Herbicides are used routinely to control noxious plants and have also been used in warfare and conflict. Most of these chemicals, particularly the more recently developed synthetic organic herbicides, are quite selective for specific plants and have low toxicity for mammals; other, less-selective compounds (eg, sodium arsenite, arsenic trioxide, sodium chlorate, ammonium sulfamate, borax, and many others) were formerly used on a large scale and are more toxic to animals.
Vegetation treated with herbicides at proper rates normally will not be hazardous to animals, including people. Particularly after the herbicides have dried on the vegetation, only small amounts can be dislodged. When herbicide applications have been excessive, damage to lawns, crops, or other foliage is often evident.
The residue potential for most of these agents is low. However, runoff from agricultural applications and entrance into drinking water cannot be excluded. The possibility of residues should be explored if significant exposure of food-producing animals occurs. The time recommended before treated vegetation is grazed or used as animal feed is available for a number of products.
Most health problems in animals result from exposure to excessive quantities of herbicides because of improper or careless use or disposal of containers. When herbicides are used properly, poisoning problems in veterinary practice are rare. With few exceptions, it is only when animals gain direct access to the product that acute poisoning occurs.
Acute signs usually will not lead to a diagnosis, although acute GI signs are frequent. All common differential diagnoses should be excluded in animals showing signs of a sudden onset of disease or sudden death. The case history is critical. Sickness after feeding, spraying of pastures or crops adjacent to pastures, a change in housing, or direct exposure may lead to a tentative diagnosis of herbicide poisoning. Generally, the nature of exposure is hard to identify because of storage of herbicides in mis- or unlabeled containers. Unidentified spillage of liquid from containers or powder from torn or damaged bags near a feed source, or visual confusion with a dietary ingredient or supplement, may cause the exposure. Once a putative chemical source has been identified, an animal poison control center should be contacted for information on treatments, laboratory tests, and likely outcome.
Chronic disease caused by herbicides is even more difficult to diagnose. It may include a history of herbicide use in proximity to the animals or animal feed or water source, or a gradual change in the animals’ performance or behavior over a period of weeks, months, or even years. Occasionally, it involves manufacture or storage of herbicides nearby. Samples of possible sources (ie, contaminated feed and water) for residue analysis, as well as tissues from exposed animals taken at necropsy, are essential. Months or even years may be required to successfully identify a problem of chronic exposure.
To recognize whether an animal has been exposed to herbicides or accidental poisoning, standardized analytical procedures for diagnostic investigation of biologic materials have become established and are subsumed under the term biomonitoring. Accurate biomonitoring is an important tool to evaluate human or animal exposure to such herbicides by measuring the levels of these chemicals, their metabolites, or altered biologic structures or functions in biologic materials such as urine, blood or blood components, exhaled air, hair or nails, and tissues. The use of urine is advantageous because of ready availability. As such, urine has been used for biomonitoring of several herbicides, including 2,4-D, 2,4,5-T, MCPA (2-methyl-4-chlorophenoxyacetic acid), atrazine, diuron, alachlor, metolachlor, paraquat, diquat, imazapyr, imazapic, imazethapyr, imazamox, imazaquin, and imazamethabenz-methyl herbicides, with the objective to assess exposure and health risk to exposed animals.
If poisoning is suspected, the first step in management is to halt further exposure. Animals should be separated from any possible source before attempting to stabilize and support them. If there are life-threatening signs, efforts to stabilize animals by general mitigation methods should be started. Specific antidotal treatments, when available, may help to confirm the diagnosis. As time permits, a more detailed history and investigation should be completed. The owner should be made aware of the need for full disclosure of facts to successfully determine the source of poisoning, eg, unapproved use or failure to properly store a chemical.
