Michael S. Amato

Quantile regression in environmental health: Early life lead exposure and end-of-grade exams.

Conditional means regression, including ordinary least squares (OLS), provides an incomplete picture of exposure-response relationships particularly if the primary interest resides in the tail ends of the distribution of the outcome. Quantile regression (QR) offers an alternative methodological approach in which the influence of independent covariates on the outcome can be specified at any location along the distribution of the outcome. We implemented QR to examine heterogeneity in the influence of early childhood lead exposure on reading and math standardized fourth grade tests. In children from two urban school districts (n=1,076), lead exposure was associated with an 18.00 point decrease (95% CI: -48.72, -3.32) at the 10th quantile of reading scores, and a 7.50 point decrease (95% CI: -15.58, 2.07) at the 90th quantile. Wald tests indicated significant heterogeneity of the coefficients across the distribution of quantiles. Math scores did not show heterogeneity of coefficients, but there was a significant difference in the lead effect at the 10th (β=-17.00, 95% CI: -32.13, -3.27) versus 90th (β=-4.50, 95% CI: -10.55, 4.50) quantiles. Our results indicate that lead exposure has a greater effect for children in the lower tail of exam scores, a result that is masked by conditional means approaches.

Early lead exposure (<3 years old) prospectively predicts fourth grade school suspension in Milwaukee, Wisconsin (USA).

School suspensions are associated with negative student outcomes. Environmental lead exposure increases hyperactivity and sensory defensiveness, two traits likely to increase classroom misbehavior and subsequent discipline. Childhood Blood Lead Level (BLL) test results categorized urban fourth graders as exposed (2687; lifetime max BLL 10-20 µg/dL) or unexposed (1076; no lifetime BLL ≥5 µg/dL). Exposed children were over twice as likely as unexposed children to be suspended (OR=2.66, 95% CI=[2.12, 3.32]), controlling for covariates. African American children were more likely to be suspended than white children, but lead exposure explained 23% of the racial discipline gap. These results suggest that different rates of environmental lead exposure may contribute to the racial discipline gap.

Moderate lead exposure and elementary school end-of-grade examination performance

PURPOSE This study investigated the association between moderate lead poisoning in early childhood with performance on a comprehensive set of end-of-grade examinations at the elementary school level in two urban school districts. METHODS Children born between 1996 and 2000 who resided in Milwaukee or Racine, WI, with a record of a blood lead test before the age of 3 years were considered for the analysis. Children were defined as exposed (blood lead level ≥10 and <20 μg/dL) or not exposed (BLL < 5 μg/dL). Parents of eligible children were mailed surveys to consent to participation and elicit information on potential confounders. On consent, children were matched to educational records for fourth grade Wisconsin Knowledge and Concepts Examinations. Seemingly unrelated regression was used to evaluate the relation between scaled scores on all sections of the examination (math, reading, language arts, science, and social studies) with exposure status, controlling for demographics, social status indicators, health indicators, and district-based poverty indicators. RESULTS A total of 1133 families responded to the survey and consented to have educational records released; 43% of children were considered exposed. After controlling for demographic and socioeconomic covariates, lead exposure was associated with significantly lower scores in all sections of the Wisconsin Knowledge and Concepts Examinations (range: science, β = -5.21, P = .01; reading, β = -8.91, P = .003). Children who were black, had a parent with less than a high-school education, and were classified by parents as having less than excellent health had significantly lower performance on all examination components. CONCLUSIONS Children with moderate lead poisoning in early childhood performed significantly lower on all components of elementary school end-of-grade examinations compared with unexposed children. Household level social status and childhood health indicators partially explain decreased examination scores.

Incorporating Information Exposure Into a Theory of Planned Behavior Model to Enrich Understanding of Proenvironmental Behavior

This study proposes including variables related to information exposure as background variables in a theory of planned behavior (TPB) model. Minimizing the spread of aquatic invasive species by anglers provides context. A survey was administered to anglers that included TPB and information channel items. Regression analysis found that exposure to information from different channels was associated with TPB variables, though the direction and strength varied. Including information exposure in a TPB model may clarify underlying mechanisms in environmental behavior change campaigns.

The challenge of self-enhancement bias for educational programs designed to encourage natural shorelines

Abstract This study proposed and found support for a potential barrier to successful implementation of programs designed to promote natural shorelines along residential property. Increased residential development around lakeshores in the Upper Midwest is associated with reduced wildlife habitat, lower biodiversity, and degraded water quality compared to undeveloped shorelines. Property owners can reduce the impact of shoreline development through personal choices, such as planting native vegetation or allowing natural flora to regrow. Various educational programs encouraging more natural shorelines have been implemented; however, evaluative research on their success and studies about improving these programs are scant. This study explored how the phenomenon of self-enhancement bias may cause property owners to over-estimate the natural state of their shorelines, preventing remedial action they otherwise might take if a more accurate self-assessment were available. Surveys were mailed to 212 property owners on 2 lakes in northwest Wisconsin. Biologists’ assessments of the “naturalness” of each property parcels shoreline were compared with survey data from residents indicating their own perceptions about how natural their shorelines were. Results revealed that residents evaluated their own shorelines significantly more natural than did the biologists. This pattern is consistent with the hypothesis that self-enhancement bias may be a barrier to educational programs designed to encourage more natural shorelines among lakeshore property owners. Based on these findings, the authors offer recommendations for lake and water resource managers to potentially improve the efficacy of such programs.

Property owner beliefs and goals related to shoreline maintenance behaviors

Abstract Amato MS, Shaw BR, Haack J, Moore CF. 2015. Property owner beliefs and goals related to shoreline maintenance behaviors. Lake Reserv Manage. 31:44–49. Individual differences in shoreline maintenance behaviors are likely partially attributable to individual differences in relevant beliefs and goals. Lake property owners can help reduce the impact of development by maintaining a vegetated buffer on their shoreline, as opposed to grooming an expansive manicured lawn. A survey mailed to residential lake property owners in Wisconsin (n returned = 155, response rate = 64%) measured lake-specific beliefs and goals and self-reported frequency of engaging in 4 behaviors counterproductive to shoreline health. Analysis revealed those counterproductive behaviors were negatively associated with endorsement of biospheric beliefs and positively associated with stated relevance of human usage goals (p < 0.01 for all). Recommendations for lake managers and environmental educators, particularly the importance of aesthetic preferences, are discussed.