## 1 Introduction  
Fungicide use is extensive in different environments such as industrial, agricultural, hospital and household. Its applications range from the protection of seed grain during storage, suppression of mildews that attack painted surfaces, control of slime in paper pulps to the protection of carpet and fabrics in the home, among others [1]. So important is fungicide use that ca. 500 million pounds of fungicides are applied worldwide annually [1]. The term fungicide refers to either chemicals or biological agents that inhibit the growth of fungi or fungal spores [2]. Over time, numerous substances employed as fungicides have a wide and diverse chemical structural spectrum, covering both inorganic and organic substances [3]. Some of the earliest fungicides were inorganic materials such as sulfur, lime, copper and mercury compounds [4]. However, many countries have been withdrawn some of the inorganic metallic fungicides, especially mercurous compounds, due to their high toxicity and adverse environmental effects [3]. This fact does not only focus on inorganic fungicides but also organic fungicides are under review. For example, vinclozolin has been removed from use for damage to human health and several fungicides are known to cause developmental toxicity and oncogenesis [2; 4]. Today, the main role of modern fungicides is the inhibition of fungi growth and/or fungal spores (i.e., they do not kill fungi). To reduce the toxicity of fungicides, the new routes consist of finding alternatives from natural resources. When the term fungus is defined, several classes are included as yeast, mold, and fungi. In a household environment, the presence of mold is a serious problem. Large quantities of mold spores can be a risk to the health of humans, potentially causing allergic reactions and respiratory problems. Therefore, it is essential to keep buildings, like houses or hospitals, free of microorganisms, such as fungi and even bacteria, with antimicrobial agents that show low-toxicity for humans. Zinc pyrithione (ZnPT) is a broad-spectrum antimicrobial agent that works against the growth of bacteria, fungi, and mold. This agent is registered in the Food and Drug Administration (FDA) because of numerous applications, such as medical, scientific and industrial. The main applications of ZnPT are as a fungicide in anti-dandruff shampoos, anti-fouling agents for boats [5], or it is also included in textiles [6], adhesives, paints [7], etc. Despite the antimicrobial advantages of ZnPT, there are doubts about its potential toxicity. ZnPT shows high toxicity to aquatic plants and animals such as algae, invertebrates, crustaceans, and fishes [8; 9]. Likewise, some studies report the potential penetration of ZnPT in human epidermis, causing cell damage [10; 11]. European Union carries out periodic reviews about the recommended concentrations of ZnPT not to be harmful to human health [7]. Therefore, there is no clear certainty about the cytotoxicity absence of ZnPT. In addition, ZnPT can easily photodegrade via direct photolysis under solar irradiation [12]. This photochemical degradation of ZnPT can modify its properties and activity, not allowing antimicrobial effectiveness in areas exposed to light. Given the background here mentioned, zinc oxide is posed as an antimicrobial agent alternative in agreement with the new idea of looking for materials from natural resources. Zinc is a bio element necessary for life in small quantities in living beings. The oxide form, ZnO, is found in nature as the zincite mineral, although the vast majority of ZnO is produced synthetically. The antimicrobial response of ZnO is widely reported, both for bacteria and fungi [13; 14; 15; 16; 17; 18; 19; 20; 21]. Most researchers correlate the antimicrobial activity of ZnO with the particle size, being more effective in the nanometric scale [22; 23; 24]. More specifically for fungi, [PERSON] et al.