Inhalation and dermal exposure to biocidal products during foam and spray applications.

OBJECTIVES: Foaming and spraying are common application techniques for biocidal products. In the past, inhalation and dermal exposure during spraying have been investigated extensively. Currently, however, no exposure data are available for foaming, hindering a reliable risk assessment for foam applications of biocidal products. The focus of this project was the quantification of inhalation and potential dermal exposure to non-volatile active substances during the foam application of biocidal products in occupational settings. In some settings, exposure during spray application was measured for comparative purposes. METHODS: The inhalation and dermal exposure of operators were investigated during the application of benzalkonium chlorides and pyrethroids by foaming and spraying, considering both small- and large-scale application devices. Inhalation exposure was measured by personal air sampling; potential dermal exposure was measured using coveralls and gloves. RESULTS: Potential dermal exposure was substantially higher than inhalation exposure. Changing from spraying to foaming reduced inhalation exposure to airborne non-volatile active substances, but had no relevant effect on potential dermal exposure. However, for potential dermal exposure, considerable differences were observed between the application device categories. CONCLUSIONS: To our knowledge, this study presents the first comparative exposure data for the foam and spray application of biocidal products in occupational settings with detailed contextual information. The results indicate a reduction of inhalation exposure with foam application compared to spray application. However, special attention is necessary for dermal exposure, which is not reduced by this intervention.

Aerosol formation during foam application of non-volatile biocidal substances.

The application of biocidal products by foam is considered an alternative to droplet spraying when disinfecting surfaces or fighting infestations. Inhalation exposure to aerosols containing the biocidal substances cannot be ruled out during foaming. In contrast to droplet spraying, very little is known about aerosol source strength during foaming. In this study, the formation of inhalable aerosols was quantified according to the aerosol release fractions of the active substance. The aerosol release fraction is defined as the mass of active substance transferred into inhalable airborne particles during foaming, normalised to the total amount of active substance released through the foam nozzle. Aerosol release fractions were measured in control chamber experiments where common foaming technologies were operated according to their typical conditions of use. These investigations include foams generated mechanically by actively mixing air with a foaming liquid as well as systems that use a blowing agent for foam formation. The values of the aerosol release fraction ranged from 3.4 × 10-6 to 5.7 × 10-3 (average values). For foaming processes based on mixing air and the foaming liquid, the release fractions could be correlated to the process and foam parameters such as foam exit velocity, nozzle dimensions, and foam expansion ratio.

Multiplexed Workplace Measurements in Biogas Plants Reveal Compositional Changes in Aerosol Properties.

Anaerobic digestion is an emerging technology producing energy from renewable resources or food waste. Exposure screenings, comprising hazardous substances and biological agents, at different workplaces are necessary for a comprehensive overview of potential hazards in order to assess the risk of employees in biogas plants. In order to analyse these parameters, workplace measurements were conducted in seven full-scale anaerobic digesters. Personal and stationary sampling was performed for inhalable and respirable particles, volatile organic compounds, ammonia, hydrogen sulphide, carbon monoxide, and carbon dioxide. Furthermore, concentrations of the total cell count, endotoxins, and fungi-down to species level-were determined in comparison to windward air. Sequencing of the 16S rRNA genes was utilized for the determination of the bacterial composition inside the biogas plants. Measurements of hazardous substances show hardly values reaching the specific occupational exposure limit value, except ammonia. An approximate 5-fold increase in the median of the total cell count, 15-fold in endotoxins, and 4-fold in fungi was monitored in the biogas plants compared with windward air. Specifying the comparison to selected workplaces showed the highest concentrations of these parameters for workplaces related to delivery and cleaning. Strikingly, the fungal composition drastically changed between windward air and burdened workplaces with an increase of Aspergillus species up to 250-fold and Penicillium species up to 400-fold. Sequence analyses of 16S rRNA genes revealed that many workplaces are dominated by the order of Bacillales or Lactobacillales, but many sequences were not assignable to known bacteria. Although significant changes inside the biogas plant compared with windward air were identified, that increase does not suggest stricter occupational safety measures at least when applying German policies. However, exposure to biological agents revealed wide ranges and specific workplace measurements should be conducted for risk assessment.

Inhalation and dermal exposure of workers during timber impregnation with creosote and subsequent processing of impregnated wood.

