SWS4550- Exam 3
The degree and mechanism of toxicity of a metal may depend on the route through which an individual is exposed. Which of these routes is most likely to be of most concern for Mn?
Inhalation
The cholera outbreak in the Kaniyambadi Harijan colony correlated loosely with rainfall events. What is the most likely explanation for this?
Rainwater carried the pathogen into water pipes
What is the Surface Treatment Rule?
Water utilities must provide systems to control waterborne diseases.
The Koppers site was primarily engaged in:
Wood treatment
Which of the following are environmental compartments through/to which a metal might be transported?
air/atmosphere; soil; sediment; water/snow; biota
The time from designation of Koppers as a Superfund site to the completion of remediation is:
over 30 years
Al is the third most abundant element in the Earth's crust, but may be toxic. Under what conditions might Al be considered to be of concern in soil?
pH less than 5.5
Aluminum is the third most abundant element in the Earth's crust, but may be toxic. Under what conditions might Al be considered to be of concern in soil?
pH less than 5.5
Which of the following is true about metal species?
-Affect how a metal will react with various media in the environment. -Affect environmnetal behavior and toxicity of a metal. -Defined as to isotopic composition, electronic or oxidation state, molecular structure, and phase.
Which of the following chemicals are considered the mostimportant for treatment at the Koppers site?
-Creosote and benzo(a)pyrene -Dioxin -Arsenic
The Clean Water Act deals largely with point source pollution. Which of the following would be considered point source?
-Effluent from a waste water treatment plant -Effluent from a factory
Nanomaterials:
-Include natural materials (e.g., viruses, volcanic ash, and the ultrafine fraction of soil solids) as well as man-made materials -Have high reactivity owing to extensive (very large) specific surface and a very large percentage of surface bound atoms
Which of the following would be regarded as part of an exposure route? Check all that apply.
-Inhalation -Ingestion
Which of these statements describes the linear multistage model? Check all that apply.
-Model of choice for the EPA -At low doses, the slope of the dose response curve is used to estimate lifetime risk -Modeled by a series of equations
Which of the following statements best describes the probit model? Check all that apply.
-More accurate for acute toxicity rather than chronic toxicity -Typically predict the lowest risk. -Fundamentally probabilistic; based on tolerance to carcinogens in large populations
Mixtures of some metals may have very different types of interaction, depending on the state of the metals. Examples of this are the different types of toxicological effects that Se may have on As toxicity and residence in the body. Which of the following effects have been noted for As in the presence of Se?
-Se may increase excretion of As -Arsenite may decrease the protective effects of Se, depending on the form of Se. -Se may promote the activities of antioxidant enzymes, which may protect against As damage.
Microbial RA differs from chemical RA in many ways, including which of the following?
-Secondary transmission, while often important in microbial RA, is not considered in chemical RA -There is nothing analogous to NOAEL in microbial RA
The U shaped curve in Fig. 1 suggests that:
-The element is required in low concentrations, but becomes toxic at high concentrations. -At low concentrations, there is increased risk of insufficient concentrations. -At high levels of concentrations there is an increasing risk of adverse effects.
What is the Safe Drinking Water Act?
-The principal federal law in the U.S. intended to ensure safe drinking water for the public
Which of the following would be regarded as part of an exposure pathway? Check all that apply.
-Transport of a toxic chemical into groundwater -Release of a toxic compound into surface water
Which of these are included in the basic steps of the risk assessment process? Check all that apply.
-risk characterization -exposure assessment -dose-response assessment -Hazard identification
The government relies on ? to set specific regulations:
Agencies such as the EPA
The EPA Regional Screening Levels for hazardous chemicals may change because:
Assumptions such as exposure or bioavailability may change based on new information.
Which of the following forms is typically considered to be the most toxic for Cr?
Cr(VI)
For the Koppers site, meeting an average SCTL for the entire site proved to be problematic because:
Even though the average for the entire property was below the SCTL, some areas were significantly higher than the SCTL.
Why does metal mobility in soil and sediment tend to increase as pH decreases?
Excess positively charged hydrogen ions compete for negatively charged soil and sediment surface sites.
Under what conditions might a relatively high risk (10-4) be acceptable? Check all that apply.
Exposure of relatively few people belonging to low risk category.
A non-threshold response to a chemical typically means that:
Exposure to even very low concentrations may not be tolerated.
Bioavailability of a given metal is constant for all sites, such that it is not necessary to consider bioavailability on a site by site basis.
False
In general, studies of cancer risk require very low numbers of test individuals studies if the risk is very low (1/10,000)
False
In general, the time between designation of a contaminated site as being eligible for designation as a Superfund site and completion of its clean up is approximately 1 year. Assume the Koppers site in Gainesville to be typical.
False
India is a democratic and egalitarian society, such that there is no segregation based on caste in villages. Everyone in the villages discussed here has equal access to clean water regardless of caste.
False
Knowledge of SCTLs are only important before beginning remediation.
False
Repeated exposure to diarrheal disease among young children is likely to be a good thing; they are less likely to develop problems such as environmental enteropathy in their later years because they have developed significant immunity.
