The use of hand sanitizers is one of the most effective methods for infection control. Especially with the COVID-19 pandemic, these products have become widespread not only among healthcare workers but also in the general public [1][2]. To prevent the spread of infection, the World Health Organization (WHO) recommends frequent hand washing with soap or the use of hand sanitizers containing at least 60% alcohol [3]. Hand sanitizers recommended by the WHO and the Centers for Disease Control and Prevention (CDC) fundamentally contain different combinations of ethanol, isopropyl alcohol, n-propyl alcohol, and hydrogen peroxide [4]-[9]. However, the misuse of these products can lead to toxic effects on human health [3]. During the use of ethanol-based hand sanitizers (ABHS), a small amount of alcohol can be absorbed via the transdermal route and detected in the blood [1][4][7][8][10]. In addition to dermal contact during antisepsis, exposure to alcohol also occurs via the inhalation route [7][11][12]. In studies examining the effects of direct oral intake of alcohol on nasal functions, it has been shown that alcohol creates edema in the nasal mucosa and increases nasal resistance through a peripheral vasodilator effect and by suppressing catecholamine release in the central nervous system [13][14].

Although the literature contains studies demonstrating the negative effects of systemic alcohol use on nasal functions, there is no study investigating the effects of alcohol exposure via skin and inhalation due to ABHS and cologne use on nasal functions. Therefore, the aim of our study is to investigate the effects of ABHS and cologne, used to prevent the spread of infections, on blood alcohol level and nasal functions.

This study was conducted with the approval of the Atatürk University Faculty of Medicine Research and Training Hospital Ethics Committee. A total of 60 volunteer healthcare workers, over 18 years old, with a mean age of 27.5, and comprised of 33.3% female and 66.7% male participants, were included in the study. Participants were informed about the study and provided written consent. Individuals with allergies to hand sanitizer or cologne, chronic sinusitis or allergic rhinitis, or those who were pregnant or suspected of pregnancy were excluded.

Volunteers were divided into three groups:

1. Group: Hand sanitizer users (n = 20)

2. Group: Cologne users (n = 20)

3. Group: Control group (n = 20)

Participants were instructed to abstain from alcohol-containing food, perfume, and sprays for at least 12 hours before and during the study. In the first group, Poviexin (hand and skin antiseptic, contains:70 % ethyl alcohol, CAS No:64-17-5, glycerin and colorant) hand sanitizer containing 70% ethanol was used approximately 25 times at about 2 mL during an eight-hour working period. After applying the product to the hands, it was rubbed until dry. To prevent inhalation, it was ensured that the product was applied at least 30 cm away from the nose. In the second group, cologne containing 70% ethanol was used 25 times. Participants sprayed a total of 2 mL of cologne onto their right and left hands, rubbed their hands, and finally sniffed the product.

Venous blood samples were taken from both groups twice: before and after the application. Additionally, the VAS questionnaire, endoscopic examination, rhinomanometry, saccharin test, and nasal culture were performed. In the control group, the same evaluations were performed at the end of the eight-hour period.

No significant difference was found in age and sex distribution among the three groups included in the study (p > 0.05).

During hand antisepsis, healthcare workers may be exposed to various alcohols through inhalation and skin contact [7]. The frequent use of alcohol-based solutions in the hospital environment raises concerns among healthcare workers regarding the systemic effects of alcohol [9][15]. Intensive use of these preparations can pose a potential risk [4]. Clinically toxic effects of alcohol are headache, blurred vision, nausea, vomiting, abdominal pain, lethargy and hypotony [5][16]. On the other hand, frequent use of hand sanitizer can cause local skin problems such as skin damage and chronic contact dermatitis [17][18]. In our study was not observed any skin adverse effects. This is likely due to the glycerin content in the hand sanitizer, which acts as a moisturizer.

It is known that blood alcohol levels vary among individuals depending on sex, body weight, and the amount of alcohol consumed [13]. Previous studies have reported that alcohol used for disinfection is partially absorbed, can be detected in the blood, and may show toxic effects. Vivier et al. reported the development of toxicity in a 21-day-old infant whose mother used 70% isopropyl alcohol for umbilical dressing [16][19]. However, no toxic effect was observed in the participants in our study despite the use of hand sanitizer and cologne.

