DDT is a persistent organochlorine pesticide and is largely responsible for the great decrease in the reproductive capabilities and consequently in the populations of fish-eating birds, such as the bald eagle, brown pelican, and osprey. Because of DDT's effects on birds, the chemical has not been used in the United States since 1972, and can no longer be used except in cases of public health emergency. At the time Joni wrote this lyric (1967-68), the continued use of DDT was quite controversial. DDT is still used in several other areas of the world.
From the National Safety Council (USA):
Description:

DDT [1,1,1-trichloro-2, 2-bis-(p-chlorophenyl)ethane] was (C.A.S. 50-29-3) one of the most widely used chemicals for the control of insects on agricultural crops and insects which carry diseases such as malaria and typhus. Technical DDT is primarily composed of three forms (p,p'-DDT, o,p'-DDT, and o,o'-DDT) which are white, crystalline, tasteless, and almost odorless solids.

DDE [1,1-dichloro-2, 2-bis(p-chlorophenyl)ethylene] and DDD [1,1-dichloro-2, 2-bis(p-chlorophenyl)ethane] are found in small amounts as contaminants in technical DDT. DDD was also used as a pesticide; one form of DDD was used medically in the treatment of cancer of the adrenal gland.

DDT does not occur naturally in the environment. The presence of DDT in the environment is generally a result of contamination due to its past production and use, and its subsequent movement from sites of application to land, water, and air.

DDT, DDE, DDD, and other persistent organochlorine pesticides are responsible for the great decrease in the reproductive capabilities and consequently in the populations of fish-eating birds, such as the bald eagle, brown pelican, and osprey. They have also been shown to decrease the populations of numerous other species of water birds, raptors, and passerines, and are also highly toxic to aquatic organisms.

Because of DDT's effects on birds, the chemical has not been used in the United States since 1972, and can no longer be used except in cases of public health emergency. It is still used in several other areas of the world. Use of DDD as a pesticide is also banned.

Though DDT is no longer produced in this country, quantities ranging from small containers to stockpiles, produced more than 20 years ago, are occasionally still found because of its widespread use until the early 1970s.

Chemical properties:

Synonyms for DDT are 1,1'-(2,2,2-trichloroethylidene) Bis (4-chlorobenzene); 1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethane; 1,1,1-trichloro-2,2-di (4-chlorophenyl) ethane; 1,1,1-trichloro-2,2-di(p-chlorophenyl) ethane; 1,1-bis(4-chlorophenyl)-2,2,2-trichlorethane; 1,1-bis(p-chlorophenyl)-2,2,2-trichlorethane; 2,2,2-trichloro-1,1-bis (4-chlorophenyl) ehtane; 2,2-bix(p-chlorophenyl)-1,1,1-trichloroethane; 4,4'-DDT; 4,4'-dichlorodiphenyltrichloroethane; aavero-extra; agritan; alpha, alpha-bis (p-chlorophenyl)-beta,beta,beta-trichlorethan; anofex; arkotine; azotox; azotox m 33; benzochloryl; bosan supra; bovidermol; chlorophenothane; chlorophenotoxum; chlorphenothan; chlorphenotoxum; citox; clofenotan; clofenotane; DDT (DOT French); DDT (DOT Spanish); dedelo; deoval; detox; detoxan; dibovan; dichlorodiphenyltrichlorethane (DDT) (DOT French); dichlorodipheyltrichloroethane; dichlorodiphenyltrichloroethane (DDT)dichlorodifeniltrichloroethano (DDT) (DOT Spanish); dicophane; didigam; didimac; diphenyltrichloroethane; dodat; dykol; ent 1,506; ent-1506; estonate;ethane, 1,1,1-trichloro-2,2-bis(4-chlorophenyl)-; ethane, 1,1,1-trichloro-2,2-bis(p-chlorophenyl)-; genitox; gesafid; gesapon; gesarex; gesarol; guesapon; guesarol; gyron; havero-extra; hildit; ivoran; ixodex; kopsol; micro DDT 75; mutoxan; mutoxin; na 2761; nci-c00464; neocid; neocidol (solid); oms 16; p,p'- DDT; p,p'-dichlorodiphenyltrichloroethane; p,p'- Dichlorodiphenyltrichloromethylmethane; parachlorocidum; peb1; pentachlorin; pentech; penticidum; ppzeidan; r50; RCRA waste number U061; Rukseam; Santobane; Tafidex; Tech DDT; Trichlorobis (4'-chlorophenyl) ethane; Trichlorobis (4-chlorophenyl) ethane; Zeidane; and Zerdane.

