Ecotoxicity quantitative structure-activity relationships for alcohol ethoxylate mixtures based on substance-specific toxicity predictions

Traditionally, ecotoxicity quantitative structure-activity relationships (QSARs) for alcohol ethoxylate (AE) surfactants have been developed by assigning the measured ecotoxicity for commercial products to the average structures (alkyl chain length and ethoxylate chain length) of these materials. Acute Daphnia magna toxicity tests for binary mixtures indicate that mixtures are more toxic than the individual AE substances corresponding with their average structures (due to the nonlinear relation of toxicity with structure). Consequently, the ecotoxicity value (expressed as effects concentration) attributed to the average structures that are used to develop the existing QSARs is expected to be too low. A new QSAR technique for complex substances, which interprets the mixture toxicity with regard to the "ethoxymers" distribution (i.e., the individual AE components) rather than the average structure, was developed. This new technique was then applied to develop new AE ecotoxicity QSARs for invertebrates, fish, and mesocosms. Despite the higher complexity, the fit and accuracy of the new QSARs are at least as good as those for the existing QSARs based on the same data set. As expected from typical ethoxymer distributions of commercial AEs, the new QSAR generally predicts less toxicity than the QSARs based on average structure.     

Low-level ozone exposure and respiratory symptoms in infants

OBJECTIVE: Recent studies indicate that the U.S. Environmental Protection Agency (EPA) ozone standards may not protect sensitive individuals. In this study we examined respiratory effects of ozone in infants who may be vulnerable, particularly if they are children of asthmatic mothers. DESIGN: Women delivering babies at one of five hospitals in southwestern Virginia between 1994 and 1996 were invited to participate in a cohort study; 780 women enrolled. Ambient air quality data (ozone and particulate matter) were collected at a central monitoring site. PARTICIPANTS: This analysis is of 691 infants followed for approximately 83 days between 10 June and 31 August 1995 and/or 1996 ; they contributed a total of 52,421 infant-days of follow-up. Mothers were interviewed at enrollment and approximately biweekly to report infants' daily symptoms. Repeated measures logistic regression models were run separately for wheeze, difficulty breathing, and cough. Ozone metrics included 24-hr average, peak 1-hr, and maximum 8-hr average. Analyses were repeated for the 61 infants whose mothers had asthma. RESULTS: For every interquartile-range increase in same-day 24-hr average ozone, likelihood of wheeze increased 37% [95% confidence interval (CI), 2-84%]. Among infants of asthmatic mothers, same-day 24-hr average ozone increased likelihood of wheeze 59% (95% CI, 1-154%) and of difficulty breathing 83% (95% CI, 42-136%). Maximum 8-hr ozone and peak 1-hr ozone were associated with difficulty breathing, but not wheeze, in infants of asthmatic mothers. Ozone was not associated with cough. CONCLUSIONS: At levels of ozone exposure near or below current U.S. EPA standards, infants are at increased risk of respiratory symptoms, particularly infants whose mothers have physician-diagnosed asthma.     

Asthma hospitalization rates among children, and school building conditions, by New York State school districts, 1991-2001

School-age children spend a significant portion of their day at school where they can be exposed to asthma triggers, but little information exists regarding potential relationships between childhood asthma and school environmental factors. This study examined patterns of asthma hospitalization and possible factors contributing to asthma hospitalizations, including sociodemographics and school environmental factors, among school-age children (5-18 years) in New York State (NYS) over an 11-year period (1991-2001). Asthma hospitalization data from the Statewide Planning and Research Cooperative System and the 1990 and 2000 census population files were geocoded into NYS school districts statewide, and school district asthma hospitalization rates were then calculated. Building Condition Survey for each school was then utilized to create summary measures of school building conditions for each school district. Hospitalization rates were linked to district school building conditions by using logistic regression analysis that controlled for poverty. Calculation of time trends revealed overall declines in asthma rates among school-age children for NYS from 1991 to 2001. This general decline was found in each sociodemographic group. The mean rate for NYS from 1991 to 2001 was 27/10,000. Poorly rated building systems that were significantly associated with increased school district asthma hospitalization rates were roofing (odds ratio [OR] = 1.76; 95% confidence interval [CI(95)] = 1.13-2.74), windows (OR = 1.66; CI(95)= 1.08-2.54), exterior walls (OR = 2.24; CI(95)= 1.31-3.83), floor finishes (OR = 1.75; CI(95)= 1.14-2.69), and boiler/furnace (OR = 1.71; CI(95)= 1.99-2.94). This does not indicate a definite link between these systems and asthma hospitalizations since the available building system information is very general and crude.     

Acute and Chronic Toxicity of Alcohol Ethoxylates to the Green Alga, Desmodesmus (=Scenedesmus) subspicatus, and the Subsequent Development of Structure Activity Relationships

No abstract available.