40 CFR § 464.21 - Specialized definitions.

---
identifier: "/us/cfr/t40/s464.21"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 464.21 - Specialized definitions."
title_number: 40
title_name: "Protection of Environment"
section_number: "464.21"
section_name: "Specialized definitions."
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "N"
subchapter_name: "EFFLUENT GUIDELINES AND STANDARDS"
part_number: "464"
part_name: "METAL MOLDING AND CASTING POINT SOURCE CATEGORY"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "Secs. 301, 304 (b), (c), (e), and (g), 306 (b) and (c), 307, 308, and 501 of the Clean Water Act (Federal Water Pollution Control Act Amendments of 1972, as amended by the Clean Water Act of 1977) (the “Act”); 33 U.S.C. 1311, 1314 (b), (c), (e) and (g), 1316 (b) and (c), 1317 (b) and (c), 1318, and 1361; 86 Stat. 816, Pub. L. 92-500; 91 Stat. 1567, Pub. L. 95-217."
regulatory_source: "50 FR 45247, Oct. 30, 1985, unless otherwise noted."
cfr_part: "464"
---


# 464.21 Specialized definitions.

For the purpose of this subpart:

(a) *Total Toxic Organics* (*TTO*). TTO is a regulated parameter under PSES (§ 464.25) and PSNS (§ 464.26) for the copper subcategory and is comprised of a discrete list of toxic organic pollutants for each process segment where it is regulated, as follows:

(1) Casting Quench (§§ 464.25(a) and 464.26(a)):

23. chloroform (trichloromethane)

64. pentachlorophenol

66. bis(2-ethylhexyl)phthalate

71. dimethyl phthalate

(2) Dust Collection Scrubbers (§ 464.25(c) and 464.26(c)):

1. acenaphthene

22. para-chloro meta-cresol

23. chloroform (trichloromethane)

34. 2,4-dimethylphenol

55. naphthalene

58. 4-nitrophenol

64. pentachlorophenol

65. phenol

66. bis(2-ethylhexyl)phthalate

67. butyl benzyl phthalate

68. di-n-butyl phthalate

70. diethyl phthalate

71. dimethyl phthalate

72. benzo(a)anthracene (1,2-benzanthracene)

74. 3,4-benzofluoranthene

75. benzo(k) fluoranthene

76. chrysene

77. acenaphthylene

78. anthracene

81. phenanthrene

84. pyrene

(3) Investment Casting (§ 464.25(e) and § 464.26(e)):

1. acenaphthene

22. para-chloro meta-cresol

23. chloroform (trichloromethane)

34. 2,4-dimethylphenol

55. naphthalene

58. 4-nitrophenol

64. pentachlorophenol

65. phenol

66. bis (2-ethylhexyl)phthalate

67. butyl benzyl phthalate

68. di-n-butyl phthalate

70. diethyl phthalate

71. dimethyl phthalate

72. benzo(a)anthracene (1,2-benzanthracene)

74. 3,4-benzofluoranthene

75. benzo(k) fluoranthene

76. chrysene

77. acenaphthylene

78. anthracene

81. Phenanthrene

84. pyrene

(4) Melting Furnace Scrubber (§ 464.25(f) and § 464.26(f)):

1. acenaphthene

22. para-chloro meta-cresol

23. chloroform (trichloromethane)

34. 2,4-dimethylphenol

55. naphthalene

58. 4-nitrophenol

64. pentachlorophenol

65. phenol

66. bis (2-ethylhexyl) phthalate

67. butyl benzyl phthalate

68. di-n-butyl phthalate

70. diethyl phthalate

71. dimethyl phthalate

72. benzo(a)anthracene (1,2-benzanthracene)

74. 3,4-benzoflouranthene

75. benzo(k) flouranthene

76. chrysene

77. acenaphthylene

78. anthracene

81. phenanthrene

84. pyrene

(5) Mold Cooling (§ 464.25(g) and § 464.26(g)):

23. chloroform (trichloromethane)

64. pentachlorophenol

66. bis(2-ethylhexyl)phthalate

71. dimethyl phthalate