Biocides lindane

These relatively new biocides have a very low vapor pressure (tebuconazole 1.3 x 10 to 7.2 X 10 Pa, permethrine 1 x lO" to 4.5 x 10 Pa) compared to former biocides (lindane 1.2 x 10 to 9,4 x 10 Pa). Substances such as PCP, lindane or DDT are already found indoors in gaseous form or adsorbed to dust modem biocides such as pyrethroids are only found adsorbed to dust. 

Chlorinated micropoUutants are harmful for man and environment due to their toxicity, persistence, and bioaccumulation. Persistent compounds are very stable and difficult to get metabolized and mineralized by biological and chemical processes in the environment, and as a result, they have become ubiquitous in water, sediments, and the atmosphere bioaccumulation is the result of the lipophilicity of these compounds. Polychlorinated dibenzodioxins and -furans (PCDD/F) are not produced purposely like many of other chlorinated technical products, such as chlorinated biocides DDT, lindane, and toxaphene. The production and use of persistent organic pollutants (POPs), the dirty dozen has now been banned worldwide by the Stockholm protocol. It should be mentioned that about 3000 halogenated products have now been isolated as natural products in plants, microorganisms, and animals," but the total amount of these products is much smaller compared to xenobiotics. 

Biocides most often found in the indoor environment are chlorinated hydrocarbons like chlordane, DDT, dieldrin, lindane, heptachlor and methoxychlor, pyrethroids like cyfluthrin, cypermethrin, and permethrin, organophosphates like chlorpyrifos, diazinon, dichlorvos, isofenfos, and malathion, carbamates like ben-diocarb, carbaryl and propoxur and chlorophenols like pentachlorophenol (PCP), chlorocresol (4-chloro-3-methylphenol) and o-phenylphenol. Residues formed in house dust may vary in different countries (Butte, 2003), but biocides like chlorpyrifos, DDT, methoxychlor, permethrin, pentchlorophenol and propoxur seem to be the active compounds in biocide formulations even in different continents, as they are found equally in house dust samples form Germany and the USA (Becker et al., 2002 Butte, 2003 Camann, Colt and Zuniga, 2002). Concentrations of biocides in house dust are mostly in the milligram per kilogram range, they seldom exceed a microgram per cubic meter in indoor air. 

Concentrations of some biocides in the indoor environment show a tendency to decrease, others increase. According to the German environmental surveys (GerES), performed for nearly 20 years, concentrations of PCP in house dust are declining, a tendency already reported (Butte, 2003). On the other hand concentrations of lindane, piperonylbutoxide and permethrin seem to increase (Becker et al., 2002 Seifert et al., 2000). 

In the past, PCP, lindane and DDT have been used in several instances in Germany to protect wood indoors. In recent years modem biocides such as pyrethroids (e.g. permethrine) or triazoles (e.g. tebuconazole) have been used instead of the classical organic chloro-pesticides to protect wood. 

Biocides are either semivolatile or non-volatile organic compounds. Since vapor pressures of non-volatile biocides, e.g. pyrethroids, are small, these biocides are mainly particle-bound. Their analysis in air might not be appropriate for the detection of indoor contamination, and the investigation of household dust may be used alternatively. Other biocides are semivolatile, e.g. chlorpyrifos, lindane (y-HCH) and penta-chlorophenol indoor contamination may be detected by analyzing either air or dust. 

Typical concentrations for biocides in indoor air obtained under defined conditions either directly during or after application and up to 20 years after an incident have been compiled by Pluschke (1996) and are given in Table 3.5-3. For non-volatile biocides, i.e. pyrethroids, base levels in indoor air are < 20 ng/m, and even for semivolatile biocides such as pentachlorophenol and lindane they are < 50 ng/m. ... 

Wood preservatives and agents against insects and fleas are used by more than two-thirds of the population thus their residues can be found in nearly every home. Only in two households (< 1 %) could no biocide or synergist be observed. On the other hand chlorpyriphos, propoxur and lindane were present in more than 10 %, PBO in more than 50 %, DDT, permethrin and methoxychlor in more than two-thirds and PCP in nearly every sample. Results regarding concentrations of biocides in household dust were confirmed by those obtained in Schleswig-Holstein (LANU, 1997), but information about the use of biocides indoors was not obtained for the latter study. 

For chlorpyrifos and lindane, no differences were observed between the dust of homes where biocides had been used ( users ) and dust without application of any biocide by the occupants ( non-users ). DDT, methoxychlor and PBO concentrations in the dust of users of insecticides were significantly higher than in that of non-users (see Fig. 3.5-2 for methoxychlor). Users of wood preservatives showed higher concentrations of PCP and users of biocides against insects and fleas showed higher concentrations of propoxur. 

Dust may be regarded as the ideal material for detection and identification of indoor biocides and any of their residues still existing. Commercial vacuum cleaners ean be used for taking samples. Analysis using the < 63-pm fraction of dust lead to results that are more reproducible than those for any other fraction. Reliable results are only obtained under equilibrium conditions in rooms therefore there should be no cleaning for at least one week before dust samples are taken. Since the Umweltsurveys and two case control studies published recently are based on representative samples for household du.st of the German population (especially PCP, lindane and pyrethroids), the assessment of results is possible by comparison with reference values. 

Ruh, C., I. Gebefuegi, and F. Korte. 1984. The indoor biocide pollution occurrence of pentachlorophenol and lindane in homes. Chem. Abstr. CA 104(10) 74030x. 

Schieweck et al. (2007) analyzed biocides in dust samples in different rooms of a museum. A distinction between old and fresh dust was made. While the age of old dust is unknown, fresh dust was defined as dust whose age is determined by the measurement planning and it is known exaetly, usually 1-2 weeks. The concentrations of pentachlorophenol (PCP) and lindane in a sample of old dust taken direetly firom a sculpture were exceptionally high with 117 and 14 pg g , respectively. In the fresh dust samples taken from the floor, considerably high concentration up to 30 for PCP and 5 pg g for lindane were also found, which probably resulted from the intensive treatment of the wooden sculpture for purposes of conservation. This result gave evidence for a possible exposure of museum staff and visitors. 

---