Long Questions 1 Discuss basic arguments in favor and against traditional approaches to risk assessment What are the basic science policy assumptions used to apply animal and or human studies for assessing risk Do these science policy assumptions tend to underestimate or overestimate risks Is risk assessment and the use of animal evidence too conservative or not protective enough of public health Tomatis Gold readings and lectures Arguments against traditional approaches to risk assessment lack accuracy and completeness when evaluating managing the risks of emerging technologies or new pollutants Lack of data forces assumptions In terms of Hazard ID exposures need to be high to show a relationship However most people are exposed to low levels traditional approach to risk assessment have difficulties in accurately assessing cancer risks due to low level exposure to multiple carcinogens Argument in favor of traditional approaches to risk assessment Using animal carcinogenesis data with information on the prevalence and levels of human exposures to estimate cancer risk could be useful when human data is absence o provide reliable information on the capacity of an agent to produce cancer in mammalian systems and to contribute to decisions that would lead to better protection of human health in the absence of contrary mechanistic information it is reasonable to assume a linear dose response relationship carcinogenesis usually have a linear dose response curve Science policy assumptions for animal human studies for assessing risk Hazard ID o Animal evidence is relevant to predicting human risks o Humans respond like most sensitive test species Dose response o Linearity at low doses for cancer no threshold o Risks due to exposures to several chemicals are additive no synergistic effects Science policy assumptions tend to overestimate risks It assumes Humans respond like the most sensitive test species Extrapolation of high dose animal data to typical low level human exposure o Bioassays require administration of doses that are higher than typical chronic doses that humans experience High dose effects due to experimental conditions that cause disease in a way that would not happen outside the lab High doses overwhelm the body s capacity of self repair High dose mechanism irrelevant at low doses Risk assessment and the use of animal evidence are too conservative Linear assumption cancer risk estimates for toxin control programs are worst case hypothetical estimates and the true risks at low dose are often likely to be zero 3 Discuss the unique issues related to children s environmental health What is meant scientifically when researchers say that children are not little adults Why are children uniquely vulnerable to environmental hazards and why are we concerned about in utero exposures particularly to endocrine disrupting compounds Use an example of mercury lead an endocrine disrupting compound or another hazard to back up your arguments Lectures and readings by DiRenzo et al Schettler et al introduction Lead and mercury have been the most extensively studied reproductive and developmental toxicants They are widely dispersed throughout the environment and everyone is exposed to them Not little adults Child are not little adults because they need healthy environments in which to grow and develop play and learn Children often have different and unique exposures to environmental hazards from those of adults Strong evidence suggests that lead exposure leads to subtle neurological effects developmental delays and behavioral abnormalities Children have a longer life expectancy they have longer to manifest a disease with a long latency period and longer to live with toxic damage Children are vulnerable to environmental hazards Toxic chemicals enter the environment through food and energy production industrial emissions and accidents waste transportation and the making use and the making use and disposal of consumer and personal care products As children grow at a much faster rate than adults consume more food and water and more likely to put things in their mouths They are more likely to be exposed to toxics One study that tracked down women who had been lead poisoned as children forty years before and asked them about their reproductive history found a 60 increase in risk of spontaneous abortion It suggests that early lead exposures may affect subsequent reproductive ability Evidence shows that the in utero environment is a critical bridge to future health Example Utero exposure outcomes Example Lead has long term effects on behavior and intelligence in infants born to mothers with blood levels of 10 25ug dl Developmental delays in lead exposed children persist at least until five years of age One study followed children into adulthood and found a sevenfold increased risk of non graduating from high school and a sixfold increased risk for reading disability in children exposed to lead as baby 4 Identify some of the historical influences that have driven global population trends over the last 100 years or so both growth and decline of fertility and population numbers Discuss the issue of population dynamics in terms of two of the following questions In the past decade population has been slower than previously estimated Population Division reports that the current annual growth of about 78 million people in the world s population is about 12 million fewer than previously estimated The annual world population growth fell from 2 percent in 1970 to 1 17 percent in 2005 Is population growth a problem Why or why not Yes it is a problem Population increases and rising per capita consumption levels are leading to environmental degradation and resource depletion at an unsustainable pace The world s economy are currently overshooting the Earth s capacity to regenerate natural resources The infrastructure of most cities in developing countries cannot keep pace with such rapid and sustained urban population growth In some countries where population is growing rapidly and efficient technologies to protect the environment are lacking there is little choice but to exploit natural resources to accommodate people s needs What is the connection between population consumption technology and social inequality In other countries despite slower population growth and more efficient technologies standards of living are so high that the population treads heavily upon nature When consumption levels are high even slow