False
Storm water runoff into surface water is considered to be an act of God and is not regulated by EPA.
False
The cholera outbreak in the Kaniyambadi Harijan colony correlated loosely with rainfall events. This is most likely due to the fact that cholera is an aquatic microorganism and grew dramatically with the addition of water to the environment through the rainfall.
False
The public has no opportunity to comment on a specific rule once it has been described in the US Code.
False
The target levels for remediation for Florida (Soil Cleanup Target Levels; SCTL) and the EPA (Regional Screening Levels; RSLs) for the priority chemicals at the Koppers site are similar.
False
The toxicological effects of mixtures of As and Cd are simply additive; the toxic effects of As are added to the toxic effects of Cd, and there is no interaction.
False
Total analytical concentrations measure only a single metal species.
False
At what stage in a risk assessment would you gather environmental samples to identify the presence of a possible hazard?
Hazard ID
RCRA provides "cradle to grave" management of:
Hazardous waste
What is the typical fate of Cr(VI) in the stomach?
It is reduced to a less toxic form
Consider the case where an individual is exposed to a carcinogen. It is assumed that in order for exposure to the chemical to result in cancer, a number of processes are assumed to occur: e.g., the chemical must pass through several processes, such as metabolism, bonding to DNA, repair of DNA, etc. Each of these events would decrease the probability of cancer. Which model would best describe this case?
Multistage
Consider the case where an individual is exposed to a single molecule of a strong carcinogen, with the result that DNA is damaged sufficiently to produce a malignancy. Which model would best describe that case?
One hit
What is the relationship between solubility and precipitation?
Precipitation occurs when a dissolved species exceeds the solubility limits of their solids.
What are the two general pools of metals in soil or sediment?
Reversibly bound or dissolved, and bound within mineral matrices
From Table 4, was the presence of a domesticated animal in the house a significant risk factor for diarrhea?
Rural
The de minimus principle is:
Some risks are so low that they are of no concern.
Natural soil concentrations of As may be higher than EPA screening levels. Why is this not a concern?
The As in water and diet is typically higher than that ingested via soil
The toxicity of a given metal may differ significantly between fresh and salt waters. Why?
The bioavailability of the metal may differ, with lower toxicity in salt than fresh.
The units of BCF are in terms of L Kg-1. Why?
The concentration is based on mg chemical/kg animal weight and concentration of chemical in water (mg/L).
The overall authority for protection of drinking water quality is given to:
The federal government
The US Code is:
The official record of all US laws.
In Table 4 of Kattula et al., what is the IRR?
The ratio of risk of a given factor (or practice) compared to its absence.
What is the Incidence Risk Ratio?
The ratio of risk of a given factor (or practice) compared to its absence.
The RfD is estimated by dividing the NOAEL by an uncertainty factor. The uncertainty factor is used because:
The relative sensitivity of individuals within a large population may vary
What is an advantage of a longitudinal study?
The same individuals are studied with time
What is the most likely pathway for cholera to enter the drinking water supply in the Kankyambadi Harijan colony?
The water supply pipes ran through the fecal field for the colony.
LOAEL may be used if no NOAEL is available; however, an uncertainty factor is frequently applied to it. Why?
To estimate the lowest no adverse effect level.
A major difference between MCL and MCLG is that MCL is achievable, and that MCLG may be desirable but not always achievable.
True
At low concentrations, some mixtures of metals may interact to decrease toxicity.
True
At low doses, the potency factor (PF) can be used to calculate the life time risk of a exposure to a chemical.
True
CERCLA assigns liability for cleanup of contaminated sites to the owners of the site, and includes taxes levied on producers and transporters of hazardous waste.
True
Compounds with relatively high PF and relatively low RfD are usually relatively toxic.
True
Exposure concentrations may rely on models because it may not be possible to monitor concentrations of a toxin or pathogen at all times.
True
In complexation, hard acids preferentially react with hard bases.
True
It was decided that the average SCTL for Koppers would be evaluated for each 5 acre parcel.
True
Regulatory agencies prefer to limit risk to below 1/100,000 for serious disease such as cancer.
True
Superfund is intended to provide money for the remediation of waste sites that pose a threat to human health. An example of a Superfund site in Gainesville is the Koppers site.
True
The Code of Federal Regulations lists most environmental regulations under Title 40.
True
The RfD is used specifically for chemicals that exhibit a threshold in toxicity.
True
The presence of siblings younger than 5 years old was a significant risk factor in both rural and urban samples, but more significant in rural.
True
With respect to metals particulates, aerodynamic size influences respiratory effects.
True
If dioxin is deposited on the soil from the air and its Koc is very high, would determining the concentration in the 0-6 cm depth likely over estimate or underestimate the risk of exposure to the surface soil?
Underestimate
From Table 2, was the incidence rate for diarrhea significantly greater in one area (rural versus urban) than the other?
Urban
For the Kattula et al. (2015) study, was a cross sectional or longitudinal study employed?
longitudinal
NOAEL is appropriate for:
non-carcinogens