Hydraulic fluids toxicity

FLUOROTRIAZINES Riag-fluoriaated triaziaes are used ia fiber-reactive dyes. Perfluoroalkyl triaziaes are offered commercially as mass spectral markers and have been iatensively evaluated for elastomer and hydraulic fluid appHcations. Physical properties of representative fluorotriaziaes are listed ia Table 13. Toxicity data are available. For cyanuric fluoride, LD g =3.1 ppm for 4 h (iahalatioa, rat) and 160 mg/kg (skin, rabbit) (127). 

PCBs and PCTs are particularly troublesome liquids because of their toxicity and persistence in the environment. They are defined as polychlorinated biphenyls, polychlorinated terphenyls, monomethyl-dibromo-diphenyl metliane, monomethyl-dichloro-diphenyl metliane or monomethyl-tetrachlorodiphenyl methane. With low electrical conductivity and heat resistance they found wide use as dielectric fluids and were formerly used as hydraulic fluids. PCBs have not been made in the UK since 1977 and whilst most new uses for the substance are banned in most countries, around two-thirds of the 1.5 million tonnes manufactured in Europe and the US prior to 1985 still remain in equipment such as transformers. PCTs have been used in the past in a restricted range of specialist industrial applications. 

The primary purpose of this chapter is to provide public health officials, physicians, toxicologists, and other interested individuals and groups with an overall perspective of the toxicology of hydraulic fluids. It contains descriptions and evaluations of toxicological studies and epidemiological investigations and provides conclusions, where possible, on the relevance of toxicity and toxicokinetic data to public health. 

The number of organophosphate esters and similar compounds used in hydraulic fluids is considerable. A core number (approximately 10) have been studied to some degree for toxicity. Though many hydraulic... 

In a series of acute lethality studies on U.S. military fluids, single gavage doses (4,250 or 5,000 mg/kg) of one of several polyalphaolefin hydraulic fluids did not produce signs of neurological toxicity in rats within... 

Tricresyl phosphate (a complex mixture containing tri-o, Xn-m-, and tri-para-cresyl phosphate that is used in certain hydraulic fluids) and TOCP are demonstrated testicular toxicants in rodents (Carlton et al. 1987 Somkuti et al. 1987a, 1987b). Tricresyl phosphate also has been shown to impair in vivo fertility in rats and mice (Carlton et al. 1987 Chapin et al. 1988a). In addition, tricresyl phosphate-treated female rats displayed vacuolar cytoplasmic alteration of ovarian interstitial cells (Carlton et al. 1987 NTP 1994). Reproductive effects have also been seen after oral exposure to butylated triphenyl phosphate (Latendresse et al. 1994b). 

No NOAELs or LOAELs were identified for toxic effects in humans after inhalation exposure to organophosphate ester hydraulic fluids. Reliable NOAELs and LOAELs for acute inhalation exposure are restricted to 4-hour NOAELs for systemic effects in rats exposed to Fyrquel 220 or Durad MP280 and 4-hour LOAELs for mild lethargy in rats exposed to Durad MP280 and Fyrquel 220 (Gaworski et al. 1986). The study identifying these NOAEL and LOAEL values did not measure cholinesterase inhibition, did not allow sufficient follow-up time for the development of delayed neurotoxic effects, and used a... 

Reliable NOAELs and LOAELs for intermediate oral exposure are restricted to a 90-day NOAEL of 50 mg/kg/day for systemic toxicity in rats (a species that is not sensitive to the neuropathic effects of organophosphate esters) exposed to Pydraul 90E for 90 days and NOAELs and LOAELs for delayed neuropathy in chickens exposed to Durad 110. In chickens exposed to Durad 110 for 28 days, a NOAEL of444 mg/kg/day and LOAEL of 1,333 mg/kg/day were identified (FMC 1986) when the duration was increased to 90 days, the NOAEL was 20 mg/kg/day and the LOAEL was 90 mg/kg/day (FMC 1986). These data are inadequate for derivation of an intermediate oral MRL for organophosphate ester hydraulic fluids. As discussed under the acute-duration oral MRL section, there is uncertainty regarding extrapolation of chicken doses to human doses. 

