Christine Andrews¹, Margit Kempf2, Roy Kimble3, Leila Cuttle4

1 Centre for Children’s Burns and Trauma Research, The University of Queensland, Centre for Child Health Research, South Brisbane, Queensland, 4101. c.andrews@uq.edu.au
2 Centre for Children’s Burns and Trauma Research, The University of Queensland, Centre for Child Health Research, South Brisbane, Queensland, 4101. kempfm@uq.edu.au
3 Centre for Children’s Burns and Trauma Research, Children’s Health Queensland, Lady Cilento Children’s Hospital, South Brisbane, Queensland 4101. royk@uq.edu.au
4 Centre for Children’s Burns and Trauma Research, Queensland University of Technology, Institute of Health and Biomedical Innovation at Centre for Children’s Health Research, South Brisbane, Queensland, 4101. leila.cuttle@qut.edu.au

Introduction
Despite legislation, many hot water taps in Australian homes deliver water at greater than 50⁰C. Clinicians are often required to provide ‘expert opinion’ regarding the heat dose (temperature and duration) required to cause deep partial thickness immersion injuries.
Methods
A porcine scald model was used to examine a range of burn conditions, from 50 to 60⁰C water, for 5 seconds to 10 minutes duration. Eleven juvenile pigs were used. Wound examination, biopsies and Laser Doppler Imaging were performed at 1, 24 hours and at 3 and 7 days post-burn. A subset of burns were followed for 21 days to observe wound healing.
Results
Histologically, significantly deeper dermal damage was observed for 55°C compared to 50°C water for 1 to 5 minute scalds (p < 0.001). Exposure to 50°C water for ≥ 10 minutes caused a deep dermal burn, 55°C water for ≥ 2 minutes produced an equivalent injury. By day 7, 60°C for 5 seconds showed no histological evidence of damage, whereas 60°C for ≥ 30 seconds showed tissue injury in the deep dermis. By day 21, 60°C for ≥ 1 minute scalds were still un-reepithelialised.
Conclusions
Novel scientific evidence for medicolegal use regarding the heat dose required to sustain a deep partial thickness immersion scald is presented. Importantly, quantitative histological data is translated to the clinically relevant outcome of time to healing. Compliance with hot tap water regulation is vital as a 5°C increase (from 50°C to 55°C) reduces the time taken to sustain a severe deep dermal burn from ≥ 10 minutes to only 2 minutes.

Key Words
Scald burns, burn depth, hot tap water safety, immersion scalds