Predicting the Fate of Pesticides in the Environment

Concentration vs Sampling Dates (actual data) in 0 - 7.5 cm Soil Samples

Health Canada requires the development of data to predict the fate of pesticides in the environment and to substantiate the physiochemical, mobility and biotransformation data from laboratory studies. Field studies, conducted under representative soil or aquatic conditions, are mandatory to support final Canadian registration.

Calibration, Application & Documentation

VARS specializes in this particular type of study. After study plan approval and site selection, the test substance arrives and is stored in our temperature monitored storage facility. Application of the pesticide is made after careful calibration of the spray equipment. Documentation of the calibration procedures, such as nozzle flow rate measurement, are a routine part of this process. Actual pass times over the treated plots, the actual volumes applied and all environmental conditions are promptly recorded in the field notebook. Plots are then ready for sampling.

Sampling

We currently use a hydraulic soil core probe capable of sampling down to 122 cm. Typically, the top portion of soil is removed with a large diameter probe. The remaining soil profile is removed using a smaller diameter probe which takes the sample from the same location without touching the soil surface.

The zero contamination sampling method reduces the chance of trace amounts of pesticide reaching the lower soil levels during the sampling procedure. Soil cores are frozen as soon as possible after sampling, usually within the hour.

Sample Processing & Shipping

Sample processing is also done at our facility. The cores are cut into 15 cm sections and composited according to depth. Samples may then be frozen in our temperature monitored walk-in freezer.

Shipping of frozen samples may take place on dry ice or with a freezer truck delivery service. Sample lists and chain of custody forms accompany all shipments. Laboratories are always notified of shipments on the day they leave our facility.

GLP, QA & SOP

Good Laboratory Practices Standards are followed at every stage in the study. Standard Operating Procedures (SOP) are maintained at our facility, along with the required logbooks on equipment. All activities are entered in a raw data field note book prepared for each study. Archives are maintained for personnel files, logbooks and raw data. Quality Assurance (QA) is available by our in-house QA unit.