Toxicity data are available for several organophosphate ester components of hydraulic fluids, in particular tricresyl phosphate (NTP 1994). However, these components are always present in products as mixtures with other chemicals. Since insufficient information exists to assess the effect on toxicity of interactions among these mixtures, MRLs for the components were not derived. 

No data were located regarding toxic effects in humans following inhalation exposure to polyalphaolefin hydraulic fluids. Three of nine tested polyalphaolefin hydraulic fluids were lethal in rats at 4-hour aerosol concentrations ranging from <5,330 to <10,720 mg/m3. LC50 values for the three lethal fluids in females ranged from 1,390 to 1,670 mg/m3. Deaths were associated with respiratory irritation. The data are inadequate for acute inhalation MRL derivation. No intermediate or chronic inhalation MRLs for polyalphaolefin hydraulic fluids were derived due to the lack of data. 

Acute lethality studies in animals exposed by inhalation, ingestion, or dermal contact to several mineral oil hydraulic fluids indicate that mineral oil fluids are not potent toxicants. Mineral oil hydraulic fluids produced no deaths in rats after 4-hour exposures to aerosol concentrations of 110-210 mg/m3 or gavage administration of single doses <5,000 mg/kg (Kinkead et al. 1987a, 1988). Rabbits, likewise, did not die after single 24-hour exposures to occluded dermal doses of several mineral oil hydraulic fluids <2,000 mg/kg (Kinkead et al. 1985, 1987a, 1988). 

Mineral Oil Hydraulic Fluids. No human studies examining dermal end points were located. In animals, no information on dermal effects following inhalation or oral exposure were located. A number of mineral oil hydraulic fluids have been tested for acute dermal toxicity in rabbits. Signs of skin irritation have been observed following application of a naphthenic petroleum-based hydraulic fluid designated as MIL-H-5606... 

Data concerning developmental toxicity in animals are very limited, and are at best suggestive that elicitation of developmental effects by some organophosphate ester hydraulic fluids may occur in some animals. The developmental toxicity data are too sparse to make any conclusions regarding their relevance to human health. 

No information was located regarding populations that may be unusually susceptible to toxic effects produced by mineral oil hydraulic fluids or polyalphaolefin hydraulic fluids. 

This section will describe clinical practice and research concerning methods for reducing toxic effects of exposure to hydraulic fluids. However, because some of the treatments discussed may be experimental and unproven, this section should not be used as a guide for treatment of exposures to hydraulic fluids. When specific exposures have occurred, poison control centers and medical toxicologists should be consulted for medical advice. 

Mineral Oil Hydraulic Fluids. No specific methods were located for interfering with the mechanism of action for toxic effects produced by mineral oil hydraulic fluids. Unstable alveoli and distal airways have been proposed as major factors in the respiratory symptoms that occur after the ingestion of other petroleum-derived materials. Continuous positive airway pressure or continuous negative chest wall pressure, as well as the application of supplemental oxygen, have been recommended to counteract the resultant pneumonitis (Eade et al. 1974 Klein and Simon 1986). 

Polyalphaolefin Hydraulic Fluids. No specific methods were located for interfering with the mechanism of action for toxic effects produced by polyalphaolefin hydraulic fluids. 

Mineral Oil Hydraulic Fluids. There is limited information on the toxicity of mineral oil hydraulic fluids in humans. A single case report of a child accidentally ingesting a single dose of automotive transmission fluid provides limited information on death and systemic effects. A case-control study provides some information on the carcinogenicity of mineral oil hydraulic fluids. The study population was exposed via inhalation and dermal routes. An occupational exposure study provides information on neurotoxicity following chronic dermal exposure. Information on the toxicity of mineral oil hydraulic fluids is limited to a series of inhalation, oral, and dermal acute-duration exposures. These studies provide information on death, systemic effects, and neurotoxicity by inhalation, oral, and dermal routes, and immunotoxicity following dermal exposure. 

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