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Levels of non-ortho-polychlorinated biphenyls (PCB), some mono-ortho-PCB, and resolved peaks of tetrato heptachloronaphthalenes are reported in biological and sediment samples from the Swedish environment. The results show that levels of individual PCB congeners, and especially PCB 126, may pose a greater threat to the environment than the 2,3,7,8-chlorinated dioxins and furans when expressed as 2,3,7,8-tetrachlorodibenzodioxin (TCDD) toxic equivalents. Polychlorinated naphthalenes are as widespread pollutants as PCB, and at some locations the pollution situation indicates a specific source, leading to a bioaccumulating hexachloronaphthalene contributing considerably to the total TCDD-like toxicity. A time trend study of guillemot eggs from the Baltic Proper seems to indicate that levels of non-ortho-PCB and -PCN have decreased since the 1970s.

Reaction with hydroxyl radicals (OH) is the major pathway for removal of cyclic volatile methyl siloxanes (cVMS) from air. We present new measurements of second‐order rate constants for reactions of the cVMS octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) with OH determined at temperatures between 313 and 353 K. Our measurements were made using the method of relative rates with cyclohexane as a reference substance and were conducted in a 140‐mL gas‐phase reaction chamber with online mass spectrometry analysis. When extrapolated to 298 K, our measured reaction rate constants of D4 and D5 with the OH radical are 1.9 × 10−12 (95% confidence interval (CI): (1.7–2.2) × 10−12) and 2.6 × 10−12 (CI: (2.3–2.9) × 10−12) cm3 molecule−1 s−1, respectively, which are 1.9× and 1.7× faster than previous measurements. Our measured rate constant for D6 is 2.8 × 10−12 (CI: (2.5–3.2) × 10−12) cm3 molecule−1 s−1 and to our knowledge there are no comparable laboratory measurements in the literature. Reaction rates for D5 were 33% higher than for D4 (CI: 30–37%), whereas the rates for D6 were only 8% higher than for D5 (CI: 5–10%). The activation energies of the reactions of D4, D5, and D6 with OH were not statistically different and had a value of 4300 ± 2800 J/mol.

SwedenExtracts of gasoline and diesel vehicle exhaust and ambient air particles were fractionated into five fractions according to polarity on a silica gel column. Two medium polar fractions showing high genotoxic activity in the Ames test were further subfractionated, using normal-phase high-performance liquid chromatography. Chemical analyses were performed by means of gas chromatography combined with mass spectrometry and flame ionization and detection. The crude extracts, fractions, and subfractions were assayed with the Ames test, with and without S9, and the most abundant compounds in the subfractions are reported. -Environ Health Perspect 1 02(Suppl 4): 85-92 (1994).