Different views exist in the literature regarding the effect of alcohol exposure on serum levels. Kramer et al. found small, dose-dependent increases in blood alcohol levels after the use of hand- sanitizers containing three different concentrations of ethanol (95%, 85%, and 55%) [9]. Brown et al. also reported that a low amount of ethanol could be detected in the serum with intense and repeated use of hand-sanitizers containing 70% ethanol and isopropanol. However, they did not specify whether this increase was via the transdermal or inhalation route [20]. Other studies have also reported an increase in blood levels after topical application, emphasizing that the inhalation route cannot be excluded [21]-[23]. In our study, an increase in serum ethanol levels was found after the use of both hand sanitizer and cologne. However, the increase in the cologne group was not statistically significant when compared to the control group. The higher serum ethanol levels found in hand sanitizer users may be attributed to the higher alcohol content in the products used. In some studies, no increase in serum alcohol levels has been reported after transdermal or inhalation exposure. Brugnone et al. have not detected isopropanol in the blood of paint workers after isopropanol exposure but found it in the exhaled breath, explaining this with a large volume of distribution [24]. Hautemaniere et al. have not detected alcohol in the blood and urine of healthcare personnel working with hand-sanitizers containing 70% ethanol [11]. Similarly, Ahmed-Lecheheb et al. have not found alcohol in the blood and urine of 86 healthcare workers after using ethanol- containing hand-sanitizers [4]. Miller et al. also stated that there was no increase in serum levels with four hours of intensive use of a hand-sanitizers containing 62% ethanol [25]. The finding of an increase in our study, contrary to these studies, may be explained by the long duration of exposure and the high alcohol content.

Some publications state that ethanol in alcohol-based solutions is mainly absorbed by inhalation, and transdermal absorption is limited [26]-[28]. Kirschner and Lang reported no transdermal absorption in randomized double-blind studies [8][15]. Conversely, Turner et al. showed that isopropyl alcohol could be absorbed through healthy human skin [29]. In our study, serum ethanol levels were found to be lower in the cologne group compared to the hand sanitizer group, despite sniffing the product after rubbing the hands. This is likely related to the variability in the ethanol content of cologne. Berkkan et al. found the ethanol content in 19 different colognes to be between 37% and 98% in their study during the pandemic [30]. Furthermore, as our study was conducted under pandemic conditions, the volunteers' use of masks may have limited the absorption of cologne via inhalation.

Inhaled alcohols are rapidly distributed due to their high solubility and increase swelling and resistance in the nasal mucosa by suppressing sympathetic activity through a depressant effect on the central nervous system [11][13][14][31]. However, no significant change in total nasal resistance measured by rhinomanometry was found after the use of either hand sanitizer or cologne in our study. This result suggests that exposure via the skin and inhalation is not as effective as alcohol consumption via the oral route. The fact that the obtained values remained within the limits considered normal in the literature shows that alchol-based hand sanitizers and cologne do not pathologically affect nasal resistance [31].

The increased VAS scores in the hand sanitizer group can be explained by the psychological effect due to the irritating odor of the chemical components in the products. The lack of change in VAS scores in the cologne group may be attributed to the pleasant scent, which does not create a negative perception. The inconsistency between VAS and endoscopic scores and the objective measurement of rhinomanometry has also been previously reported in the literature [32][33].

Mucociliary clearance is the primary defense mechanism of the airway and can be practically measured with the saccharine test [34]-[36]. Animal studies have reported reduced mucus transport at high alcohol levels, while effects in humans are variable [37]-[39]. In our study, although a prolongation in the group-specific mucociliary clearance time was observed in hand sanitizer users, no significant difference was found compared to the control group. In the cologne group, although the time was prolonged, it did not reach the pathological limit [40]. These results suggest that neither product impairs mucociliary function at a clinically significant level.

Nasal flora plays an important role in infection control. Staphylococcus aureus, which is part of the normal flora, carries the risk of nosocomial infection due to its carriage in healthcare workers [41][42]. In our study, S. aureus carriage was found to be 35%, which is consistent with the literature. The reduction in bacterial colony count in nasal cultures by hand sanitizer and cologne is an indicator of their antiseptic effects. This finding is also supported by previous studies [43][44].

The protocol of 25 applications within an 8-hour period was designed to reflect intensive yet clinically realistic hand hygiene practice among healthcare workers. Observational studies have reported that healthcare workers experience approximately 20 - 100 hand hygiene opportunities per shift, depending on clinical setting and workload, with higher frequencies in intensive care and emergency units [45]-[47]. Accordingly, the selected frequency represents the upper range of routine clinical practice rather than an exaggerated exposure, allowing assessment of systemic and nasal effects under real-world intensive-use conditions and enhancing the external validity of the findings.

Use of alcohol-based hand sanitizer and cologne increases detectable serum ethanol levels and causes changes in some nasal parameters with short-term applications. However, these changes are not at a pathological level. It was concluded that alcohol-based hand sanitizers and cologne hold an important place in infection control due to their effect of reducing nasal bacterial colonization.

Written informed consent was obtained from all participants.

The study was approved by the Atatürk University Faculty of Medicine Ethics Committee.