Environmental cancer in the Indian context--an overview.

Problems related to environmental carcinogenesis have begun to surface with increased industrial activity and diffusion of hazardous chemicals. Cancer Registries maintained in some of our cities can help in retrospectively analysing incidence and related aetiology. Even a casual analysis of the existing data related aetiology. Even a casual analysis of the existing data belies the oversimplicity of the WHO model used in developing countries to asign lower priority to cancer prevention and control than to communicable diseases. Exposure data to environmental inducers of cancer, radiations, chemicals and other stresses is urgently needed. Prevention strategy should be more and more on a scientific base for an early detection and risk estimates of chemical exposures. Sustained environmental monitoring for inducers and cofactors are required. The Factory Act must make provision for appropriate health surveillance of workers over a long period.

Biological effects of chemical disasters : Human victims

A conceptual model is persented for a systems approach to the study of the biological effects of massive chemical exposures. The effects on the pulmonary system and on the skin are of immediate concern in accidents where toxic gases are released into ambient air of the neighbourhood. Detoxification function will have to be assessed and manipulated for successful antidotal therapy mutagenic effects including cancer and behavioural disturbances have to be ploying epidemiological techniques.(AU)

Metabolic activity of lysosomes in tin-intoxicated regenerating rat liver.

The metabolic activity of lysosomes was monitored by assaying the lysosomal enzymes. DNase, RNase, acid phosphatase and cathepsin in rat liver regenerating after partial hepatectomy at various intervals after the operation. Results of the present study demonstrate that the activities of lysosomal enzymes are increased significantly during the process of rapid regeneration, especially at 24 h and 48 h. A small rise in enzymatic activities was noticed at 36 and 72 h of regeneration, leading towards normalisation at 168 h. Administration of tin(II) tartrate (25 mu mol Sn2+/100 gm body wt.) significantly increased the DNAse and RNAse activity at 24 h of the regeneration, while a decrease was noticed in acid phosphatase activity. An increase was also found in the catheptic activity of tin-treated hepatectomized rats. It can thus be concluded that an increased metabolic activity of lysosomes is reflected by the increased activity of its hydrolytic enzymes during the regeneration, and tin at low concentrations is helpful to this process. Further work is in progress to gain insight into the other metabolic activity of the lysosomes during the process of regeneration.

Comparative studies on ecotoxicology of synthetic detergents.

To predict the comparative toxicological response of synthetic detergents on aquatic ecosystems, the effects of various concentrations of neutralized alkyl benzene sulfonate were studied. The median tolerance limit at 48 hr, 95% confidence limit, slope function, presumable harmless concentration, and rate of survival of different species of aquatic fauna such as water fleas (Daphnia magna), mosquito larvae (Culex pipiens), slug worms (Tubifex rivulorum), snails (Lymnaea vulgaris), tadpoles (Rana cyanophlyctis), and fish fingerlings (Cirrhina mrigala) were followed at 0, 24, 48, 72, and 96 hr. Any effect on quality of the water was also tested after the addition of various concentrations of detergents. The results showed that water fleas are more susceptible to detergent toxicity than fish fingerlings, tadpoles, slug worms, snails, and mosquito larvae. Behavioral changes were also observed as an index for detergent toxicity. The relative toxicity of the detergents to various species is discussed in relation to selective ecotoxicological response.

Xenobiotic biotransformation in wild birds: activity, induction, characterization and comparison with rat and mouse microsomal enzymes.

1. Benzo[a]pyrene hydroxylase, aminopyrine demethylase and glutathione S-transferase activities in hepatic and extrahepatic tissues of five wild birds, rat and mouse were compared. 2. Hepatic benzo[a]pyrene hydroxylase of wild pigeon was at least three times higher than that of rat or mouse. Hepatic aminopyrine demethylase and GSH S-transferase activities of wild birds were lower than those of rodents. 3. Renal GSH S-transferase of wild birds was 2-3 times more than in rat and mouse. 4. Avian benzo[a]pyrene hydroxylase activity of hepatic and renal tissue was linear up to 3.0 mg enzyme protein with pH optima of 7.4 and 7.2, at 42 degrees C. Apparent Km values were 11.76 and 3.33 microM respectively. 5. Hepatic enzyme activity was induced four-fold by 3-methylcholanthrene and about two-fold by phenobarbitone administration.

Storage of DDT and BHC in adipose tissue of Indian males.

Adipose tissue of 50 human subjects (10 to 60 years old) were taken from autopsy cases and analysed by gas-liquid chromatography equipped with an electron capture detector (3H +) for determination of storage levels of BHC (benzene hexa chloride), DDT (dichlorodiphenyl trichloroethane) and its metabolites DDE and DDD in human body fat. The data is reported according to age (length of exposure), dietetic habits and area of residence of the subjects. The results show relatively moderate exposure to DDT and BHC. Levels of residues were slightly higher in non-vegetarian and rural residents than those of their counterpart vegetarian and urban inhabitants. The study suggests that DDT levels in human adipose show a decreasing trend as compared to earlier report of Dale et al. of highest body burden of pesticides being present in indians.

In vitro screening of potential anti-cancer chemicals: effect of purine pyrimidine analogues on seed germination.

Germinating Cicer arietinum seeds were used to simulate embryonic tissue for evaluating toxicity of purine and pyrimidine analogues. 6-Mercaptopurine stimulated germination, whereas 8-azaadenine, 8-azaguanine, 2,6-diaminopurine, 6-amino, 2-hydroxypurine and 5-fluorouracil inhibited germination. 6-Methyluracil, 5-aminouracil and methylxanthines, viz. caffeine, theophylline, theobromine and uric acid exhibited little inhibitory effects. RNA synthesis ensued immediately after water imbibition and reached maximum at 12 h of germination. 2,6-Diaminopurine, 8-azaadenine, 8-azaguanine and 5-fluorouracil inhibited RNA synthesis. Cyclic-AMP, adenosine, indole-3-acetic acid (IAA) and folic acid partially reversed the inhibitory effects produced by purine pyrimidine analogues. Several hitherto untested pyrimidine analogues inhibited germination as well as RNA synthesis. Inhibition of Escherichia coli dihydrofolate reductase was used for purposes of comparison.

Organochlorine pesticides in specimens from women undergoing spontaneous abortion, premature of full-term delivery.

Organochlorine insecticides (BHC, aldrin, p,p'-DDE, p,p'-DDD, p,p'-DDT) were measured in the blood, placenta and fetus of women experiencing spontaneous abortions, preterm labor or full-term labor using an electron-capture gas chromatographic method. The following trend was found for insecticide concentrations in each of the specimens tested: spontaneous abortions greater than preterm greater than full-term. One conclusion of this work is that the organochlorine insecticides act as antagonists to pregnancy. A plausible explanation for the facilitory role of organochlorine insecticides in the initiation of preterm labor/abortion is hypothesized.

An inhibitor of lipid peroxidation in rat lungs.

Formation of lipid peroxides in vitro was investigated in the lung, liver, and brain homogenates of normal male rats. Unlike brain tissue, increasing the concentration of lung or liver in homogenates resulted in decreased output of lipid peroxides. Further, lung homogenates exerted an inhibition of lipid peroxide formation by brain and dilute liver homogenates. The factor responsible for such inhibition was located in the postmitochondrial supernatant, was heat stable, nondialysable, could be preserved in frozen state for 60 days, concentrated by dialysis against powdered sucrose, and precipitated by ammonium sulphate.