Spacecraft Water Exposure Guidelines for Selected Contaminants Volume 2 (2007) / Chapter Skim
Currently Skimming:
Appendix 7 Formaldehyde
Appendix 7 Formaldehyde
Pages 300-341
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 300... ...
In addition to these numerous commercial TABLE 7-1 Physical and Chemical Properties Formula HCHO Synonym methanal, formic aldehyde, methyl aldehyde CAS registry no. 50-00-0 H Molecular weight 30.0 19.5oC | Boiling point 92 oC Melting point C=O Water solubility 55 g/100 mL | Vapor pressure 10 mm Hg at 88°C H Vapor density 1.08 Specific gravity 0.81 at 20°C 0.35 Log Kow Source: Data from ATDSR 1999.
|
From page 301... ...
. Once present in the air, the high water solubility of formaldehyde relative to its vapor pressure (a relationship expressed by its Henry's law constant)
|
From page 302... ...
As with any chemical, a thorough understanding of its absorption, metabolism, distribution, and elimination is crucial to gaining a perspective on its toxicity and to the setting of appropriate spacecraft water exposure guidelines (SWEGs)
|
From page 303... ...
. Upon metabolism from formaldehyde, formic acid can then be metabolized to carbon dioxide and water, although much more slowly than the FDH/ADH3-dependent metabolism of formaldehyde (55 minute [min]
|
From page 304... ...
Formaldehyde is not generally expected to be absorbed into the bloodstream and carried as an unmetabolized molecule to other organ systems. Thus, distribution and excretion are not thought to be significant considerations with formaldehyde exposure and toxicity.
|
From page 305... ...
These results should be viewed with some caution because gavage exposures may have a greater potential to overwhelm formaldehyde metabolic capabilities, resulting in greater distribution and toxicity of formaldehyde than might be experienced with episodic drinking water exposures. Acute Toxicity (1-5 d)
|
From page 306... ...
80 mg/kg/d (LOAEL) , 4 wk Wistar rats, male Reduced weight gain Vargova et gavage al.
|
From page 307... ...
in formaldehyde- 1979 test sensitized individuals at this concentration 300 mg/kg/d (LOAEL) , 24 mo, but effects Wistar rats, male Mortality as early as 9 d, reduced weight gain Tobe et al.
|
From page 308... ...
1986 82 mg/kg/d (LOAEL) , 15 24 mo Wistar rats, male Reduced body weight; thickened limiting Til et al.
|
From page 309... ...
0,4% (6) 4,0% Drinking water 0% (control)
|
From page 310... ...
(1) 188 mg/kg/d 104 wk Sprague-Dawley Glandular stomach: 12% adenomatous polyp Soffritti et (incidences primarily rats, male and (male only)
|
From page 311... ...
8% (6) 4% Drinking water 11% (control)
|
From page 312... ...
(1993) found significantly reduced mean body weights relative to controls for rats exposed to 80 mg/kg/d, but not for the 20 and 40 mg/kg/d exposure groups.
|
From page 313... ...
. Significant reductions in body weight gain were also observed for rats of both sexes at 150 mg/kg/d and in male rats at 100 mg/kg/d.
|
From page 314... ...
(1989) study was marked ulceration and tissue changes within the forestomach and glandular stomach of rats of either sex following chronic formaldehyde exposure at the 300 mg/kg/d and 50 mg/kg/d doses.
|
From page 315... ...
Necropsies performed at weeks 53, 79, and 105 noted pronounced inflammatory changes in the forestomach and glandular stomach of rats in the high-dose group. These effects were noted in both male and female rats.
|
From page 316... ...
The authors did not find an association between formaldehyde exposures and nasopharyngeal cancers and concluded that "overall, the epidemiologic evidence now available indicates that if formaldehyde does cause nasopharyngeal cancers, then the increased risk is small." However, the International Agency for Research on Cancer (IARC 2004) recently upgraded its classification of formaldehyde from Group 2A to Group 1 (sufficient evidence from experimental animals and humans to conclude it is carcinogenic to humans)
|
From page 317... ...
(1997) found no increased lung cancer incidences for industrial workers in the available cohorts or in the case-control studies and concluded that the available epidemiologic evidence did not support an association between formaldehyde exposure and lung cancers.
|
From page 318... ...
