Pharmacology Research in Environmental Signaling: Life Expectancy, Invisible Lead Dust, and Proactive Intervention to Reduce Children’s Pb Exposure in New Orleans, LA (USA)

Pharmacology is the study and research into the chemistry of life. This paper discusses the environmental signaling and external chemicals utilizing internal signals.There is no known safe level of lead exposure. Lead contact is determined clinically by measuring blood as a biomarker to determine exposure. The standard follow-up to excessive lead exposure is a reactive intervention of the individual’s residential house. The intervention method has been deemed ineffective at reducing children’s lead exposure. Measuring lead in the environment of communities along with the blood lead biomarker serves an alternative environmental signaling approach for assessing the source and inform a proactive method for curtailing exposure. The goals of this paper are: to describe environmental signaling for unearthing New Orleans’s lead problem, to explore the influence of a large natural flooding event on the environment and children’s lead exposure in the city, and to apply the knowledge acquired to reduce children’s lead exposure in lead contaminated communities of the city.

potential source of lead dust [7]. One consequence is that lead dust from contaminated soil is re-suspended into the air in late summer and early fall becoming a lead exposure source manifesting as "children's summer disease" [8].
The discussion section describes additional details about numerous clinical consequences that support the reality of lead exposure as an ongoing detriment to wellness, especially to very young children.
There is a critical need for effective interventions to prevent lead exposure. The common approach to intervention is to treat lead exposure at an individual residential house-by-house basis but this approach for reducing exposure has been judged ineffective [9,10]. Effective primary lead prevention of children's exposure requires new concepts and actions. The goal of this paper is to describe environmental signaling as a process to unearth the lead problem in New Orleans, to explore the influence of a large natural Hurricane event on environmental signaling in the city, and to apply that knowledge toward reducing children's exposure in lead contaminated communities of the city.

Environmental Measurement and Lead Exposure Signaling
This study builds on a unique opportunity to learn from an urban scale natural experiment. The flooding of 80% of its residential communities by Hurricane Katrina in late August 2005, New Orleans underwent soil changes, housing renovation, and cleanup. The datasets obtained before and ten years after the catastrophic flooding provide the basis for a rare chance to study lead dust and associated health outcomes at the scale of communities of an entire metropolitan area. Along with environmental samples the surveys include children's blood lead results.
Biomonitoring data for children's exposure results used in this study were collected (per protocols established by the CDC) by Louisiana Healthy Homes and Childhood Lead Poisoning Prevention (LHHCLPP).

Environmental sample collection and preparation
Pre-Katrina, the research team collected soil at the rate of 19 samples per census tract from the entire New Orleans metropolitan area, south of Lake Pontchartrain. By 2000 a soil lead map was completed for the city [11]. All samples were collected from the top 2.5 cm and systematically collected from four locations; busy roads (no samples from intersections), residential roads (no samples from intersections), mid yard or play areas, and house sides. Sample extraction was by trace metal grade nitric acid, and inorganic analysis was conducted with a Spectro Ciros® Inductively Coupled Plasma Emission Spectrometer (ICP-ES). Detailed methods about extraction and analysis are published [11]. The 2000 map is the basis for the pre-Katrina data used in this study. The biomonitoring data provided by LHHCLPP was stratified by census tracts and matched with soil lead data. Post-Katrina, 10 years after the flood, the same research team was reestablished to survey and remap post-Katrina Orleans Parish. In addition to the same personnel, the same procedures and analytical instrumentation were used as for the 2000 survey of the city. The advantage of having the same personnel and laboratory instrumentation for the post-Katrina survey is that it increases confidence in the comparability of the results. As in the case with the pre-Katrina survey, children's biomonitoring data from LHHCLPP was stratified by census tracts and matched with soil lead data.

The pre-and post-Katrina data sets of New Orleans
The lead dust in soil data from the City of New Orleans's (plus a small number of St. Bernard and Jefferson Parish residential communities) (census tracts, n=172) and the blood lead biomonitoring responses of children living in the same communities before and after Hurricane Katrina were compiled [12]. Pre-and ten years post-Hurricane

Natural vs. lead contaminated soil of New Orleans
The natural soils of New Orleans are derived from Mississippi River sediments. The sediments contain remarkably small amounts of lead, i.e. median of 5 (range 1-20) mg/kg [25]. The residential soils of New Orleans have become contaminated with lead dust sources from industrial emissions and consumer products. Few studies have scrutinized lead dust accumulated in urban soil and its influence on health, sustainability, and wellness at the scale of urban communities. The research conducted before and after Hurricane Katrina in New Orleans assists with filling the research gap by examining the association between lead dust in soil and children's blood lead responses [12,14,26].
The Mississippi River sediments are a massive resource of naturally low lead containing alluvial soil for landscape remediation of contaminated soil in New Orleans [27].

Reactive vs. proactive lead exposure intervention
The medical community faces a quandary. Pediatricians are required to test children's blood lead, although this requirement is inconsistent between states [28]. If blood lead levels are above CDC's reference value (currently 5 µg/dL and expected to decrease to 3.5 µg/dL soon) then the prescription involves educating the parents about sources of lead exposure and an inspection that focuses on lead-based paint and household dust cleaning. The dilemma for the medical community concerns reports that the prescribed lead intervention is in ineffective. For example, when states with well-established household lead cleanup program are compared with states without a household cleanup program no difference is observed in the children's exposure outcomes [29].
The critical gap involves the reactive handling of children's elevated lead exposure and the subsequent intervention methods used to treat elevated exposure. Cochrane Collaboration is a world-renowned, expert authority for evaluating the effectiveness of medical interventions. The past two evaluations by Cochrane Collaboration concluded that the prescribed lead intervention is ineffective at reducing the blood lead of exposed children [9,10]. If an intervention is not effective then the healthcare community must do the research needed to modify the intervention [30].

Conclusions
Pharmacology studies the chemistry of life and researches ways to support wellness. In New Orleans life expectancy is observed to be higher (77-80 years) in other communities and lowest (55-58 years) in inner-city communities.
Environmental signaling researches the associations between chemicals in the exterior milieu and their influence on wellness. At the scale of New Orleans's communities, a strong association is evident between lead in the exterior environment and children's biomarkers of lead. Lead exposure during early childhood is recognized clinically as having lifelong and multiple negative health influences on morbidity and wellness. Hurricane Katrina flooded 80% of New Orleans, and 10 years after the event both soil lead and blood lead underwent a notable decrease. The massive nearby reservoir of low lead alluvial soil presents the feasibility to reduce lead exposure in New Orleans through a community-scale landscaping.

Acknowledgements
Special thanks to Trina Williams, MPH (ScD Candidate), and Dr. Ngoc Huynh, MD, Louisiana Healthy Homes and Childhood Lead Poisoning Prevention Program (LHHCLPPP) for compiling the blood lead data for this project.
Grants for the ten year post-Katrina soil survey were contributed by the Ling and Ronald Cheng Fund matched by private funding sources. The Department of Pharmacology provided steadfast support. Finally, "Environmental Signaling" owes its existence to discussions and encouragement by colleague and friend, Professor John A.

Conflicts of Interest Statement
The authors declare that they have no conflicts of interest concerning this manuscript.