Synonyms for DDE are DDT dihydrochloride; p,p'-DDE; dichlorodiphenyldichloroethylene; and 1,1-dichloro-2,2-bis(p- chlorophenyl)ethylene.

Synonyms for DDD are 1,1-bis(4-chlorophenyl)-2,2-dichloroethane; 4,4'-DDD; 1,1- dichloro-2,2-bis(p-chlorophenyl)ethane; and TDE.

DDT is insoluble in water, but very soluble in ethyl ether, acetone, benzene, and other organic solvents. DDE is slightly soluble in water, lipids, and most organic solvents. DDD is insoluble in water.

DDT can dehydrochlorinate at temperatures above its melting point, and in organic solvents in the presence of alkalies or organic bases. It is stable in strong acids and can withstand acid permanganate oxidation.

Identification:

Chemical Name: DDT
Regulatory Name: DDT
Formula: C14H9C15
DOT Label: Keep away from food
CAS: 50-29-3
CHRIS: DDT
UN Number: 2761
Health effects:

Although DDT has not been used in this country since 1972, under certain conditions, small amounts of DDT and DDE can remain in soil for a long time and may be transferred to crops grown on this soil. In addition, imported foods may have been directly exposed to DDT.

DDT is listed in the National Toxicology Program's Fifth Annual Report on Carcinogens as a "substance which may reasonably be anticipated to be carcinogen." The EPA categorizes DDT, DDE, and DDD as probable human carcinogens.

Individuals involved in the formulation of DDT have contracted rashes or irritation of the eyes, nose, and throat. Acute exposure at high doses primarily affects the nervous system. Longer term exposure to DDT may also affect the liver. In low doses, DDT may increase the ability of the liver to metabolize some compounds, while at higher doses, it may cause unusual growths or tumors or death of whole groups of cells (necrosis).

Children who are breast-fed are at special risk of exposure to DDT, because DDT is ubiquitous and is found in human milk in higher concentrations than those in cow's milk or other food. People more susceptible to the toxic effects of DDT are individuals with diseases of the nervous system, liver, or blood.

Exposure Values:

IDLH: 500 mg/m3; Not applicable for DDT, a potential human carcinogen. NIOSH)
TLV TWA: 1 mg/m3 (ACGIH, 1999)
NIOSH REL: Ca TWA 0.5 mg/m3
OSHA PEL: TWA 1 mg/m3 [skin]


Economics:

U.S. manufacturer of DDT is Lobel Chemical Corporation, New York, NY.

There has been no DDT imported into the United States since 1972.

Regulation:

EPA offices overseeing regulations and guidelines applicable to DDT, DDE, and DDD are Drinking Water, Emergency and Remedial Response, Solid Waste, and Toxic Substances. EPA cancelled most DDT use under the Federal Insecticide, Fungicide, and Rodenticide Act.

The Federal Drug Administration regulates the amount of DDT residues on tomatoes and dried tomato pumace for use in dog and cat food. The Occupational Safety and Health Administration has established permissible exposure limits for DDT.

Under Section 313 of the Emergency Planning and Community Right-to-Know Act of 1986, releases of more than one pound of DDT, DDE and DDD into the air, water, or land must be reported annually and entered into the National Toxic Release Inventory (TRI) data base.

Notations:

The NIOSH recommended exposure limits (RELs) are time-weighted average (TWA) concentrations for up to a 10-hour workday during a 40-hour workweek. A short-term exposure limit (STEL) is designated by "ST" preceding the value; unless noted otherwise, the STEL is a 15-minute TWA exposure that should not be exceeded at any time during a workday. A ceiling REL is designated by "C" preceding the value. Any substance that NIOSH considers to be a potential occupational carcinogen is designated by the notation "Ca."

The OSHA permissible exposure limits (PEL) are found in Tables Z-1, Z-2, and Z-3 of the OSHA General Industry Air Contaminants Standard (29 CFR 1910.1000). Unless noted otherwise, PEL are TWA concentrations that must not be exceeded during any 8-hour workshift of a 40-hour workweek. A STEL is designated by "ST" preceding the value and is measured over a 15-minute period unless noted otherwise. OSHA ceiling concentrations (designated by "C" preceding the value) must not be exceeded during any part of the workday; if instantaneous monitoring is not feasible, the ceiling must be assessed as a 15-minute TWA exposure. In addition, there are a number of substances from Table Z-2 (e.g., beryllium, ethylene dibromide, etc.) that have PEL ceiling values that must not be exceeded except for specified excursions. For example, a "5-minute maximum peak in any 2 hours" means that a 5-minute exposure above the ceiling value, but never above the maximum peak, is allowed in any 2 hours during an 8-hour workday.