<P> Blood alcohol content (BAC), also called blood alcohol concentration, blood ethanol concentration, or blood alcohol level, is most commonly used as a metric of alcohol intoxication for legal or medical purposes . </P> <P> Blood alcohol concentration is usually expressed as a percentage of ethanol in the blood in units of mass of alcohol per volume of blood or mass of alcohol per mass of blood, depending on the country . For instance, in North America a BAC of 0.1 (0.1% or one tenth of one percent) means that there are 0.10 g of alcohol for every dL of blood . </P> <Table> <Tr> <Th_colspan="3"> Progressive effects of alcohol </Th> </Tr> <Tr> <Th> BAC (% by vol .) </Th> <Th> Behavior </Th> <Th> Impairment </Th> </Tr> <Tr> <Td> 0.001--0.029 </Td> <Td> <Ul> <Li> Average individual appears normal </Li> </Ul> </Td> <Td> <Ul> <Li> Subtle effects that can be detected with special tests </Li> </Ul> </Td> </Tr> <Tr> <Td> 0.030--0.059 </Td> <Td> <Ul> <Li> Mild euphoria </Li> <Li> Relaxation </Li> <Li> Joyousness </Li> <Li> Talkativeness </Li> <Li> Decreased inhibition </Li> </Ul> </Td> <Td> <Ul> <Li> Concentration </Li> </Ul> </Td> </Tr> <Tr> <Td> 0.060--0.099 </Td> <Td> <Ul> <Li> Blunted feelings </Li> <Li> Reduced sensitivity to pain </Li> <Li> Euphoria </Li> <Li> Disinhibition </Li> <Li> Extraversion </Li> </Ul> </Td> <Td> <Ul> <Li> Reasoning </Li> <Li> Depth perception </Li> <Li> Peripheral vision </Li> <Li> Glare recovery </Li> </Ul> </Td> </Tr> <Tr> <Td> 0.100--0.199 </Td> <Td> <Ul> <Li> Over-expression </Li> <Li> Boisterousness </Li> <Li> Possibility of nausea and vomiting </Li> </Ul> </Td> <Td> <Ul> <Li> Reflexes </Li> <Li> Reaction time </Li> <Li> Gross motor control </Li> <Li> Staggering </Li> <Li> Slurred speech </Li> <Li> Temporary erectile dysfunction </Li> </Ul> </Td> </Tr> <Tr> <Td> 0.200--0.299 </Td> <Td> <Ul> <Li> Nausea </Li> <Li> Vomiting </Li> <Li> Emotional swings </Li> <Li> Anger or sadness </Li> <Li> Partial loss of understanding </Li> <Li> Impaired sensations </Li> <Li> Decreased libido </Li> <Li> Possibility of stupor </Li> </Ul> </Td> <Td> <Ul> <Li> Severe motor impairment </Li> <Li> Loss of consciousness </Li> <Li> Memory blackout </Li> </Ul> </Td> </Tr> <Tr> <Td> 0.300--0.399 </Td> <Td> <Ul> <Li> Stupor </Li> <Li> Central nervous system depression </Li> <Li> Loss of understanding </Li> <Li> Lapses in and out of consciousness </Li> <Li> Low possibility of death </Li> </Ul> </Td> <Td> <Ul> <Li> Bladder function </Li> <Li> Breathing </Li> <Li> Dysequilibrium </Li> <Li> Heart rate </Li> </Ul> </Td> </Tr> <Tr> <Td> 0.400--0.500 </Td> <Td> <Ul> <Li> Severe central nervous system depression </Li> <Li> Coma </Li> <Li> Possibility of death </Li> </Ul> </Td> <Td> <Ul> <Li> Breathing </Li> <Li> Heart rate </Li> <Li> Positional alcohol nystagmus </Li> </Ul> </Td> </Tr> <Tr> <Td>> 0.50 </Td> <Td> <Ul> <Li> High possibility of death </Li> </Ul> </Td> </Tr> </Table> <Tr> <Th_colspan="3"> Progressive effects of alcohol </Th> </Tr>

What is considered a dangerous blood alcohol level
find me the text answering this question