Occupational exposure, to inhalants

Immunological and Lymphoreticular Effects. Occupational exposures to inhaled formaldehyde, phenol and isomers of organic chlorohydrocarbons from Ksylamit which is a widely used liquid wood preservative, were associated with immunological effects such as decreased levels of CD4, suppressed mitogen-induced lymphocyte proliferation, and significantly decreased natural killer cell cytotoxicity. However, it should be noted that in the report Ksylamit is indicated to consist of a mixture of chlorinated benzenes, pentachlorophenol, alpha-chloronaphthalene, chloroparaffin and kerosene and that the authors provide no discussion of how phenol and formaldehyde are produced through the use of such a mixture (Baj et al. 1994). 

For similar routes and forms of mercury, the adverse health effects seen in children are similar to the effects seen in adults. For example, a young child who was intoxicated with mercury vapor, died of pulmonary edema and had a grayish, necrotic mucosa of the stomach and duodenum (Campbell 1948). These effects are similar to those seen in adult populations occupationally exposures to inhaled metallic mercury vapors. Respiratory effects in adults from inhalation of metallic mercury vapor include pulmonary edema, lobar pneumonia, fibrosis, desquamation of the bronchiolar epithelium, and death in severe cases due to respiratory failure (Gore and Harding 1987 Jaffe et al. 1983 Kanluen and Gottlieb 1991 Matthes et al. 1958 Taueg et al. 1992 Teng and Brennan 1959 Tennant et al. 1961). 

Occupational exposure to inhaled fluoride dusts in cryolite workers during aluminum refining has resulted in severe bone abnormalities, but safety equipment now limits such exposure. No cases of skeletal fluorosis are attributed to use of controlled fluoridation of water supplies. However, skeletal fluorosis may occur in areas of the world where naturally occurring drinking water has high levels of fluoride, such as China and the Indian subcontinent. It is thought that exposure to fluoride intakes of 10 to 25mg/day for 10 years or more may result in skeletal fluorosis, but other nutritional factors may make these populations more susceptible. ... 

In eomparative in vitro and in vivo studies, oil ash is typically more toxic than other ashes, and its toxieity is largely related to its high content of transition metals, particularly iron, nickel, and vanadium (63,67). Hauser et al. (68) reviewed the literature on short-term effects of exposure to oil ash among boiler workers and reported a new prospective study of the effects of working on oil boilers on respiratory function. Exposure to oil ash causes reduced function measured by spirometry, but no ehanges were observed in airway reactivity. There is little epidemiological information on the long-term effects of occupational exposures to inhaled oil ash. 

Occupational exposures to inhaled carbon black have been reported to cause bronchitis, pneumoconiosis, and emphysema however, this information is sketchy and derived more from case reports than from adequate epidemiologieal studies of morbidity (26). Epidemiological studies of workers suggest that heavy, prolonged exposures can cause reduced lung function, but there is little evidenee of debilitating pneumoconiosis from contemporary exposures (72). 

Health and Safety Factors. Malononitrile is usually available as a soHdifted melt in plastic-Hned dmms. Remelting has to be done carefully because spontaneous decomposition can occur at elevated temperatures, particularly above 100°C, in the presence of impurities such as alkaHes, ammonium, and 2inc salts. Melting should be carried out by means of a water bath and only shordy before use. Occupational exposure to malononitrile mainly occurs by inhalation of vapors and absorption through the skin. Malononitrile has a recommended workplace exposure limit of 8 mg/m, an LD q (oral, rats) of 13.9 mg/kg, and is classified as slight irritant (skin irritation, rabbits). Transport classification RID/ADR 61, IMDG-Code 6.1, lATA/ICAO 6.1. 

As stated earlier, inhalation is the main route of absorption for occupational exposure to chemicals. Absorption of gaseous substances depends on solubility ifi blood and tissues (as presented in Sections 2.3.3-2.3.5), blood flow, and pulmonary ventilation. Particle size has an important influence on the absorption of aerosols (see Sections 2.3.7 and 3.1.1). 

