BackgroundPhthalates may pose a risk for perinatal developmental effects. An important question relates to the choice of suitable biological matrices for assessing exposure during this period.ObjectivesThis study was designed to measure the concentrations of phthalate diesters or their metabolites in breast milk, blood or serum, and urine and to evaluate their suitability for assessing perinatal exposure to phthalates.MethodsIn 2001, 2–3 weeks after delivery, 42 Swedish primipara provided breast milk, blood, and urine samples at home. Special care was taken to minimize contamination with phthalates (e.g., use of a special breast milk pump, heat treatment of glassware and needles, addition of phosphoric acid).ResultsPhthalate diesters and metabolites in milk and blood or serum, if detected, were present at concentrations close to the limit of detection. By contrast, most phthalate metabolites were detectable in urine at concentrations comparable to those from the general population in the United States and in Germany. No correlations existed between urine concentrations and those found in milk or blood/serum for single phthalate metabolites. Our data are at odds with a previous study documenting frequent detection and comparatively high concentrations of phthalate metabolites in Finnish and Danish mothers’ milk.ConclusionsConcentrations of phthalate metabolites in urine are more informative than those in milk or serum. Furthermore, collection of milk or blood may be associated with discomfort and potential technical problems such as contamination (unless oxidative metabolites are measured). Although urine is a suitable matrix for health-related phthalate monitoring, urinary concentrations in nursing mothers cannot be used to estimate exposure to phthalates through milk ingestion by breast-fed infants.

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Two strains of bacteria capable of carrying out the 0-methylation of phenolic compounds, one from the gram-positive genus Rhodococcus and one from the gram-negative genus Acinetobacter, were used to examine the 0-methylation of phenols carrying fluoro-, chloro-, and bromo-substituents. Zero-order rates of 0methylation were calculated from data for the chloroand bromophenols; there was no simple relationship between the rates of reaction and the structure of the substrates, and significant differences were observed in the responses of the two test organisms. For the gram-negative strain, the pattern of substitution was as important as the number of substituents. Hexachlorophene was resistant to 0-methylation by both strains, and tetrabromobisphenol-A was 0-methylated only by the gram-positive strain. It is suggested that in the natural environment, bacterial 0-methylation of phenols carrying electron-attracting substituents might be a significant alternative to biodegradation.

Two strains of bacteria, provisionally assigned to the genus Arthrobacter, were shown to metabolize mono-, di-, tri-, and tetrachloroguaiacols and pentachlorophenol to the corresponding 0-methyl compounds. Hydroxylated intermediates were formed only transiently, except for the synthesis by one strain of 3,4,5trichlorosyringol from 3,4,5-trichloroguaiacol. Two isomeric trichloroveratroles and tetrachloroveratrole were formed by three of the strains from a highmolecular-weight chlorinated lignin isolated from kraft pulp mill bleach plant. The concentrations of methylated metabolites varied widely and did not appear to be correlated with degradation. The possible environmental consequences resulting from synthesis of these highly lipophilic substances are discussed briefly.

We have demonstrated that strains of bacteria belonging to the genera Pseudomonas and Acinetobacter possessed the ability to transform, by O-methylation, components of spent bleachery effluent such as 4,5,6-trichloroguaiacol and high molecular weight chlorinated lignin. O-Methylation could be enhanced by the presence of a cosubstrate such as succinate or 4-hydroxybenzoate. We have used zebra fish (Brachydanio rerio) to examine bioconcentration potential, toxicity to embryos and larvae, and the sensitivity of the offspring of exposed adults. Bioconcentration factors (total wet weight) on a logarithmic scale were 3.5 and 4.4 for 3,4,5-trichloroveratrole and tetrachloroveratrole, respectively. The potential for bioconcentration of the other neutral metabolites was inferred from estimated values of the octanol–water partition coefficients. 3,4,5-Trichloroveratrole, tetrachloroveratrole, pentachloroanisole, and 1,2,3-trichloro-4,5,6-trimethoxybenzene had threshold toxic concentrations to zebra fish embryos and larvae of 450, 100, 2.8, and 450 μg∙L−1, respectively, and all of them were capable of inducing, at somewhat lower concentrations, various deformations including curvature of the larvae and distortion of the notochord. Experiments on the effect of preexposure of adults to tetrachloroveratrole at a concentration of 16 μg∙L−1 showed that the offspring were adversely affected, e.g. in a decreased viability of the embryos, lowered median survival time for larvae, and greater sensitivity to tetrachloroveratrole. Both 3,4,5-trichloroveratrole (5–150 μg∙kg liver fat−1) and tetrachloroveratrole (40–400 μg∙kg liver fat−1) were detected in fish from localities subjected to discharge of bleachery effluent, and were absent in fish from uncontaminated localities. Identification of these compounds was based on gas chromatographic, and for tetrachloroveratrole, mass spectrometric, comparison with authentic compounds. We conclude that not only compounds present in bleachery effluent, but those that may be produced in the environment by bacterial O-methylation, have potentially hazardous biological activities. These results shed fresh light on a hitherto neglected aspect of environmental hazard assessment, and we suggest that data for a given compound must be supplemented with that for metabolites that could be produced in the environment.

Metabolically stable consortia of anaerobic bacteria obtained by enrichment of sediment samples with 3,4,5-trimethoxybenzoate (TMBA), 3,4,5-trihydroxybenzoate (gallate [GA]), or 5-chlorovanillin (CV) were used to study the anaerobic transformation of a series of chloroveratroles, chloroguaiacols, and chlorocatechols used as cosubstrates. Experiments were carried out with growing cultures, and the following pathways were demonstrated for metabolism of the growth substrates: (i) TMBA produced GA, which was further degraded without the formation of aromatic intermediates; (ii) GA formed pyrogallol, which was stable to further transformation; and (iii) CV was degraded by a series of steps involving de-O-methylation, oxidation of the aldehyde group, and decarboxylation to 3-chlorocatechol before ring cleavage. Mono-de-O-methylation of the cosubstrates occurred rapidly in the order 4,5,6-trichloroguaiacol > 3,4,5-trichloroguaiacol 3,4,5trichloroveratroletetrachloroveratrole > tetrachloroguaiacol and was concomitant with degradation of the growth substrates. For the polymethoxy compounds-chloroveratroles, 1,2,3-trichloro-4,5,6-trimethoxybenzene, and 4,5,6-trichlorosyringol-de-0-methylation took place sequentially. The resulting chlorocatechols were stable to further transformation until the cultures had exhausted the growth substrates; selective dechlorination then occurred with the formation of 3,5-dichlorocatechol from 3,4,5-trichlorocatechol and of 3,4,6-trichlorocatechol from tetrachlorocatechol. 2,4,5-, 2,4,6-, and 3,4,5-trichoroanisole and 2,3,4,5tetrachloroanisole were de-O-methylated, but the resulting chlorophenols were resistant to dechlorination. These results extend those of a previous study with spiked sediment samples and their endogenous microflora and illustrate some of the transformations of chloroguaiacols and chlorocatechols which may be expected to occur in anaerobic sediments.

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