Historical Summary of 2-Naphthalene
Naphthalene is a white, crystalline powder with a characteristic odor. 2-Naphthylamine was commercially produced in the United States from at least the early 1920s to the early 1970s. It formerly was used commercially as an intermediate in the manufacture of dyes, as an antioxidant in the rubber industry, and to produce 2-chloronaphthylamine. Research into Naphthalene extends back to Ludwig Rehn’s study on the cuases of bladder tumors, and was continued by Wilhelm Hueper’s DuPont funded study of “Beta Naphthylamine”.
There is sufficient evidence for the carcinogenicity of 2-naphthylamine in experimental animals. When administered orally, 2-naphthylamine caused malignant bladder tumors in hamsters, dogs, and rhesus monkeys and liver tumors in mice; bladder tumors also were observed in rats at a low incidence Effects of naphthalene inhalation in humans include headache, confusion, eye irritation, nausea, profuse perspiration with vomiting, optic neuritis, hematuria, and edema. Naphthalene ingestion has resulted in abdominal pain, nausea, vomiting, diarrhea, darkening of the urine, irritation of the bladder, jaundice, anemia, and hyperthermia.
Naphthalene was nominated by NIOSH, OSHA, and EPA for carcinogenic evaluation because published evidence was inadequate for reaching a regulatory decision, and because of the potential for chronic exposure to humans through the use of mothballs in the home
Naphthalene has a boiling point of 217.9" C, a melting point of 80.2" C, a specific gravity of 1.14 at 4" C, a vapor pressure of 1 mm at 52.5" C, and vapor density of 4.4. It is insoluble in water. Chemical Formula: C10H8 Molecular Weight: 128.16
Specific Answers
Methodologies
Case studies were used for evidence of human carcinogens. Mouse and rat carcinogenicity bioassays were used. Both types of studies have been ongoing since the early 1900s.
Bias and Confounding
There is limited evidence of carcinogenicity from studies in humans, which indicates that causal interpretation is credible but that alternative explanations such as chance, bias or confounding factors could not adequately be excluded;
Sample Size
Varied according to test. The Sample size used in the below referenced mice study was
Detection Limits
The current Occupational Health and Safety Administration (OSHA) limit for naphthalene is 10 ppm in the air per 8-hour work shift. The American Conference of Governmental Hygienists reports that the odor threshold for naphthalene is at least as low as 0.3 ppm.
Dose-Response Relationships
Statistical analyses were conducted on the slopes of the dose-response curves and the individual dose points. An SCE frequency 20% above the concurrent solvent control value was chosen as a statistically conservative positive response. The probability of this level of difference occurring by chance at one dose point is less than 0.01; the probability for such a chance occurrence at two dose points is less than 0.001. An increase of 20% or greater at any single dose was considered weak evidence of activity; increases at two or more doses resulted in a determination that the trial was positive. A statistically significant trend (P<0.005)>
Naphthalene is a white, crystalline powder with a characteristic odor. 2-Naphthylamine was commercially produced in the United States from at least the early 1920s to the early 1970s. It formerly was used commercially as an intermediate in the manufacture of dyes, as an antioxidant in the rubber industry, and to produce 2-chloronaphthylamine. Research into Naphthalene extends back to Ludwig Rehn’s study on the cuases of bladder tumors, and was continued by Wilhelm Hueper’s DuPont funded study of “Beta Naphthylamine”.
There is sufficient evidence for the carcinogenicity of 2-naphthylamine in experimental animals. When administered orally, 2-naphthylamine caused malignant bladder tumors in hamsters, dogs, and rhesus monkeys and liver tumors in mice; bladder tumors also were observed in rats at a low incidence Effects of naphthalene inhalation in humans include headache, confusion, eye irritation, nausea, profuse perspiration with vomiting, optic neuritis, hematuria, and edema. Naphthalene ingestion has resulted in abdominal pain, nausea, vomiting, diarrhea, darkening of the urine, irritation of the bladder, jaundice, anemia, and hyperthermia.
Naphthalene was nominated by NIOSH, OSHA, and EPA for carcinogenic evaluation because published evidence was inadequate for reaching a regulatory decision, and because of the potential for chronic exposure to humans through the use of mothballs in the home
Naphthalene has a boiling point of 217.9" C, a melting point of 80.2" C, a specific gravity of 1.14 at 4" C, a vapor pressure of 1 mm at 52.5" C, and vapor density of 4.4. It is insoluble in water. Chemical Formula: C10H8 Molecular Weight: 128.16
Specific Answers
Methodologies
Case studies were used for evidence of human carcinogens. Mouse and rat carcinogenicity bioassays were used. Both types of studies have been ongoing since the early 1900s.
Bias and Confounding
There is limited evidence of carcinogenicity from studies in humans, which indicates that causal interpretation is credible but that alternative explanations such as chance, bias or confounding factors could not adequately be excluded;
Sample Size
Varied according to test. The Sample size used in the below referenced mice study was
Detection Limits
The current Occupational Health and Safety Administration (OSHA) limit for naphthalene is 10 ppm in the air per 8-hour work shift. The American Conference of Governmental Hygienists reports that the odor threshold for naphthalene is at least as low as 0.3 ppm.
Dose-Response Relationships
Statistical analyses were conducted on the slopes of the dose-response curves and the individual dose points. An SCE frequency 20% above the concurrent solvent control value was chosen as a statistically conservative positive response. The probability of this level of difference occurring by chance at one dose point is less than 0.01; the probability for such a chance occurrence at two dose points is less than 0.001. An increase of 20% or greater at any single dose was considered weak evidence of activity; increases at two or more doses resulted in a determination that the trial was positive. A statistically significant trend (P<0.005)>
References: http://ntp.niehs.nih.gov/?objectid=07081648-F15B-C689-A21D232EED7BB32F
http://www.inchem.org/documents/iarc/suppl7/naphthylamine2.html
http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=10007
http://ntp.niehs.nih.gov/ntp/newhomeroc/roc11/NaphthalenePub.pdf
http://ntp.niehs.nih.gov/?objectid=BCBBF9C2-123F-7908-7B9242421803DAA9
http://www.inchem.org/documents/iarc/suppl7/naphthylamine2.html
http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=10007
http://ntp.niehs.nih.gov/ntp/newhomeroc/roc11/NaphthalenePub.pdf
http://ntp.niehs.nih.gov/?objectid=BCBBF9C2-123F-7908-7B9242421803DAA9
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