Most of the hterature reviewed concerning the health effects of endosulfan in humans described case reports of occupational exposure and accidental or intentional ingestion of endosulfan. The cases of occupational exposure to endosulfan concerned exposures of acute-to-intermediate durations, and the cases of oral exposure were exclusively acute-duration exposure situations. The predominant route of exposure in the occupational case reports is believed to be inhalation, but the possibility of some degree of dermal exposure cannot be ruled out. The information on human exposure is limited because the possibility of concurrent exposure to other pesticides or other toxic substances cannot be excluded. In addition, the precise duration and level of exposure to endosulfan generally cannot be quantified from the information presented in these reports. 

In studies designed to examine dermal absorption of trichloroethylene, emersion of the hand (Sato and Nakajima 1978) or thumb (Stewart and Dodd 1964) for 30 minutes was reported to be pairrful. The pain was described as excruciating in one study (Sato and Nakajima 1978), and in another study it was described as mild by one subject and moderately severe by two subjects (Stewart and Dodd 1964). Occupational exposure to trichloroethylene that involved both dermal and inhalation exposure has been reported to result in dizziness, headache, insomnia, lethargy, forgetfulness, and loss of feeling in the hands and feet (Bauer and Rabens 1974 Kohlmuller and Kochen 1994). 

Gastrointestinal Effects. Case reports indicate that acute inhalation exposure to trichloroethylene results in nausea and vomiting (Buxton and Hayward 1967 Clearfield 1970 David et al. 1989 DeFalque 1961 Gutch et al. 1965 Milby 1968). Anorexia, nausea, vomiting, and intolerance to fatty foods have also been reported after chronic occupational exposure to trichloroethylene (El Ghawabi et al. 1973 Schattner and Malnick 1990 Smith 1966). Trichloroethylene-induced efiects on the autonomic nervous system may contribute to these effects (Grandjean et al. 1955). Some of the people exposed to trichloroethylene and other chlorinated... 

Mineral Oil Hydraulic Fluids. Studies regarding cancer in humans or animals after inhalation exposure to mineral oil hydraulic fluids were limited to a single case-control study that examined associations between subjectively reported occupational exposure to petroleum-derived liquids and cancer at particular sites among 3,726 male cancer patients (Siemiatycki et al. 1987a). The study found no convincing associations between occupational exposure to hydraulic fluids and cancer at any site. This study is discussed in more detail in Section 2.2.3.8, because, while inhalation exposure was probable for the subject occupations, the authors reported that the exposure route was more often dermal contact. 

NIOSH. 1986. Acute and chronic respiratory effects of exposure to inhaled toxic agents. In Merchant JA, ed. Occupational respiratory diseases. Publication of the National Institute for Occupational Safety and Health, U.S. Department of Health and Human Services, 571-605. DHHS (NIOSH) publication no. 86-102. 

Deaths associated with occupational exposure to inorganic lead (which is predominantly by the inhalation route of exposure) are discussed in Section 2.2.1.1. No studies were located regarding death in animals after inhalation exposure to inorganic lead. 

Subsequently, individual data on exposure are converted to dose by using conversion factors (OECD/NEA, 1983). The choice of the appropriate numerical value depends on physiological parameters (e.g. respiratory minute volume) as well as physical characteristics of the inhaled aerosol (e.g. particle size). Mean values range typically from about 5 mSv/WLM (non-occupational exposure) to about 10 mSv/WLM (occupational exposure). 

Occupational exposures via inhalation of acrylonitrile vapor at the work place are likely to be considerably greater than exposures outside the workplace (Table 5-1). Exposure levels may be highest for workers in plants where the chemical is synthesized (EPA 1984). 

Clinical signs of peripheral neuropathy similar to those seen in human occupational exposures to w-hexane can be produced in rats via the inhalation and oral routes, but not in other test species (Altenkirch et al. 1982 De Martino et al. 1987 Dunnick et al. 1989 Frontali et al. 1981 Huang et al. 1989 IRDC 1981 Krasavage etal. 1980 NTP 1991 Schaumburg and Spencer 1976 Takeuchi etal. 1980). Paranodal axonal swelling in mice (Dunnick et al. 1989 NTP 1991) and leg weakness in chickens (Abou-Donia et al. 1985) can be produced with inhalation exposure to -hexane, but these conditions do not progress to the severe neurotoxicity observed in humans and rats. The molecular mechanism... 

Intermediate-Duration Exposure. Case studies of occupational exposure to 77-hexane by the inhalation route show that neurotoxicity can develop in humans over this duration period (Altenkirch et... 

---