Pollard 1998 Protocol
Definition
The standardised diatom test protocol published in Forensic Science International by A.M. Pollard (1998), specifying acid digestion conditions, wash steps, microscopy method, and blank contamination controls.
- Author
- A.M. Pollard
- Year
- 1998
- Journal
- Forensic Science International
- Field
- Diatom test for drowning
- Covers
- Acid digestion, wash steps, microscopy, blank controls
Common questions
Why do blank contamination controls matter so much in the diatom test?+
Diatoms are ubiquitous in laboratory water, reagents, and airborne dust, so without a properly run blank alongside the tissue sample a positive diatom finding cannot be reliably attributed to the water body the victim drowned in rather than to laboratory contamination.
What does standardizing the acid digestion step achieve?+
Consistent digestion conditions destroy the organic tissue matrix while leaving the silica diatom frustules intact, and standardizing this step across laboratories is what makes diatom counts and species comparisons between cases and reference water samples meaningful.
Related terms
- Diatom Test
- A laboratory test for ante-mortem submersion in which bone marrow (from sealed femur diaphysis) is acid-digested and the diatom species identified in...
- Dry Drowning
- Drowning in which laryngospasm seals the glottis, preventing water entry into the lungs. The victim asphyxiates without pulmonary aspiration. Autopsy shows non-specific...
- Frustule
- The silica cell wall of a diatom, composed of two overlapping valves (epitheca and hypotheca). Frustules are taxonomically distinctive, chemically resistant to...
- Secondary Drowning
- Death from delayed non-cardiogenic pulmonary oedema occurring hours to days after an immersion and aspiration event, even if the victim was apparently...
- Vitreous Sodium
- The sodium concentration in the vitreous humour of the eye; reduced below normal in freshwater drowning (systemic haemodilution) and elevated in saltwater...
- Washerwoman Hands
- White, wrinkled, macerated skin on the hands and feet from prolonged water immersion. Indicates duration of immersion, not ante-mortem versus post-mortem submersion.
- Wet Drowning
- Drowning in which water is aspirated into the airways and lungs during the immersion event. Produces over-distended pale lungs, frothy exudate, and...