E X T O X N E T

Extension Toxicology Network A Pesticide Information Project of Cooperative Extension Offices of Cornell University, Michigan State University, Oregon State University, and University of California at Davis. Major support and funding was provided by the USDA/Extension Service/National Agricultural Pesticide Impact Assessment Program.

P esticide

I nformation

P rofile Naled



Publication Date: 9/93

TRADE OR OTHER NAMES

REGULATORY STATUS

INTRODUCTION

Naled is one of a class of insecticides referred to as organophosphates. These chemicals act by interfering with the activities of cholinesterase, an enzyme that is essential for the proper working of the nervous systems of both humans and insects. Please refer to the Toxicology Information Brief on cholinesterase-inhibition for a more detailed description of this topic.

TOXICOLOGICAL EFFECTS

ACUTE TOXICITY

The organophosphate insecticides are cholinesterase inhibitors. They are highly toxic by all routes of exposure. When inhaled, the first effects are usually respiratory and may include bloody or runny nose, coughing, chest discomfort, difficult or short breath, and wheezing due to constriction or excess fluid in the bronchial tubes. Skin contact with organophosphates may cause localized sweating and involuntary muscle contractions. Eye contact will cause pain, bleeding, tears, pupil constriction, and blurred vision. Following exposure by any route, other systemic effects may begin within a few minutes or be delayed for up to 12 hours. These may include pallor, nausea, vomiting, diarrhea, abdominal cramps, headache, dizziness, eye pain, blurred vision, constriction or dilation of the eye pupils, tears, salivation, sweating, and confusion. Severe poisoning will affect the central nervous system, producing incoordination, slurred speech, loss of reflexes, weakness, fatigue, involuntary muscle contractions, twitching, tremors of the tongue or eyelids, and eventually paralysis of the body extremities and the respiratory muscles. In severe cases there may also be involuntary defecation or urination, psychosis, irregular heart beats, unconsciousness, convulsions and coma. Death may be caused by respiratory failure or cardiac arrest (9).

Some organophosphates may cause delayed symptoms beginning 1 to 4 weeks after an acute exposure which may or may not have produced more immediate symptoms. In such cases, numbness, tingling, weakness and cramping may appear in the lower limbs and progress to incoordination and paralysis. Improvement may occur over months or years, but some residual impairment may remain in some cases (9).

Naled may cause dermatitis (skin rashes) and skin sensitization (allergies) (2, 6). It is corrosive to the skin and eyes and may cause permanent damage (3). An aerial applicator developed contact dermatitis after using Dibrom. The exposed area became red and felt burned. Later, water filled blisters formed. They became itchy and dry, then flaked off (ACGIH TLVS 4th Ed. & Supplement. 1980).

The amount of a chemical that is lethal to one-half (50%) of experimental animals fed the material is referred to as its acute oral lethal dose fifty, or LD50. The oral LD50 for naled in rats is 50 to 281 mg/kg, in mice is 330 to 375 mg/kg, and in chickens is 281 mg/kg (2, 3). Rats have tolerated a dosage of 28 mg/kg/day for 9 weeks with no visible signs of poisoning and with only moderate inhibition of cholinesterase (2). The dermal LD50 for naled in rabbits is 1,100 mg/kg, and in rats is 800 mg/kg (2, 3).

The lethal concentration fifty, or LC50, is that concentration of a chemical in air or water that kills half of the experimental animals exposed to it for a set time period. The inhalation LC50 for naled in rats is 7.7 mg/kg, and 156 mg/kg in mice (9).

CHRONIC TOXICITY

Reproductive Effects

Teratogenic Effects

Mutagenic Effects

Carcinogenic Effects

Organ Toxicity

Fate in Humans and Animals

ECOLOGICAL EFFECTS

Effects on Birds

Effects on Aquatic Organisms

Effects on Other Animals (Nontarget species)

Naled is highly toxic to bees (3). Mule deer are more resistant than most wildlife species. The LD50 for naled in mule deer is 200 mg/kg (4).

ENVIRONMENTAL FATE

Breakdown of Chemical in Soil and Groundwater

Naled is not persistent in soil. It is rapidly broken down if wet, and it is moderately volatile (Spencer. Guide to Chem. in Crop Prot. 1982). Soil microorganisms break down most of the naled in the soil.

Breakdown of Chemical in Water

Naled may produce a pollution hazard if dilution water is improperly disposed of, or if run-off from fire control is not properly contained (11).

Breakdown of Chemical in Vegetation

Plants breakdown naled and DDVP is created by the debromination of the naled molecule in a 1:1 relationship. These can be further metabolized or evaporated off (17).

