M. K. K. Pillai

Trends in ambient levels of DDT and HCH residues in humans and the environment of Delhi, India.

Monitoring of DDT and HCH residues in abiotic and biotic components of the environment of Delhi during 1988 to 1989 revealed low to moderate levels of these insecticides in soil, earthworms, birds, buffalo milk, water, freshwater clams, fish, human fat, human blood and breast milk samples. Total HCH residues were less than those of DDT in all the samples. This survey indicates (in spite of the continued use of DDT and HCH in the country) a general decline in the levels of DDT residues in most of the samples studied when compared to previous surveys. Although the levels of DDT and HCH residues in fish and river water were below the permissible limits, those in human samples remained fairly high.

Effect of temperature and sunlight exposure on the fate of soil-applied [14C]-gamma-hexachlorocyclohexane

The role of temperature and solar radiation in the rapid dissipation ofγ-1,2,3,4,5,6-hexachlorocyclohexane (γ-HCH) from Indian soils was determined by quantifying volatilization, mineralization, binding and degradation of [14C]-HCH in a sandy loam soil. An increase in temperature from 15 to 45°C caused a 6-fold rise in volatilization. Degradation as well as mineralization of HCH increased with temperature, although both were minimal. Bound residues of HCH in soil increased from 3.3% at 15°C to 16.7% at 45°C, after 28 days. In flooded soils, volatile losses nearly doubled, while binding and mineralization decreased. Exposure of HCH-treated soil to sunlight in quartz tubes showed a two-fold increase in volatilization over the dark controls. Formation ofγ-2,3,4,5,6-pentachlorocyclohex-l-ene (γ-PCCH) in the unflooded soils andγ-3,4,5,6-tetrachlorocyclohex-1-ene (γ-TCCH) in the flooded systems were enhanced by sunlight. Trace amounts ofα-HCH were detected in the volatilized organics from the quartz tubes. Flooding the soil markedly increased volatile losses, thus leaving only 14% of the initial HCH as residues in soil after 42 days of exposure in quartz tubes. Neither flooding nor sunlight had any significant effect on HCH binding in soil. Mineralization, though amounting to a maximum of only 3% in the unflooded soil, was further reduced in submerged soils. The data demonstrate the significant influence of temperature, humidity and solar radiation, on the rapid loss of HCH from Indian subtropical soils, evidently by rapid volatilization.

INCORPORATION OF THYMIDINE INTO DNA OF THE GONADS IN THE NORMAL AND CHEMOSTERILIZED YELLOW-FEVER MOSQUITO

Effect of the chemosterilants, apholate and hempa, on the incorporation of tritiated thymidine in DNA of the gonads of Aedes aegypti was studied. Larval treatment with sterilizing doses of the chemosterilants caused inhibition of DNA synthesis in the gonads. The inhibition was found to be more in testes than in ovaries. The significance of these findings in relation to the mode of action of these chemosterilants is discussed.

Distribution, excretion, and metabolism of 14C-DDT in the larva and adult Trogoderma granarium in relation to toxicity

Abstract The larvae of the khapra beetle, Trogoderma granarium Everts were completely tolerant to DDT whereas the adults were much less tolerant. The mechanism of this differential toxicity was investigated. Both adults and larvae did not metabolize DDT and only unchanged insecticide was recovered from the insect body and excreta. The adult body retained about one and a half times more DDT and excreted it only at one-half the rate compared to that of the larvae. Further the central nervous system of adults contained two times as much or more DDT than that of the larvae. All of these factors may be responsible for the above-mentioned difference in the DDT toxicity.

Aldrin and Dieldrin Residues in Human Fat, Milk and Blood Serum Collected from Delhi

1 Aldrin and dieldrin residues were monitored in the fat, breast milk and blood serum from female residents of Delhi. 2 The average aldrin and dieldrin contents were 0.048 and 0.099 ppb in adipose tissue, 0.003 and 0.060 ppb in breast milk and 0.004 and 0.002 ppb in blood serum, respectively. 3 The older donors contained higher levels of aldrin and dieldrin in their adipose tissue. 4 Primagravidae contained more of these chemicals in their breast milk. 5 A positive correlation was observed between the aldrin concentration in adipose tissue and breast milk, and that in adipose tissue and blood serum. Similarly, a significant correlation was found between dieldrin in adipose tissue and blood serum. 6 The levels of aldrin and dieldrin were low in samples from residents of Delhi when compared to those in developed countries.

Dry aerial fallout of organochlorine insecticide residues in Delhi, India

Monitoring of airborne dust in Delhi during May to July 1985 revealed residues of DDT varying from 1.3 to 7.14 ng mg(-1) (4.06-22.31 ng m(-2) day(-1)) with an average of 3.32 ng mg(-1) (10.38 ng m(-2) day(-1)), and HCH which ranged from 0.46 to 2.35 ng mg(-1) (1.44-7.34 ng m(-2) day(-1)) with a mean of 1.16 ng mg(-1) (3.63 ng m(-2) day(-1)). The concentration of total DDT was almost 3 times greater than that of HCH.

EFFECT OF APHOLATE AND HEMPA ON NUCLEIC ACID AND PROTEIN SYNTHESES IN THE YELLOW‐FEVER MOSQUITO

The growth curve, nucleic acid and protein content of the various life stages of Aedes aegypti were studied. The larvae of this mosquito were treated with sterilizing doses of the chemosterilants apholate and hempa, and their effects on the above parameters were also investigated. The body‐weight increased gradually in the earlier instars and showed a sharp rise from late‐fourth instar to the pupa. Adults weighed less than the pupae Females weighed more than the males. In the controls, DNA and RNA content generally followed the growth curve. RNA content was more than DNA up to the late‐fourth instar and the ratio reversed in the later stages. Protein content also followed the growth curve except in adult female, where it was more than in the pupa. In general the treatment with the chemosterilants. apholate and hempa did not seem to alter RNA, DNA and protein content in the whole insect.

HAEMATOLOGICAL EFFECTS OF APHOLATE IN THE RED COTTON BUG, DYSDERCUS KOENIGII

Topical application of sterilizing doses of apholate causes haematological changes in the adults of Dysdercus koenigii. The normal males have less haemolymph (13–16 μl) than females (18–37 μl) for the first 120 hr of adult life. Apholate treatment significantly reduces the haemolymph volume of both the sexes. There are significantly more haemocytes in circulation in adult females than in males. The total haemocyte count shows an initial increase up to 48 hr, but later indicates a drastic reduction in the treated males and females. The plasmatocytes of the treated insects are found to reduce in numbers and the prohaemocytes become the predominant type, while in controls the plasmatocytes are the major type of haemocytes.

Aldrin and dieldrin in maternal serum, cord serum and breast milk in human samples from Delhi, India

Abstract Aldrin and dieldrin were monitored in samples of maternal serum, cord serum and mothers milk, collected from young mothers three days post partum. All mothers were permanent residents of Delhi. For the 25 donors, the average aldrin content was 0.40 ppb in breast milk, 0.17 ppb in maternal serum and 0.05 ppb in cord serum. The average dieldrin content was 0.13, 0.09 and 0.04 ppb in breast milk, maternal serum and cord serum, respectively. A significant correlation between the levels of aldrin and dieldrin was found in maternal milk and maternal serum, and maternal milk and cord serum. There was no significant correlation between maternal serum and cord serum.