(1989) conducted 2-y exposure studies in which Wistar rats were administered formaldehyde through drinking water.
|
From page 319... ...
for male and female rats exposed from 6 wk of age and in both female breeders and offspring when dosed with 313 mg/kg/d. Although the observed incidences were low, the authors noted that no similar tumors were reported in the control groups and that these cancers are very rare for untreated rats in their breeding colony.
|
From page 320... ...
and adenocarcinomas (2/50 for female rats) in the glandular stomach in the 188 mg/kg/d group (not reported in the earlier study)
|
From page 321... ...
. In Vivo Observations Although no genotoxicity studies involving oral exposures to formaldehyde are available, there are a number of in vivo inhalation exposure studies (in both humans and rodents)
|
From page 322... ...
(2001) conducted a thorough review of these animal studies and concluded that they generally did not report positive reproductive or developmental effects in association with formaldehyde exposure.
|
From page 323... ...
(1970) observed no malformations in 124 pups from female rats exposed to formaldehyde through drinking water at 0 or 1% hexamethylenetetramine over 2 wk of exposure.
|
From page 324... ...
. There are a tremendous number of studies that have demonstrated that closed-patch testing can result in ACD following formaldehyde exposure (see ATSDR 1999)
|
From page 325... ...
) was available, standard drinking water risk assessment assumptions for the general population (70 kg body weight, 2 L/d ingestion)
|
From page 326... ...
Chronic duration 7 (0.2 mg/kg/d) State of Action EPA oral RfD 0.1 CDHS California level 2003 Florida Water -- 6 FSTRAC guideline 1999 Maine Water -- 0.03 FSTRAC guideline 1999 Minnesota Water -- 1 FSTRAC guideline 1999 New Jersey Water -- 0.1 FSTRAC guideline 1999 Texas Water EPA oral RfD 4.9 TCEQ 2003 guideline Wisconsin Water -- 1 FSTRAC guideline 1999 a EPA health advisories are provided for different exposure durations.
|
From page 327... ...
Administered formaldehyde doses were 0, 1.2, 15, and 82 mg/kg/d for males and 0, 1.8, 21, and 109 mg/kg/d for females. At the highest dose level in both sexes, significant changes in the histopathology of the forestomach and glandular stomach were noted.
|
From page 328... ...
, which lower the allowable concentration of formaldehyde in water to account for non-drinking water exposures. California, which has an action level of 0.1 mg/L for formaldehyde in drinking water, used
|
From page 329... ...
. Gavage exposures may increase TABLE 7-4 Spacecraft Water Exposure Guidelines for Formaldehyde Duration Concentration (mg/L)
|
From page 330... ...
1989) Allergic Contact Dermatitis 30 mg/L (LOAEL)
|
From page 331... ...
. Given that a range of irritant responses is likely with drinking water exposures to formaldehyde, and considering that this type of sensitivity is not evaluated in astronaut health screening, an additional UF of 3 was applied in calculating the AC to account for variability in individual response.
|
From page 332... ...
(1989) observed significantly reduced weight gain, water intake, and food intake throughout much of their study (especially with the male rats)
|
From page 333... ...
1995) that does not already have contact dermatitis from exposure.
|
From page 334... ...
, cancer risks associated with low levels of formaldehyde exposure would be much lower than those based on extrapolations from doses sufficient to evidence cytotoxicity and cell proliferation (Schlosser et al.
|
From page 335... ...
1991. Covalent binding of inhaled formaldehyde to DNA in the res piratory tract of Rhesus monkeys: Pharmacokinetics, rat-to-monkey inter species scaling and extrapolation to man.
|
From page 336... ...
2001. A review of adverse pregnancy outcomes and formaldehyde exposure in human and animal studies.
|
From page 337... ...
1999. Summary of State and Federal Drinking Water Standards and Guidelines 1998-1999.
|
From page 338... ...
1995. North American contact dermatitis group standard tray patch test results (1992-1994)
|
From page 339... ...
1993. Formaldehyde exposure and respiratory cancer- a meta analysis of the epidemiologic evidence.
|
From page 340... ...
1980. Induction of squamous cell carcinomas of the rat nasal cavity by inhala tion exposures to formaldehyde vapor.
|
From page 341... ...
Formaldehyde 341 WHO (World Health Organization)
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.