurable levels in sample tissues, were used in calculations of lifetime excess cancer and non-cancer risks due to fish consumption. We calculated: 574 chemical-specific cancer risks; 41 total cancer risks; and 697 margins of exposure based on a consumption rate of one 8-ounce meal per week (0.032 kg/day), a body weight of 70 kg and reported cancer potency factors and reference doses. We identified nine species of concern (blue catfish, carp, channel catfish, cobia, crayfish, flathead catfish, red drum, spotted gar and striped bass) based on total cancer risk greater than 10(-4) or margin of exposure greater than 1, and whether or not samples collected in subsequent years resulted in lower risks. The compounds primarily responsible for the elevated risks were aldrin, dieldrin, alpha-benzene hexachloride, gamma-benzene hexachloride, heptachlor epoxide, arsenic and mercury.

Animals↗
PubMed2000

Interventions for treating scabies.

BACKGROUND: Scabies is a common public health problem with an estimated prevalence of 300 million. Infestation can cause considerable discomfort and intense itching. Severe adverse effects have been reported for some drugs used to treat scabies. OBJECTIVES: The objective of this review is to assess the effects and toxicity of topical and systemic drug treatment for scabies. SEARCH STRATEGY: We searched the Cochrane Infectious Diseases Group trials register, the Cochrane Controlled Trials Register, Medline, Embase, military records, traditional medicine databases. We also contacted international specialist centres and drug manufacturers. SELECTION CRITERIA: Randomised controlled trials of any drug treatment for scabies. Tolerability and toxicity were sought in any study of humans taking any drug treatments for scabies. DATA COLLECTION AND ANALYSIS: Two reviewers assessed trial quality and extracted data. MAIN RESULTS: Eleven trials were included (7 compared drug treatments, 2 compared treatment regimes, 1 compared the drug vehicle and 1 was a community intervention). Compared with placebo in one small trial, ivermectin was associated with a significant higher clinical cure rate at seven days. Permethrin appeared to be more effective than crotamiton for clinical and parasitic cure rates. Permethrin appeared to be better than gamma benzene hexachloride for clinical cure rates in two small trials but had no advantage in the largest trial (test for heterogeneity p< 0.001). Permethrin also appeared more effective in reducing itch persistance than gamma benzene hexachloride. There appeared to be no difference in clinical cure rates between crotamiton and gamma benzene hexachloride. Single trials assessed: the effectiveness of oral versus topical treatment (ivermectin versus benzyl benzoate); treatment vehicle (pork fat versus cold cream); and mass community treatment (ivermectin) but were too small to demonstrate an effect. No randomised trials of malathion were identified. Serious adverse drug reactions (including death and convulsions) have been reported in other studies of scabies drugs, most notably gamma benzene hexachoride and ivermectin. REVIEWER'S CONCLUSIONS: The evidence that permethrin is more effective than gamma benzene hexachloride is inconsistent. Permethrin appears to have less potential serious drugs reactions than gamma benzene hexachloride although this is not derived from trial data. More research is needed of the safety and effectiveness of ivermectin and malathion compared to permethrin, on community management, and on different regimes and vehicles for topical treatment.

Hexachlorocyclohexane↗
PubMedDate not supplied

Distribution of isomers of BHC and related histopathology of liver in hexachlorocyclohexane (technical grade BHC) fed mice.

In an attempt to correlate body burden and related liver histopathology after exposure to 500 ppm benzene hexachloride, 6- to 8-wk-old male and female mice were fed benzene hexachloride with their mash diet for a 6-month period. The mice were divided into 8 groups (12/group; 6 experimental, 6 control) and were sacrificed by group monthly. During the first month, 3 groups of mice were sacrificed after 10, 20, and 30 days of treatment, respectively. A dose-related increase in liver weight was found in test animals (P less than .01). The histopathology of liver showed clear, oval cells; hypertrophied cells with foci; and neoplastic nodules that were apparent during the final 3- to 6-month period. Few oval and hypertrophied cells were found in control animals. The alpha isomer concentration of benzene hexachloride rose during the first 2 months of treatment, but declined after that time. A transient rise was noted for the beta isomer concentration of benzene hexachloride at the end of the 6-month period. The gamma isomer concentration was elevated during the initial 3 months of treatment, but declined during the subsequent 3 months. The results present definitive changes suggestive of precancerous states.

Animals↗
PubMed2005

Susceptibility of Amblyomma variegatum ticks to acaricides in Ghana.

Abstract. The susceptibility of unfed and fed stages of larvae, nymphs and adult females of Amblyomma variegatum ticks were tested using Shaw's filter paper dip method against four acaricides; chlorfenvinphos and dioxathion, chlorfenvinphos, gamma benzene hexachloride and amitraz at four different concentrations including the recommended dose rates. Based on their lethal concentrations (LC50 & LC90) chlorfenvinphos and dioxathion combined and chlorfenvinphos alone placed first and second, respectively, in all stages except at the unfed nymphal stage where gamma benzene hexachloride topped with a LC50 of 0.001629, while chlorfenvinphos and dioxathion combined and chlorfenvinphos alone had LC50 of 0.001794 and 0.002258, respectively. Amitraz appeared to have a quick knock-down effect on larvae and nymphs but at the recommended dose rate, showed no mortality of the ticks at that stage. However, at a concentration of 0.040%, amitraz showed a 100% inhibition of oviposition and hatching of laid eggs. Gamma benzene hexachloride produced only 66% inhibition of oviposition while chlorfenvinphos and dioxathion combined and chlorfenvinphos alone produced 100% inhibition of oviposition at their recommended dose rates. Fed nymphs were more susceptible than the unfed nymphs. Eggs laid by engorged female ovipositing ticks, applied with gamma benzene hexachloride, hatched.

