Residual levels, phase distributions, and human health risks of OCPs in the middle reach of the Huai River, China

Are the residues of organochlorine pesticides (OCPs) in freshwater in China still of concern after prohibition and restriction for decades? The scarcity of monitoring data on OCPs in freshwater in China over the past few years has hampered understanding of this issue. In this study, water and suspended particulate matter (SPM) samples were collected from the middle reach of the Huai River for OCP analyses. Residues of ∑OCPs in water and SPM ranged from ND to 8.6 ng L-1 and 0.50 to 179 ng L-1, with mean concentrations of 1.7 ± 1.3 ng L-1 and 6.1 ± 31 ng L-1, respectively. ∑HCHs (α-, β-, γ-, and δ-HCH) and ∑HEPTs (heptachlor and heptachlor epoxide) were the most predominant pesticides in the dissolved phase and SPM, respectively, accounting for 43 ± 35% and 27 ± 29% of ∑OCPs. HCHs and heptachlor epoxide mainly existed in the dissolved phase, while heptachlor mainly existed in SPM. The isomeric composition pattern of HCHs in water differed from that in SPM. Briefly, β-HCH dominated in water, while δ-HCH dominated in SPM. However, the composition pattern of DDT and its metabolites in water was similar to that in SPM. o,p'-DDD and p,p'-DDE dominated in both water and SPM. The ratios of α-/γ-HCH and (DDD + DDE)/DDTs indicated that HCHs and DDTs were mainly derived from historical residues. Risk assessments indicated that OCPs may not pose carcinogenic and non-carcinogenic risks to residents.

Histopathology of carcinomas of the liver in mice ingesting heptachlor or heptachlor epoxide

C3H male and female mice, ingesting 10 ppm of the pesticides heptachlor or heptachlor epoxide in the diet, developed highly significant incidences of carcinomas of the liver. The carcinomas varied from well-differentiated to poorly differentiated and undifferentiated and were capable of invasion and metastasis.

[Investigations on the influence of insecticides on autoxidation processes. X. Formation of peroxides from octadecenic acid methylester in the presence of water and chlorinated hydrocarbon insecticides (author's transl)]

According to the range DDT less than DDE less than heptachlor less than heptachlorepoxide, chlorinated hydrocarbon insecticides promote the formation of peroxides from cis- and trans-9-octadecenic acid methylesters within the lipid and the water phase of the investigated model system. Compared with DDT and heptachlor the metabolites DDE and heptachlorepoxide proof as more efficient prooxidants; this may be explained by their higher reactivity. According with these observations the amount of insecticides, especially of heptachlor and heptachlorepoxide, that can be extracted from the model system with petroleumether after 72 hrs of autoxidation is markedly diminished. From that it is concluded, that in the investigated lipid-water-system the insecticides not only have a catalytic effect, but also are in part immediately involved in the formation of peroxides from 9-octadecenic acid methyl ester.

[Investigations on the influence of insecticides on autoxidation processes. XI. Formation of secondary metabolites from octadecenic acid methyl ester in the presence of water and chlorinated hydrocarbon insecticides (author's transl)]

For determining the influence of chlorinated hydrocarbon insecticides on the formation of secondary metabolites from peroxidized 9-octadecenic acid methylester by autoxidation within 72 hrs, substances reacting with phosphomolybdanic acid have been separated by TLC. Furthermore the increase of metabolites containing carbonyl groups and the variation of the ratio of polar to unpolar OH-groups in the metabolites have been determined by IR-spectrophotometry. All results proved, that the trans-9-octedecenic acid ester is autoxidized more rapidly than the cis-ester. Moreover the insecticides principally favour the formation of secondary metabolites from the lipidperoxide. This effect increases in the range DDT, DDE, heptachlor, heptachlorepoxide. If the increase of metabolites with carbonyl groups is chosen as a measure for the prooxidative effect, the effect appears equally high for the cis- and the trans-ester. But the hydroxyl index is changed depending on the kind of the insecticide added and the steric configuration of the lipid.

Abnormalities in the microsomal oxidases of the WHO standard reference strain of Musca domestica

Observations made during biochemical and toxicological studies of the housefly, in which the WHO standard reference (SR) strain was used as a standard, indicated that this strain differs from other strains in certain physiological and toxicological aspects. Experiments are described in which microsomal oxidases prepared from the standard reference strain and several other housefly strains, both susceptible and resistant to insecticides, were compared for heat stability, sensitivity to ionic strength, pH optima, and the spectral characteristics of their cytochrome P-450. In a comparison with 8 strains the SR strain microsomes were more stable at high incubation temperatures (40-47.5 degrees C). Compared to two other strains (NAIDM, susceptible, and Isolan-B, resistant) SR was more stable at low pH and more sensitive to high ionic strength. In spectral comparisons with NAIDM and Isolan-B, SR was found to contain microsomal cytochrome P-450 that differed slightly in its carbon monoxide or octylamine binding spectra. The results suggest that this strain may not provide a suitable reference in studies involving the microsomal oxidases. However, these apparent differences should not reduce the value of the SR stain as a reference in insecticide resistance studies.