Dissolved Lithium Concentrations and Texas Suicide Mortality Rates by William M Flanagan University of North Texas Department of Geography

Introduction Spatial distribution of suicide mortality rates in Texas counties, from 1980 – Spatial distribution of suicide mortality rates in Texas counties, from 1980 – Disease ecology conceptual framework. Disease ecology conceptual framework.

Suicide Statistics In US, 32,000 suicide deaths annually. In US, 32,000 suicide deaths annually. 11th leading causes of death in US. 11th leading causes of death in US. Texans ranked 37th in completed suicides in 2002 in US. Texans ranked 37th in completed suicides in 2002 in US.

Risk Predictors of Suicide Mortality Gender Gender Females 3x more likely than males to attempt suicide.Females 3x more likely than males to attempt suicide. Males complete suicide 4x more than females.Males complete suicide 4x more than females.

Risk Predictors of Suicide Mortality Race Race White males have highest suicide mortality rate.White males have highest suicide mortality rate. Minority females have the lowest.Minority females have the lowest.

Risk Predictors of Suicide Mortality Lithium Lithium Used in treating manic depressive illnessUsed in treating manic depressive illness Suicide, homicide, and forcible rapeSuicide, homicide, and forcible rape Continued lithium treatment is associated with reduced suicide riskContinued lithium treatment is associated with reduced suicide risk Dissolved lithium concentrations in groundwater may provide a protective function on suicide behavior and mortality.Dissolved lithium concentrations in groundwater may provide a protective function on suicide behavior and mortality.

Lithium Concentrations in Nature Associated with volcanism, may explain presence in many aquifers Associated with volcanism, may explain presence in many aquifers Many counties and cities in Texas rely on groundwater for their water needs. Many counties and cities in Texas rely on groundwater for their water needs. Nutritional uptake of lithium through common foods and vegetables. Nutritional uptake of lithium through common foods and vegetables.

Hypotheses Gender is a predictor of suicide mortality. Gender is a predictor of suicide mortality. Race is a predictor of suicide mortality. Race is a predictor of suicide mortality. County suicide mortality rates will be influenced by dissolved lithium concentrations in the groundwater. County suicide mortality rates will be influenced by dissolved lithium concentrations in the groundwater. Suicide mortality rates are changing through time. Suicide mortality rates are changing through time.

Data Sources Age adjusted mortality data (1980 – 1998) Texas Department of Health’s Vital Statistics Division. Age adjusted mortality data (1980 – 1998) Texas Department of Health’s Vital Statistics Division. Population and other data from the 2000 US Census. Population and other data from the 2000 US Census. Dissolved lithium concentration data from Texas Water Development Board Groundwater Database Dissolved lithium concentration data from Texas Water Development Board Groundwater Database

Methodology Spearman’s 2-tailed Rank Correlation Spearman’s 2-tailed Rank Correlation Wilcoxon Two Sample Test Wilcoxon Two Sample Test

GENDER AND SUICIDE Males have a higher suicide rate than females (Z= , p=.000). Males have a higher suicide rate than females (Z= , p=.000). Males Average = 22.5 per 100,000 Females Average = 5.4 per 100,000

RACE AND SUICIDE Counties with higher % whites had higher suicide mortality (r=.315, p=.000). Counties with higher % whites had higher suicide mortality (r=.315, p=.000). Counties with higher % Hispanics have lower suicide mortality Counties with higher % Hispanics have lower suicide mortality (r= -.250, p=.000). No correlation between % African Americans and suicide mortality rates No correlation between % African Americans and suicide mortality rates (r= -.014, p=.827).

LITHIUM CONCENTRATIONS AND SUICIDE Dissolved lithium concentrations in groundwater is inversely related to suicide mortality rates (r= -.150, p=.017). Dissolved lithium concentrations in groundwater is inversely related to suicide mortality rates (r= -.150, p=.017).

TEMPORAL VARIATIONS OF SUICIDE Suicide mortality rates ( ) are lower than (Z = , p=.019).

CONCLUSIONS Male suicide rates are significantly higher than female suicide mortality rates Male suicide rates are significantly higher than female suicide mortality rates % Whites is positively correlation to suicide mortality rates % Whites is positively correlation to suicide mortality rates % Hispanics account for a negative correlation to suicide mortality rates. % Hispanics account for a negative correlation to suicide mortality rates. Counties with lower rates of dissolved lithium concentrations in groundwater have higher suicide rates Counties with lower rates of dissolved lithium concentrations in groundwater have higher suicide rates Suicide mortality rates are increasing with time. Suicide mortality rates are increasing with time.

SUGGESTIONS FOR FURTHER RESEARCH Intra-county variations ignored Intra-county variations ignored Other water sources (e.g surface and tap water) must be addressed. Other water sources (e.g surface and tap water) must be addressed. Finer geographical scale required. Finer geographical scale required. How the underlying geology affects lithium concentrations. How the underlying geology affects lithium concentrations.

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