This manual describes the use of the transfer model to estimate the concentration of several organochlorine pesticides in egg yolk fat of the laying hen based on oral exposure to feed contaminated with these pesticides. The pesticides included in this model are dieldrin, hexachlorobenzene (HCB), alpha-hexachlorocyclohexane (alpha-HCH), beta-hexachlorocyclohexane (beta-HCH), gamma-hexachlorocyclohexane (gamma-HCH; lindane), heptachlor and dichlorodiphenyltrichloroethane (DDT).  The model has several input fields (left side) and output fields (right side). The input and results can be saved using the button “Report (*.docx)”. Source information and a citation suggestion are provided (top).

Step 1: Compound

The user needs to select one of the pesticides from the drop down menu. The pesticides included in this model are dieldrin, HCB, alpha-HCH, beta-HCH, gamma-HCH (lindane), beta-heptachlor epoxide (beta-HCE, metabolite of heptachlor) and total dichloordifenyltrichloorethaan (total DDT, the sum of DDT and its metabolite dichlorodiphenyldichloroethylene, DDE).

Step 2: Contamination level of feed

The user needs to provide the contamination level of the selected pesticide in feed (expressed in mg/kg feed) in the contamination field.

Step 3: Feed intake

The user first has to select the type of feed that is contaminated with the selected pesticide.

a)    This can either be:

• Total compound feed (blend of various raw materials and additives)
• Compound feed ingredients

When compound feed ingredients are selected, a drop down menu will appear to select the contaminated compound feed ingredient.

b)    After selecting the contaminated feed (ingredient), a default feed intake value is provided (in kg 88% dry matter per day) for the laying hen¹. The user can adjust this default value to the value corresponding to the actual feeding regime.

Step 4: Exposure period of laying hen to contaminated feed

To estimate the concentration of the selected pesticide in egg yolk fat, the user has to enter the duration of the exposure of the animals to the contaminated feed and the time elapsed after exposure, if applicable (both expressed in days).

Step 5: Regulatory limit (optional)

A regulatory limit (for instance maximum level) (expressed in mg/g egg yolk fat) for the selected pesticide can be inserted. The selected limit will be plotted in the output graph as a red line.

Step 6: Running model

The “Run model” button, present at the bottom of the input fields, can be used to run the model. After changing a value in any of the input fields, the “Run model” button has to be used to update the results.

Step 7: Results

After running the model the results will appear in the output field. The graph displays the concentration of the selected pesticide in egg yolk fat (in mg/g egg yolk fat) as a solid black line.

Several tools for viewing the graphs become visible on the right top of the graphs when hoovering anywhere in the graphs. For example, the option ‘show closest data on hoover’ will display the exact x and y-values when hoovering the plotted result. 

Step 8: Saving input and output

Using the “Report (*.docx)” button, present at the bottom of the input fields, input data and the results of the model run can be stored locally as a report file in word. Input data and results are not stored at the website.

Step 9: Citation suggestion

At the top of the model page the references that describe the model are listed, as well as a citation suggestion. Please use the suggested citation when referring to the model.

 ¹ Van Raamsdonk LWD, Kan CA, Meijer GAL, Kemme PA (2007) Key figures for some farm animals and their consumption patterns [in Dutch]; https://research.wur.nl/en/publications/kengetallen-van-enkele-landbouwhuisdieren-en-hun-consumptiepatron.