OBJECTIVES: Coal tar creosote oils are used as highly effective wood protectants for, e.g., railway sleepers, utility poles and marine pilings. For impregnation of wood, the hot creosote oil is mostly applied in vacuum processes and by hot-and-cold dipping. From the perspective of an occupational hygienist, creosote tar oils are problematic because they have a number of hazardous properties, including carcinogenicity. We have studied inhalation and dermal exposure in six and four impregnation plants, respectively, in Germany. Some plants were visited repeatedly, for up to five measurement campaigns conducted over several years. Inhalation and dermal exposure resulting from vacuum impregnation and from hot-and-cold dipping, as well as secondary exposure resulting from assembly of impregnated railway sleepers have been measured. Accompanying, human biomonitoring of the employees has been performed. METHODS: Inhalation exposure was measured using personal air samplers, collecting particles and vapours simultaneously. Dermal exposure was investigated by whole body dosimetry using disposable chemical protective coveralls and split leather gloves. 18 polycyclic aromatic hydrocarbons (PAHs) have been determined separately by high performance liquid chromatography (HPLC) or gas chromatography-mass spectrometry (GC-MS), respectively. For human biomonitoring 1-hydroxypyrene (1-OHP) in urine related to creatinine has been measured using HPLC. Both, pre- and post-shift values have been determined for this metabolite. RESULTS: Dermal exposure towards pyrene and the sum of the determined 18 PAHs as well as inhalation exposure to naphthalene, pyrene and the sum of the determined 18 PAHs are presented in this paper. The plants performing vacuum impregnation have employed different constructive, technical and organisational measures, and some measures have also changed between the different measurement campaigns. We have found that cooling the vacuum impregnation vessel before unloading can reduce inhalation exposure to about one-third. However, our data shows that installation of structural or technical risk management measures (RMM) did not always reduce the exposure as intended, and can even lead to increased exposure in adverse constellations. Dermal exposure was strongly affected by differences in the working procedures. Measurements performed during assembly of impregnated railway sleepers indicate that secondary exposure leads to lower inhalation, but similar dermal exposure compared to the impregnation processes. Also 1-OHP excretion rates are similar after impregnation process and after assembly of impregnated railway sleepers. CONCLUSION: Our recent data underlines that efficient reduction of the exposure resulting from impregnation with creosote requires sophisticated risk reduction strategies. Structural measures such as the enclosure of the loading area and technical measures like local exhaust ventilation shall be coordinated carefully with organisational measures and provision of personal protective equipment. The data presented here represents a broad bandwidth of current workplace situations in the creosote oil processing industry and is therefore suitable for risk assessment in related plants as well as under regulatory frameworks like the European Biocides Regulation. Each plant in this investigation was unique. Together they represent the whole width of this branch in Germany. Additionally, the number of plants and exposed workers is limited and relative low. Therefore, a comprehensive consideration and statistical analysis were not feasible.

Dermal and Inhalation Exposure of Workers during Control of Oak Processionary Moth (OPM) by Spray Applications.

BACKGROUND: The caterpillars of the oak processionary moth (OPM) form stinging hairs, which release an irritant poison. They cause skin and eye irritation and sometimes even breathing difficulties and allergic reactions. OPM is mainly controlled by spraying insecticides. Insecticides applied for protection of human health must be authorized under the Biocidal Products Regulation (BPR) (EU) No 528/2012. In order to assess safety of professional use, which is a key requirement for the authorization, a risk assessment based on exposure estimation has to be performed. However, no exposure data specific for OPM control was available until now. Existing models for agricultural spray applications such as Agricultural Operator Exposure Model cover different spray patterns and equipment and were therefore considered too unreliable for assessment of OPM control. METHODS: We have studied dermal and inhalation exposure of certified pest control operators resulting from spraying DimilinTM 80 WG suspensions with vehicle-mounted spraying (VMS) and with handheld spraying (HHS) devices for control of OPM. Exposure resulting from these applications, from weighing and portioning of the granular product and from cleaning of contaminated spraying devices was studied. Dermal exposure was investigated by whole body dosimetry using disposable chemical protective coveralls and cotton gloves as samplers. Inhalation exposure was measured using personal air samplers. The active substance diflubenzuron was quantified by gas chromatography-mass spectrometry with positive chemical ionization and by high-performance liquid chromatography for dermal and inhalation measurements, respectively. RESULTS: The exposure was dominated by the dermal pathway. HHS results in considerably higher operator exposure than VMS. Comparison with data from typical agricultural spraying applications revealed that OPM control results in much higher exposure of operators for both, vehicle-mounted and handheld equipment. CONCLUSIONS: Comprehensive data on potential dermal and inhalation exposure is presented in this article, along with typical figures for handled and applied amounts of product and respective task durations. This data is suitable for risk assessments in regulatory frameworks such as the European BPR.

Suitability of several naphthalene metabolites for their application in biomonitoring studies.

Naphthalene occurs together with polycyclic aromatic hydrocarbons (PAHs) at industrial workplaces and is ubiquitous in the environment. For biological monitoring of naphthalene exposures, up to now mainly 1- and 2-naphthol in urine have been used. Recently, we proposed 1,2-dihydroxynaphthalene (1,2-DHN) and the 1- and 2-naphthylmercapturic acid (1- and 2-NMA) as new urinary biomarkers to characterise a naphthalene exposure. In this study, in a collective of nine occupationally exposed workers handling with creosote the naphthalene metabolites 1,2-DHN, 1- and 2-NMA as well as 1- and 2-naphthol were analysed in order to evaluate the suitability of the different parameters for their application in biomonitoring studies. Additionally, air sampling was conducted to characterise the exposure in task related exposure situations at different workplaces. In the analysed 51 urine samples, 1,2-DHN was the main metabolite with concentrations ranging from 2.3 to 886 µg/g creatinine (crea) (median 34 µg/g crea). For the sum of 1- and 2-naphthol, concentrations in the range of 2.6-174 µg/g crea (median 15 µg/g crea) were observed. 1-NMA concentrations were in the range of < LOD-2.4 µg/g crea (61% > LOD), while 2-NMA was not detected in the analysed urine samples. The biomarkers 1,2-DHN, 1- and 2-naphthol as well as 1-NMA showed significant correlations, which pointed out to naphthalene as the common exposure source. The poor correlations between naphthalene in the air and the biomarkers in urine may be a result of the varying exposure situations and may indicate not solely inhalative, but additional dermal uptake. 1,2-DHN was the most sensitive and, together with 1-NMA, the most specific parameter of the biological monitoring of naphthalene exposure at workplaces. Further studies with this parameter are needed for individuals at different workplaces as well as for persons of the general population without occupational PAH exposure to characterise 1,2-DHN levels as well as to establish their relationship with the naphthalene exposure.