TABLE 1.
Factors influencing the occurrence of bacteria/viruses/molds in laundry
| Factor(s) | Description | Reference(s) |
|---|---|---|
| Fabric composition | Thickness, material, coloring agents; the thicker the fabric, the greater the survival of bacteria during laundering; greater survival of coliforms in hand/face towels after laundering and drying | S. K. Tamimi, S. L. Maxwell, L. Sifuentes, and C. P. Gerba, unpublished data; Gerba, unpublished |
| Storage conditions | Bacterial no. increases in hampers and if stored under high humidity (molds and total bacterial no.); we have found that clothing stored in hampers between laundering can result in the growth of bacteria in clothing | Kennedy and Gerba, unpublished |
| Usage | Location on body where worn (higher no. on undergarments and in pockets than on shirts; face and kitchen towels have higher no.); length of time worn; highest no. of enteric bacteria found in face towels and underwear (e.g., coliforms) | 10; Gerba et al., unpublished |
| Season | Higher no. of bacteria during summer (mold); warmer weather and perspiration encourage growth of bacteria | K. A. Reynolds and C. P. Gerba, unpublished data |
| Age of clothing | Possibility of biofilm buildup; microorganisms adapt to repeated washing conditions and are not always removed | Reynolds Gerba, unpublished |
| Type of detergent | Additives to enhance detergent performance, i.e., enzymes and multiple surfactants | Reynolds and Gerba, unpublished |
| Dirt load | Type and quantity affect the performance of detergent and bleach | Kennedy and Gerba, unpublished |
| Wash temp and time | Greater survival of microbes at lower temp | 45, 62; Kennedy and Gerba, unpublished |
| Drying temp and time | Greater survival at lower temp and shorter length of drying time | 45; Kennedy and Gerba, unpublished |
| Air drying | Bacterial no. may increase in the clothing under humid outdoor conditions; prolonged exposure to sunlight may decrease no. of fungi | 13 |
| Type of microorganism | Resistance of microorganisms to washing varies with species and strain of microorganism; Mycobacterium, Enterobacter, and enteric viruses are more resistant to release from textiles and removal | 13, 45; Kennedy and Gerba, unpublished |
| Concn of microorganisms in bodily excretions or secretions | Enteric viruses and bacteria can be excreted in high concn in feces; Salmonella occurrence at concn as high as 1010 bacteria/g and norovirus occurrence at concn as high as 1011 particles/g of feces | 63 |
| Concn of bodily excretions or secretions in clothing | The avg pair of adult underwear contains an avg of 0.1 g of feces | 63 |
| Method of washing | Machine washing versus handwashing; no data found on handwashing but expected to be less efficient | 3 |
| Quality of wash water | In developing countries, fecally contaminated water may be used, such as in streams | 39 |