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Improved estimates of water intake by mammals for risk assessment - PS2342

Description
Methods of estimating water intake in birds for risk assessment were reviewed in project PS2327. Current methods of estimating the drinking water requirements of birds were considered to be unsatisfactory as they do not take account of the water in the food so that a bird eating dry seeds would appear to have the same drinking water requirements as a bird feeding on leaves. It was recommended that drinking water estimates should be based on estimates of water influx rate (WIR) from doubly labelled water (DLW) studies combined with estimates of water in food and metabolic water production to calculate drinking water requirements. This provides a more realistic estimate of drinking water requirements than the existing method and is similar to the approach used for estimating daily energy expenditure (DEE) and food requirements in project PN0908.

It was recommended that where WIR estimates from studies on the species of concern are available, these should preferably be used in any risk assessment. Where WIR estimates for the species of concern are not available (which is the case for most UK species), estimates should be based on the appropriate allometric equation from Nagy and Peterson (1988), which allow predictions to be made for birds of different sizes and types (passerines, carnivores etc.). However, given the relative lack of actual measured WIR values for UK species, and the large number of DLW studies conducted since the late eighties when the existing allometric equations for water flux were developed, it was also recommended that these were updated to include this new information and this was done in project PS2330.

While we now have improved methods for birds, the current draft of the new mammals and birds guidance document (EFSA_GD_RA_birds_and_mammals_REV_CONSULTATION,0.pdf) highlights the need for improved estimates of drinking water estimates for mammals. The draft proposes the use of the estimates of Calder and Braun (1983) although allometric equations for water flux in mammals are available in Nagy and Peterson (1988) which could be combined with estimates of food water and metabolic water production as suggested for birds in project PS2327. However, project PS2327 also highlighted the need to update the estimates using data from doubly-labelled water (DLW) studies conducted since the late eighties and this was done for birds in project PS2330. The aim of this study is to update the data on water flux in mammals from DLW studies in the same way and use this to develop up to date allometric equations for water flux in mammals that can be used to estimate drinking water requirements. This will bring the method for mammals into line with the proposed method for birds in the current draft guidance document.

The aims of the project are to:

Collate data on water flux in mammals published since Nagy and Peterson (1988).

Use all available data to develop updated allometric equations for water flux in mammals.

Provide improved methods of estimating daily water intake by mammals for use in risk assessments as has been done for birds in project PS2330.

Present the above information to PSD in a form that can be of immediate use in risk assessments.
Objective
1. Collate data on water flux in mammals.

2. Use all available data to develop updated allometric equations for water flux in mammals.

3. Provide improved methods of estimating daily water intake by mammals for use in risk assessments as has been done for birds in project PS2330.

4. Present the above information to PSD in a form that can be of immediate use in risk assessments.

Project Documents
• Final Report : Improved estimates of water intake by mammals for risk assessment   (510k)
Time-Scale and Cost
From: 2008

To: 2008

Cost: £10,052
Contractor / Funded Organisations
Central Science Laboratory
Keywords
Agriculture and Food Chain              
Birds              
Crops              
Drinking Water              
Environmental Effects              
Habitats              
Indicators              
Mammals              
Pest and Weed Control              
Pesticide Residues              
Pesticide use              
Pesticides              
Plants and Animals              
Review              
Risk assessment and management              
Water              
Fields of Study
Pesticide Safety