Animals↗
PubMed1991

Topical steroid induced chronic demodicidosis.

We report a 39-year-old female patient who developed pruritic erythematous telangiectatic patches with scaly follicular papules on the neck and upper chest for 4 years. Ten per cent potassium hydroxide preparation of skin scrapings revealed Demodex folliculorum. Histology showed three Demodex mites in one of the hair follicles. She was treated with a topical steroid without improvement. The skin lesions and Demodex mite disappeared after a single application of 1 per cent gamma benzene hexachloride but twice daily application of 1 per cent gamma benzene hexachloride for 2 weeks was needed to prevent recurrence.

Administration, Topical↗
PubMed1963

CHLORINATED INSECTICIDES IN THE BODY FAT OF PEOPLE IN THE UNITED STATES.

Benzene hexachloride and dieldrin are present in the body fat of people in the general population of the United States. The mean concentration of dieldrin is 0.15 +/- 0.02 parts per million, which is in good agreement with the concentration reported for southern England. The mean concentration of benzene hexachloride is 0.20 +/- 0.04 ppm, which is considerably lower than the mean concentration reported for France. Paired analyses of DDT by gas chromatographic and colorimetric methods show that the results of the latter may give incorrectly high results when applied to human fat.

Adipose Tissue↗
PubMed1993

Phagocytic activity of Dictyostelium amoebae treated with an organochlorine pesticide.

The effect of an organochlorine pesticide benzene hexachloride (containing alpha, beta, gamma and delta isomers) on the phagocytic activity of the vegetative cells of Dictyostelium discoideum was investigated. Benzene hexachloride (BHC) at concentrations of 60 ppm and above inhibited the phagocytic activity as revealed by 3H-labelled E. coli uptake. The BHC treated cells also showed smaller and delayed plaque formation. Interactions of lipophilic pesticide with the hydrophobic cell surface presumably alters the receptor mediated phagocytosis of Dictyostelium amoebae.

Animals↗
PubMed1983

Lindane bioassay studies and human cancer risk assessment.

Benzene hexachloride or hexachlorocyclohexane comes in eight isomeric forms which differ in the spatial positions of the chlorine atoms on the boat and chair forms. Only one, however, gamma-isomer (lindane) possesses relevant insecticidal activity. The majority of studies on the potential carcinogenicity of benzene hexachloride, however, did not discriminate between the various isomers because they assumed that carcinogenicity is independent of steric structure. Also, proper differentiation between morphologic endpoints was not duly carried out and considered. The present evaluation of lindane's biologic activity was restricted to the lifelong studies in which pure lindane (greater than 99.5%) was utilized and the morphology of the observed lesions, mainly in the liver, were classified according to their biologic behavior into hyperplastic, benign neoplastic, and malignant entities. None of the studies gave evidence that lindane was carcinogenic in mice and rats. An enhancement of benign liver tumors (tumorigenic effect) was observed only in CF1 male mice (17/56 at the only tested dose: 400 ppm vs. 3/89 observed in the nontreated controls). Dose-response function of this tumor response in conjunction with two other lifetime studies (80 and 160 ppm in B6C3F1 and 50, 25, and 12.5 ppm in NMRI mice) were best described by the Weibull model, giving a relatively high estimate of its shape parameter (m = 2.5). Assuming similar susceptibility of humans to lindane and considering maximal occupational exposure to this agent (professional applicators), the probability of lindane associated tumor development was estimated as 2.2 X 10(-10). Because this cancer risk is five orders of magnitude below the acceptable health risk, this evaluation concludes that environmental exposure to lindane does not pose a threat to human health.

Animals↗
PubMed1977

Racial stratification of organochlorine insecticide residues in human adipose tissue.

The racial stratification of residues of total DDT equivalent, heptachlor epoxide, oxychlordane, dieldrin, beta-benzene hexachloride and lindane in human adipose tissue was studied. Samples of human adipose tissue were obtained from locations selected in the contiguous United States according to a stratified, proportionate-random survey design and chemically analyzed for selected organochlorine pesticides. The most marked case of racial difference in residue level was total DDT equivalent. Samples from Negros contained almost twice as much of this chemical as did samples from Caucasians. Racial stratification also was found in the frequency of lindane. Lindane was detected about twice as often in samples from Negros than in samples from Caucasians. Little racial differences were noted for residues of beta-benzene hexachloride, heptachlor epoxide, dieldrin and oxychlordane.

Adipose Tissue↗
PubMed1996

Semivolatile organic compounds in adipose tissue: estimated averages for the US population and selected subpopulations.

OBJECTIVES: The fiscal year (FY) 1986 Environmental Protection Agency National Human Adipose Tissue Survey (NHATS) was conducted to estimate average concentrations of 111 semivolatiles in human adipose tissue within the US general population and selected subpopulations. METHODS: Population and subpopulation estimates of average semivolatile concentrations were established from 671 adipose tissue specimens pooled across 50 analytical samples. RESULTS: Among polychlorinated biphenyls (PCBs), average concentrations for the group aged 45 and older were from 188% to 706% higher than for the 0- through 14-year-old age group. Similar increases with age were observed for pesticides. Geographic effects on average concentration were mixed, and no significant race or sex effects were observed. Statistically significant increases from FY 1982 NHATS results were observed for PCBs and hexachlorobenzene, whereas a decrease from FY 1982 was significant for beta-BHC (benzene hexachloride). Increases from FY 1984 NHATS results were significant for p,p-DDT (dichlordiphenylethylene), p,p-DDE (dichlordiphenyldichlor), hexachlorobenzene, and PCBs. CONCLUSIONS: The survey establishes baseline average levels of semivolatile compounds in the adipose tissue of US residents.

Adipose Tissue↗