In humans, oxalic acid has an oral (lowest published lethal dose) of 600 mg/kg (human).

The main toxicity of oxalic acid is due to the precipitation of calcium oxalate in the kidneys when urine becomes supersaturated with respect to this salt. Oxalic acid is also a metabolism product of the degradation of ethylene glycol if accidentally ingested and, as such, directly represents a danger for the kidneys in case of glycol poisoning.

First Aid
IF SWALLOWED -Give 1 or 2 glasses of water and call for medical assistance immediately.
EYE CONTACT - Wash with plenty of water for at least 15 minutes; Get medical attention promptly.

Paraffin wax is mostly found as a white, odorless, tasteless, waxy solid, with a typical melting point between about 46 and 68 °C (115 and 154 °F), and a density of around 900 kg/m3. It is insoluble in water, but soluble in ether, benzene, and certain esters. Paraffin is unaffected by most common chemical reagents but burns readily. Its heat of combustion is 42 MJ/kg.

Paraffin wax is an excellent electrical insulator, with a resistivity of between 1013 and 1017 ohm metre.  This is better than nearly all other materials except some plastics (notably Teflon). It is an effective neutron moderator and was used in James Chadwick's 1932 experiments to identify the neutron.

Paraffin wax is an excellent material for storing heat, with a specific heat capacity of 2.14–2.9 J g−1 K−1 (joules per gram kelvin) and a heat of fusion of 200–220 J g−1.  Paraffin wax phase-change cooling coupled with retractable radiators was used to cool the electronics of the Lunar Roving Vehicle during the manned missions to the Moon in the early 1970s.  Wax expands considerably when it melts and this allows its use in wax element thermostats for industrial, domestic and, particularly, automobile purposes.