Toxics Use Reduction in the Home: Lessons Learned from Household Exposure Studies

Workers and fence-line communities have been the first to benefit from the substantial reductions in toxic chemical use and byproducts in industrial production resulting from the Massachusetts Toxics Use Reduction Act (TURA). As TURA motivates reformulation of products as well as retooling of production processes, benefits could extend more broadly to large-scale reductions in everyday exposures for the general population. Household exposure studies, including those conducted by Silent Spring Institute, show that people are exposed to complex mixtures of indoor toxics from building materials and a myriad of consumer products. Pollutants in homes are likely to have multiple health effects because many are classified as endocrine disrupting compounds (EDCs), with the ability to interfere with the body’s hormone system. Product-related EDCs measured in homes include phthalates, halogenated flame retardants, and alkylphenols. Silent Spring Institute’s chemical analysis of personal care and cleaning products confirms many are potential sources of EDCs, highlighting the need for a more comprehensive toxics use reduction (TUR) approach to reduce those exposures. Toxics use reduction targeted at EDCs in consumer products has the potential to substantially reduce occupational and residential exposures. The lessons that have emerged from household exposure research can inform improved chemicals management policies at the state and national levels, leading to safer products and widespread health and environmental benefits.     

Does interspecific competition influence relationships between heterozygosity and fitness-related behaviors in juvenile Atlantic salmon (<Emphasis Type="Italic">Salmo salar</Emphasis>)?

Very few studies have investigated the effect of genetic diversity on the behavioral and phenotypic traits linked to the competitive ability of individuals. In this study, we reared juvenile Atlantic salmon (Salmo salar) alone or with the competitive rainbow trout (Oncorhynchus mykiss) in order to: (1) to assess correlations between heterozygosity and traits related to individual competitive ability [i.e., heterozygosity–fitness correlations (HFCs)] in Atlantic salmon, and (2) to evaluate the effect of the competitive rainbow trout on any such HFCs. We also tested whether a few loci had a disproportionately large effect (i.e., the local effect hypothesis) or, on the contrary, if all loci contributed equally (i.e., the global effect hypothesis) in explaining the observed HFCs. We found significant HFCs for phenotypic traits related to the competitive ability of juvenile Atlantic salmon, i.e., the growth rate and the distance to the feeding source. Some HFCs were nonlinear, suggesting that individuals with intermediate levels of heterozygosity were favored. In addition, we found that the competition exerted by rainbow trout only weakly modified these HFCs as the relationships were highly consistent across treatments. We demonstrated that the local-effect hypothesis best explained both linear and nonlinear HFCs. Overall, our results illustrated the importance of genetic diversity in explaining the behavioral variability observed within populations. Moreover, we provide evidence that, even if a competitive species can have strong ecological effects, the relationships between genetic diversity and fitness-related traits in juvenile Atlantic salmon were not influenced by such effects.     

Effects of pharmaceuticals on Daphnia survival, growth, and reproduction

Pharmaceuticals have been globally detected in surface waters, and the ecological impacts of these biologically-active, ubiquitous chemicals are largely unknown. To evaluate the aquatic toxicity of individual pharmaceuticals and mixtures, we performed single species laboratory toxicity tests with Daphnia magna, a common freshwater zooplankton. We conducted acute (6-day) and chronic (30-day) exposure pharmaceutical bioassays and evaluated survivorship and morphology of adults and neonates, adult length, resting egg production, brood size (fecundity), and the proportion of male broods produced (sex ratio). In general, exposure to a single pharmaceutical in the 1-100 microg/l range yielded no apparent effects on the normal life processes of Daphnia. However, chronic fluoxetine exposure (36 microg/l) significantly increased Daphnia fecundity, and acute clofibric acid exposure (10 microg/l) significantly increased sex ratio. A mixture of fluoxetine (36 microg/l) and clofibric acid (100 microg/l) caused significant mortality; the same fluoxetine concentration mixed with 10 microg/l clofibric acid resulted in significant deformities, including malformed carapaces and swimming setae. Mixtures of three to five antibiotics (total antibiotic concentration 30-500 microg/l) elicited changes in Daphnia sex ratio. We conclude: (1) individual and mixtures of pharmaceuticals affect normal development and reproduction of Daphnia magna, (2) aquatic toxicity of pharmaceutical mixtures can be unpredictable and complex compared to individual pharmaceutical effects, and (3) timing and duration of pharmaceutical exposure influence aquatic toxicity.