Does ‘Prison Napalm’ work? Measuring the cooling temperature of sugar solution burns in a porcine model

Abstract

Non-accidental scalds sustained with sugar solution are potentially devastating and often associated with assaults within prisons where they are commonly known as ‘Napalm’ attacks. However, little is known about the mechanism behind such injuries. Proposed explanations have included a higher initial temperature, increased viscosity compared to water and lower emissivity, although these have yet to be demonstrated in any experimental model. We therefore set out to measure the post-exposure cooling temperature of the dermis after exposure to different concentrations of boiled sugar solution in a dead porcine model.Dead pork belly tissue was pre-heated to human body temperature (36.3–38.4 °C). Five solutions with different concentrations of sugar (0, 250, 500, 1000 and 2000 g/L) were heated to boiling point using standard commercially available kettles and then poured directly onto the tissue. Intradermal temperatures of the dermis were measured at one-minute intervals for a duration of 10 min.At one-minute after exposure, average intradermal porcine temperatures were 46.7 °C, 47.9 °C, 48.9 °C, 50.8 °C and 51.7 °C respectively for increasing concentrations of sugar solution. The rate of cooling was similar in all solutions with an average loss of 1.5 °C per minute. Using a generalised mixed model accounting for concentration and time period, it was identified that increasing sugar concentration resulted in statistically higher temperatures of burn (p = 0.006).Our report finds that higher concentrations of boiled sugar solution caused a higher initial temperature of burn but did not influence cooling rates. This suggests that ‘Prison Napalm’ attacks will indeed cause more severe burns than those utilising plain water, but not for all the widely believed reasons. We therefore recommend that access to kettles in prison cells should be limited, but where such access is deemed a right, consideration should be given to temperature restricted devices, as is the case in other countries.