Thesis (Ph. D.)--University of Rhode Island, 2005. / Typescript. Includes bibliographical references (leaves 120-131).

Thesis (M.S.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains vii, 83 p. : ill. (some col.), col. maps. Includes abstract. Includes bibliographical references.

Thesis (M. Sc.)--University of Hong Kong, 1997. / Includes bibliographical references (leaf 92-95).

Please read the abstract in the section 00front of this document / Dissertation (MSc)--University of Pretoria, 2005. / School of Health Systems and Public Health (SHSPH) / Unrestricted

Thirty years since the removal of lead from gasoline, lead still poses a health risk. Children are most at-risk for adverse health outcomes caused by lead toxicity due to both behavioural (e.g., hand-to-mouth behaviour) and physiological differences (i.e., increased intake of lead by body weight, higher uptake rate and a higher vulnerability to the effects of lead) compared to adults (Yeoh et al., 2009). As a result, governments must identify children that may be at-risk of lead poisoning and develop practical methods to mitigate lead exposure. Before a government can develop a policy to help mitigate exposure of lead for children, we need to understand the spatial distribution of lead within the city. A popular spatial model used within air pollution research may allow more accurate, and more localized predictions than the most common interpolation method, kriging. Land use regression (LUR) is a technique leveraging multiple predictor variables to help estimate the spatial distribution of the dependent variable. By using historical sources of lead, LUR can be used to model soil lead levels (SLL) with localized variation. Unfortunately, spurious relationships can be the basis of a LUR model, which may lead to an overfitted spatial model resulting in a model with little generalizability and questionable ability to estimate the dependent variable at unobserved locations. Ultimately, Empirical Bayesian Kriging may be the best option for soil contamination research due to its ability to provide a smoothed prediction surface and its dependence on the spatial structure of the data to provide estimations. The benefit to society and the return on investment (ROI) is often the justification for lead remediation. Gould (2009) estimates a $17 to $221 ROI for every dollar spent on lead hazard control. One of the main components of this estimate of ROI comes from the decrease in intelligence quotient (IQ) that a child may experience as a consequence of lead toxicity. There are three main ways that a decrease in IQ can negatively impact the economy, (i) lower potential lifetime earnings, (ii) reduced tax revenues, and (iii) higher spending on special education (Gould, 2009). Since IQ has such a significant role in the ROI estimates, chapter 3 seeks to achieve a greater understanding of the relationship between blood lead levels (BLLs) and IQ. The loss of IQ points for an increase in blood lead concentration proposed by Lanphear et al. (2005) and referenced by Gould (2009) is significantly higher than what we found in our meta-analysis. Thus, the projected ROI proposed by Gould (2009) may be much lower than previously calculated. In the final chapter, the cost associated with permanent lead abatement is investigated based on ROI projections as a case study in Hamilton, Ontario. We show that, in most cases, permanent lead remediation is far too expensive for a municipal government. Furthermore, the capital initially invested may not be distributed back into the local economy, as the ROI suggests. We suggest that municipal governments make decisions based on need, rather than basing remediation decisions on ROI projections. Furthermore, we recommend the use of hazard quotient maps to help justify lead remediation as a more accurate representation of potential lead toxicity, instead of only looking at SLL exceedances across the city. / Dissertation / Doctor of Philosophy (PhD)

No description available.

Thesis (doctoral)--Munich, 1934. / Includes bibliographical references (p. 23-24).

Thesis (doctoral)--Munich, 1934. / Includes bibliographical references (p. 23-24).

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Environmental contamination along roadways with lead from processed petroleum and automotive residues has been reported. Toxicity to the herbivores grazing these areas has not been well studied. Comparison of lead concentrations adjacent to roads in Kuwait and in Oregon, USA was studied. Soil samples were taken from three sites at three different distances from the highway (0, 3 and 10 meters) adjacent to King Fahad Highway in Kuwait and Interstate 5 (I-5), Highway 34 (H-34) and Highway 20 (H-20) in Oregon. Soil was analyzed for lead concentrations. The mean lead concentrations in soil samples along King Fahad Highway were significantly higher (p<0.05) than those along 1-5, H-34 and 14-20 in Oregon [4943.6 ppm (mg/kg) vs 129 ppm, 94.9 and 81.67 ppm respectively]. In a field trial animal toxicity studies were conducted on sheep grazing near roadway in Kuwait and also in a controlled barn studies. Fifty lambs ranging in age from 4 to 9 months and grazing on Kuwait pasture adjacent to the King Fahad Highway were tested for blood lead. Levels were determined by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). Blood lead levels of these lambs ranged from 0.05-1.00 ppm. Only 12% of the tested population exceeded the blood lead above 0.1 ppm (the high normal value). None demonstrated any clinical signs of lead toxicosis. In addition, a controlled feeding trial was conducted with sheep ingesting similar concentrations of lead as were found along the roadways. These sheep were observed for clinical, gross and histopathological changes. Using the intensive lamb production system common in Kuwait, twenty five lambs ranging in age from 2-10 months were orally fed 0, 2, 4, 8 and 16 mg lead acetate/kg body weight/day in a controlled study. Blood lead levels were tested in these lambs at time zero, week two, and then at monthly intervals until the 14th week. All lambs were slaughtered and necropsied with select tissues analyzed for lead concentrations. Levels of lead in the blood were directly related to the daily administrated lead acetate (P<0.05). Neither gender, age nor breed of the sire had any affect on blood lead levels except for the 14th week where blood lead levels of the young lambs significantly exceeded (P<0.05) those in the older lambs with mean values of 0.54 and 0.34 ppm respectively. In general, lead levels in all the tested tissues were directly related to the amount of the daily oral administration of lead acetate. Differences between the tissue levels of lead in the experimental and control lambs (N=25) were statistically significant (P<0.05) in liver, bone and kidney but were not significant in trachea, testis, brain, diaphragm, ovary, lung, muscle, rumen, aorta, spleen, tongue, eye, intestine, heart and esophagus. Lead accumulation was the highest in bone at the lower ingested lead concentrations, but was the highest in the kidney at higher lead dosages. Lead values were significantly greater (P<0.05) in the livers of female lambs compared to those of the male. Bone, liver and kidney of the young lambs had significantly higher (P<0.05) levels of lead than older lambs with means of 19.24, 7.31 and 54.54 compared to 6.34, 3.59 and 21.31 ppm respectively. Gross lesions were not found in any of the 25 necropsied lambs. Histopathological changes of intranuclear inclusion bodies were found in 100% of the kidneys in lambs administered 8 mg/Kg/day and above and in 50% of the livers of the lambs administered the same dosages. Thirty three per cent of lambs administered 2 and 4 mg/kg/day had intranuclear inclusion bodies in their kidney but not in the liver. The controls had no inclusion bodies in any of these matching tissues. No clinical signs of lead toxicosis were observed in any lambs during the 14 weeks of the experiment. The same lamb population was used to compare blood lead levels and the growth performance of lambs (feed intake, weight gain and feed conversion) in relation to different dosages of lead acetate. Although there was a tendency for lambs ingesting the two higher lead doses to eat less feed, gain less weight; and have a lower feed conversion ratio, these differences were not statistically significant (P>0.05). The conclusion of these studies reveal some concern. Levels of lead as found near the highways of Kuwait were high enough to cause elevated tissue lead concentrations, particularly in liver and kidney, of lambs grazing adjacent to these highways. These levels cause tissue abnormalities in lambs and could be hazardous to human health eating the internal organs of these lambs. / Graduation date: 2000