Preliminary Data Collection

Before conducting a risk assessment a number of preparatory steps are required. Two of the most important steps are:

  1. To choose data quality objectives
  2. To gather data

Data Quality Objectives (DQO)

Data Quality Objectives provide criteria for developing a data collection design that includes: when to collect samples, where to collect samples, the maximum allowable error for the study, and how many samples to collect. Using the DQO process will help ensure that the type, quantity, and quality of environmental data used in the risk assessment and/or risk management is appropriate. In addition, the DQO process will help prevent the collection of unnecessary data (USDOE 2008). For more information on DQO’s please visit: the US Department of Energy's Data Quality Objectives website.

Data Gathering

Before starting the risk assessment process, certain types of data will be required. Common tasks are as follows: 

Collection of pre-existing data - if previous investigations have been done at the site, some of the required data may be available as printed material. Other information, such as former site use may be available in the historical literature.

Conduct a site investigation - In addition to printed material, a site investigation is always recommended (Environment Canada 2003, USEPA 2008). By visiting the site, the Risk Assessor can collect current information which may not be available in the printed literature. A site investigation provides the risk assessor with data necessary to carry out a risk assessment. Information can include:

1) Visual Observations – i.e., What might be the contaminant of concern? What organisms might be exposed? How might organisms be exposed? Are there areas where soils appear to be darker or oily, or of a different color?

2) Collection of Samples For Analysis – i.e., What are the average and maximum concentrations of contaminants in exposure media (i.e., soils, sediments, water or tissue etc.)? Are there unexpected contaminants of concern? What is the spatial distribution of contaminants?

Collect Ancilliary Data - Ancilliary data includes data that can be used for the risk assessment, but is generally not collected during the site investigation. Ancilliary data can include the results of interviews of people on site - i.e., What are the human behaviors at the site which might result in exposure? Have effects been observed? What is the duration or frequency of exposure?

More information will be provided regarding data in the next sections.


Soil Sampling in Vientiane, Lao PDR
Source: Hatfield Consultants
Hatfield Consultants The World Bank funded by the Canadian POPs Trust Fund through the      
Canadian International Development Agency
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