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Factors That Can Affect Your Blood Alcohol Concentration

Because blood alcohol concentration (BAC) is often positively correlated with a driver’s degree of impairment, a drunk driving suspect’s blood alcohol concentration reading taken at or shortly after the time of their arrest is likely to become a key piece of evidence in their driving under the influence (DUI) case. In Virginia, anyone who tests at a BAC of .08% or higher can be charged with DUI. Most adults know that BAC is influenced by how much alcohol the individual has recently consumed. However, certain other factors can also affect BAC. Drivers should be aware of these factors and be careful to avoid driving when factors are present that might push them over the legal limit. If you have recently been charged with DUI in Virginia, the experienced Virginia DUI defense lawyers at Driving Defense Law may be able to help. Contact us today at (757) 929-0335 to discuss your case in a free consultation.

What Is Blood Alcohol Concentration (BAC)?

Blood alcohol concentration (BAC) is a measure of the percentage of alcohol in someone’s bloodstream. For example, a BAC of .10% would mean that the person’s bloodstream consists of one part of alcohol for every 1000 parts of blood.

When we consume alcohol, our stomachs and small intestines absorb it into the bloodstream. Alcohol is toxic, which means that our livers metabolize it to filter it out of our bloodstream. When someone drinks at a rate faster than the liver’s rate of metabolization, their BAC increases, and the person becomes intoxicated. According to the Cleveland Clinic, healthy livers can generally process approximately one alcoholic beverage per hour if there are no other factors present that might slow the removal of alcohol from the bloodstream. 

What Factors Can Affect BAC?

Understanding BAC is pivotal for responsible alcohol use. Numerous factors can influence BAC levels and how alcohol affects our bodies. Some of these factors may be more common than many people realize. Lack of awareness can lead to unanticipated degrees of impairment, often with devastating consequences.

Rate of Alcohol Consumption

The speed at which alcohol is consumed influences our BAC more than anything else. Rapid drinking raises BAC levels more quickly than moderate consumption over an extended period. The type of alcohol also matters – spirits tend to have a more immediate effect on BAC compared to beer or wine due to their higher alcohol content. A healthy liver not affected by other chemical factors may be able to metabolize one drink per hour, but people enjoying a beverage do not always pace themselves to a single drink, sipped evenly over the course of an hour.

Most Recent Meal

The amount of food in a drinker’s stomach can have a significant impact on their BAC. The BAC of someone drinking on an empty stomach will increase more quickly than that of someone with a full stomach. Conversely, having a meal shortly before drinking, or enjoying one’s beverage alongside a meal, can help to slow the rate of alcohol absorption and result in a lower BAC. 

Gender Differences

Essentially, blood alcohol concentration is a way of conceptualizing the amount of blood circulating in an individual’s body that is actually made up of alcohol at a specific moment in time. Painting in very broad strokes, the average woman is smaller than the average man, and the average man has more total blood circulating in his body compared to the average woman. 

One implication of these statistical differences in body size and composition is that women, on average, have less water in their bodies to dilute the alcohol they consume than their male counterparts do, so women will typically have a higher BAC when drinking the same amount of alcohol as a man. A simple way of illustrating this basic concept is to observe that a pint of beer is significantly larger in proportion to a person who weighs 150 pounds than it is in proportion to a person who weighs 250 pounds. 

Psychological and Emotional State

Psychological factors like stress, anxiety, and anger can amplify the effects of alcohol and may lead to higher BAC levels through their effects on the body’s metabolic processes. Stress emotions can impact stomach enzymes, which can influence how a person absorbs and processes alcohol. In addition, psychological factors that dysregulate the operations of the central nervous system (CNS) may exacerbate the impairments experienced by individuals drinking even modest amounts of alcohol. 

Individual Factors

Genetics may also play a role in how our bodies process alcohol. Enzymes involved in the absorption and breaking down of alcohol vary from person to person, which results in variations in BAC levels even among individuals of similar size who have drunk the same types and quantities of alcohol beverages. Personal alcohol tolerance levels, which are typically developed over time with regular alcohol consumption, may also significantly impact blood alcohol concentration.

Medications can also interact with alcohol, in some cases affecting how it breaks down and resulting in an elevated BAC. Understanding how any medications you are taking interact with alcohol is vital to avoid these adverse effects. 

Are Breathalyzer Tests Always Accurate Indicators of BAC?

Most DUI arrests are made based on a breathalyzer reading of over .08%. Although breathalyzers often provide an accurate reading of a suspect’s BAC, various factors can result in an erroneous reading and a false DUI arrest. If you were arrested for DUI and suspect that your charges may have been based on inaccurate results from a breathalyzer test, you may be able to learn more about your legal options by contacting Driving Defense Law’s Virginia DUI defense lawyers.

Medical Conditions

Certain medical conditions may distort breathalyzer readings, regardless of alcohol consumption. Conditions like acid reflux, diabetes, and other gastrointestinal disorders may cause inaccurately high BAC readings on breathalyzer tests, which could potentially result in an erroneous DUI charge. 

Breathalyzers typically measure alcohol content in the linings of the lungs, and the deepest lung air provides the most accurate BAC reading. However, for individuals with some gastrointestinal disorders, alcohol can move from the stomach to the throat, potentially leading to an inflated and inaccurate BAC reading. Even for individuals without these health conditions, eating a meal that causes acid reflux can skew BAC results due to the presence of acid in the breath or mouth.

Chemical Compounds

Breathalyzer devices do not directly measure alcohol. They measure the methyl group of chemical compounds, often assuming that the presence of such compounds is ethyl alcohol. However, various compounds can trigger a false positive if they are present in the breath at the time the test is administered:

  • Gasoline, paint, and propane fumes
  • Acetone in the breath of diabetics or those with low-carb diets
  • “Mouth alcohol” from burping, dentures, oral diseases, vomiting, mouthwash, medications, lip balm, inhalants, tobacco, and certain foods.

Test Administration Errors

In Virginia, police officers are required to use breath test devices approved by the Virginia Department of Forensic Science and to follow established protocols when administering breathalyzer tests. These devices must be regularly and properly maintained and calibrated to ensure accurate readings. Police officers also require proper training in how to accurately administer breathalyzer tests. Failure to follow any of these requirements could potentially result in an inaccurate BAC reading. 

Learn More From Our Virginia DUI Defense Lawyers

Understanding the factors that affect blood alcohol concentration levels is vital for responsible drinking and avoiding DUI charges. If you have recently been charged with DUI, you have legal rights. A Virginia DUI defense lawyer may be able to review your case and help you evaluate the best course of action based on the circumstances. Options may include fighting the charges in court, working towards getting them dismissed without trial, or reaching a plea agreement with the prosecution. Contact Driving Defense Law today at (757) 929-0335 to learn more about your legal rights after being charged with DUI in Virginia.