PHYSICAL PROPERTIES AND GUIDELINES

Naled is stable in anhydrous conditions, but rapidly degrades in the presence of water and by alkali. In water, it can become hydrolyzed with a half-life of 2 days at room temperature (9). Naled should be stored away from moisture. It is corrosive to metals and may attack some forms of plastic, rubber and coatings (8, 9). If it comes in contact with metals, reducing agents, or sulfhydryls, naled may release bromide and revert to dichlorvos (5). It produces highly toxic chloride fumes if it comes in contact with acids or acidic fumes (13).

Persons who work with organo-phosphate materials for long periods of time should have frequent blood tests of their cholinesterase levels. If the cholinesterase level falls below a critical point, no further exposure should be allowed until it returns to normal (10).

Protective clothing must be worn when handling naled. Before removing gloves, wash them with soap and water. Always wash hands, face and arms with soap and water before smoking, eating or drinking.

After work, remove all work clothes and shoes. Shower with soap and water. Wear only clean clothes when leaving the job. Wash contaminated clothing and equipment with soap and water after each use. Keep contaminated work clothes separate from regular laundry.

Exposure Guidelines:

OSHA TWA: 3 mg/m3 (9) ACGIH TWA (skin): 3 mg/m3 (9) NIOSH Recommended TWA (skin): 3 mg/m3 (9)

Physical Properties:

CAS #: 300-76-5 Specific gravity: 1.96 (9) Solubility in water: practically insoluble or insoluble (3, 9) Solubility: Freely soluble in alcohols aromatic solvents.

Slightly soluble in aliphatic hydrocarbons, aromatic hydrocarbons, chlorinated hydro-carbons and ketones.

Sparingly soluble in mineral oils and petroleum solvents (3, 13, 15) Boiling point: 110 degrees C (252 degrees F) at 5 mm Hg (technical) (2, 9) Melting point: 81 degrees F (27 degrees C) (9) Vapor pressure: 2 x 10 to the minus 3 mm Hg at 20 degrees C (2) Oil: water partition coefficient Koc: 180 mg/l (7) Chemical class/use: organophosphate insecticide

BASIC MANUFACTURER

Review by Basic Manufacturer:

REFERENCES

Meister, R.T. (ed.) 1987. Farm Chemicals Handbook. Willoughby, OH: Meister Publishing Co. Hayes, W.J. and E.R. Laws (ed.). 1990. Handbook of Pesticide Toxicology, Vol. 3, Classes of Pesticides. Academic Press, Inc., NY. Meister, R.T. (ed.). 1992. Farm Chemicals Handbook '92. Meister Publishing Company, Willoughby, OH. Tucker, Richard. 1970. Handbook of toxicity of pesticides to wildlife. USDI Fish & Wildlife Service. Worthing, C.R. (ed.). 1987. The pesticide manual: A world compendium. 8th Ed. The British Crop Protection Council. Croydon, England. Hayes, Wayland, Jr. 1982. Pesticides studied in man. Baltimore, MD: Williams & Wilkins. U. S. Department of Agriculture, Soil Conservation Service. 1990 (Nov.). SCS/ARS/CES Pesticide Properties Database: Version 2.0 (Summary). USDA - Soil Conservation Service, Syracuse, NY. Hartley, D. and H. Kidd, (eds.) 1983. The agrochemicals handbook. Nottingham, England: Royal Society of Chemistry. Occupational Health Services, Inc. 1991 (June 9). MSDS for Naled. OHS Inc., Secaucus, NJ. Cheminova Agro A/S. 1991 (June 11). Material Safety Data Sheet. Cheminova, Lemvig, Denmark. Department of Transportation. 1984. Emergency Response Guidebook: Guidebook for hazardous materials incidents. Washington, DC: U.S. DOT. TOXNET. 1985. National library of medicine's toxicology data network. Hazardous Substances Databank. Public health Service. National Institute of Health. U.S. Department of Health and Human Services. Bethesda, MD: NLM. Sax, N.I. 1975. Dangerous properties of industrial materials. 4th Ed. New York: Van Nostrand Reinhold Co. Gosselin, R.E. 1984. Clinical toxicology of commercial products. 5th Ed. Baltimore, MD: Williams & Wilkins. Windholz, M. (ed.) 1976. The Merck Index: an encyclopedia of chemicals and drugs. 9th Ed. Rahway, NJ: Merck. Valent USA Corporation. March 1993. Dibrom concentrate - for use in mosquito control programs. Review by Valent Corporation. April, 1993.