Linking ecological impact to metal concentrations and speciation: a microcosm experiment using a salt marsh meiofaunal community.

Microcosm experiments addressed the impact of a mixture of Cu, Cr, Cd, Pb, and Hg at three concentrations after 36 h, 12 d, and 30 d on a meiofauna-dominated salt marsh community. In addition to analyzing effects on meiofaunal abundances, the study quantified the sediment metal concentrations of all five metals and pore-water concentrations, speciation, and ligand complexation of Cu. Abundances of deposit feeders such as the polychaete Streblospio benedicti, gastropods, and bivalves were impacted at lower metal concentrations than the mainly algal-feeding copepods, ostracods, and nematodes. We suggest that this might be due to bulk ingestion of metal-contaminated sediments resulting in relatively higher metal exposure in the deposit feeders than in the other, nondeposit feeding taxa. Copepod and ostracod abundances decreased only in the highest metal treatment, where levels of inorganic Cu ([Cu']) in pore waters were similar to levels associated with both acute and subacute toxicity in published in vivo toxicity studies of marine copepods. The higher metal treatments yielded disproportionately higher pore-water [Cu] compared with sediment [Cu], suggesting saturation of sediment-associated ligands with increased additions of Cu. Similarly, the higher metal treatments appeared to reach saturation of the organic Cu ligands, with the excess pore-water [Cu] present in the more toxic, inorganic species of Cu. Acid-volatile sulfide (AVS) concentrations at sediment horizons inhabited by meiofauna were low and AVS was not considered a significant metal ligand at these depths. Since meiofauna are predominantly associated with oxic surface sediments, it is doubtful that AVS is a major factor controlling availability of free metal for exposure to these taxa.

Determination of Mirex in human blood serum containing polychlorinated biphenyls by using packed column gas chromatography.

An analytical method has been developed that uses electron capture/gas-liquid chromatography to determine Mirex in serum containing polychlorinated biphenyls (PCBs) (Aroclor 1260). With this method, 0.2 ppb Mirex can be determined in 4 mL serum that also contains 10 ppb PCBs. The method provides approximately 70% recovery of Mirex at 1.0 and 3.5 ppb. The coefficients of variation are 4.5 and 4.6% at 1.0 and 3.5 ppb, respectively. In a cooperative study with the Ohio Department of Health, the Centers for Disease Control used this method to determine the extent of exposure of Salem, OH, residents to Mirex. Confirmation of Mirex was obtained by using high resolution gas chromatography and high resolution mass spectrometry.

Indoor air mercury concentrations following application of interior latex paint.

Mercury vapors are released from paint containing mercury compounds used to prolong the shelf-life of interior latex paint. To determine whether homes recently painted with paint containing mercury had elevated indoor-air mercury concentrations, we studied 37 Ohio homes. Twenty-one homes painted with mercury-containing paint a median of 86 days earlier were compared with 16 homes not recently painted with mercury-containing paint. Paint samples from the exposed homes contained a median of 210 mg Hg/L (range 120-610 mg/L). The median air mercury concentration was higher in the exposed homes (0.3 microgram/m3; range nondetectable--1.5 microgram/m3) than in the unexposed homes (nondetectable; range nondetectable--0.3 microgram/m3, P less than 0.0001). Among the exposed homes there were seven in which paint containing less than 200 mg/L had been applied. In these homes, the median air mercury concentration was 0.2 microgram/m3 (range nondetectable--1 microgram/m3). Six (33%) exposed homes had air mercury concentrations greater than 0.5 microgram/m3, the acceptable indoor concentration recommended by the Agency for Toxic Substances and Disease Registry. Elemental mercury was the form of mercury released into the air. These data demonstrate that potentially hazardous mercury exposure may occur in homes recently painted with paint that contains mercury concentrations less than 200 mg/L.