Toxicity and Management of Poisoning
Herbicide Poisoning
Compound | Acute Oral LD50—Rat | NOAELa (oral) | Acute Dermal LD50 | Avian Toxicity/NOAECb | Toxicity to Fish in Water | Skin and Eye Irritation |
|---|---|---|---|---|---|---|
Acetochlor | 2,148–2,950 mg/kg | Dog, 1 year 12 mg/kg/day | Rabbit 4,166 mg/kg | LC50 5 day Bobwhite quail and Mallard duck 5,620 mg/kg | LC50 96 hours Rainbow trout 0.45 mg/L | Skin–mild Eye–mild |
Acifluorfen | 1,300 mg/kg (F) | Rat, 2 years 180 ppm | Rabbit >2,000 mg/kg | LC50 8 day Mallard duck >10,000 mg/kg | LC50 96 hours Rainbow trout 31 mg/L | Skin–moderate Eye–severe |
Acrolein | 29 mg/kg | Rat, 13 weeks 150 mg/L in drinking water | Rabbit 231 mg/kg | LD50 (oral) Bobwhite quail 19 mg/kg Mallard duck 9.1 mg/kg | LC50 24 hours Bluegill and Rainbow trout 0.024 mg/L | Skin–severe Eye–severe |
Alachlor | 930–1,200 mg/kg | Dog, 90 days < 200 mg/kg/day | Rabbit 13,300 mg/kg | Skin–mild | ||
Ametryn | 1,009–1,405 mg/kg | Rat reproduction, 50 ppm | Rabbit 2,020 mg/kg | LD50 (oral) Birds >2,250 mg/kg LC50 5 day Birds >5,620 ppm | Skin–irritation Guinea pig–dermal sensitization Eye–mild | |
alpha-Metolachlor | 2,675–2,952 mg/kg | Dog, 90 days 0.0125 mg/kg/day | Rat 2,020 mg/kg | LC50 8 day Bobwhite quail and Mallard duck >10,000 ppm | LC50 96 hours Bluegill and Rainbow trout 3.9–10 ppm | Skin–slight Eye–mild |
Atrazine | 2,000–3,080 mg/kg | Dog, 1 year 150 ppm Rat, 2 years 10 ppm | Rabbit 7,500 mg/kg | LC50 8 day Mallard duck >10,000 ppm in diet | LC50 96 hours Rainbow trout 8.8 mg/L | Skin–slight |
Amitrole | 4,080 mg/kg (M) | Rat, 13 weeks 2 mg/kg/day | Rat >5,000 mg/kg | LD50 Mallard duck 2,000 mg/kg | Skin–mild Eye–mild | |
Ammonium sulfamate | 3,900 mg/kg | Rat, 105 days 10,000 mg/kg/day | LD50 Bobwhite quail 3,000 mg/kg | LC50 48 hours Crucian carp 1,000–2,000 mg/L | Skin–none | |
Bensulfron methyl | >5,000 mg/kg | Rat, dog, 2 years 750 ppm in diet | Rat >2,000 mg/kg | LC50 96 hours Bluegill and Rainbow trout >150 ppm | Skin–none Eye–serious | |
Bensulidec | 271–770 mg/kg | Dog, 90 days 12.5 mg/kg/day | Rabbit 3,950 mg/kg | LD50 Bobwhite quail 3 weeks 50 mg/kg, poor hatchability | LC50 96 hours Bluegill 1.4 mg/L Rainbow trout 0.7 mg/L | Eye–none |
Bentazon | 1,100 mg/kg (cat 500 mg/kg) | Rat, 90 days 3.5 mg/kg/day Dog, 90 days 7.5 mg/kg/day | Rat >2,500 mg/kg | LD50 Japanese quail 720 mg/kg Mallard duck 2,000 mg/kg | LC50 96 hours Bluegill 616 mg/L Rainbow trout 1,060 mg/L | Slight irritant |
Bispyribac sodium | Rat, 2 years 1.1 mg/kg/day (M) 1.4 mg/kg/day (F) | LC50 Bobwhite quail and Mallard duck >5,620 ppm | LC50 96 hours Bluegill and Rainbow trout >100 ppm | Skin–minor Eye–minor | ||
Borax | 2,000–6,000 mg/kg | |||||
Bromacil | 5,200 mg/kg | Rat, dog, 2 years 250 mg/kg/day | Rabbit >5,000 mg/kg | LC50 8 day Bobwhite quail and Mallard duck >10,000 mg/kg | LC50 48 hours Bluegill 71 mg/L Rainbow trout 56 mg/L | Skin–irritating Eye–irritating |
Bromoxynil | 190–779 mg/kg | Rat, 90 days 50 mg/kg/day | Rabbit >2,000 mg/kg | Acute LD50 Bobwhite quail 100 mg/kg Mallard duck 200 mg/kg | LC50 96 hours Rainbow trout 0.05 mg/L | Skin–none Eye–none |
Butachlorc | 2,000–3,300 mg/kg | Rabbits maternal and fetal effects, 50 mg/kg/day | Rat >13.3 g/kg | Skin–none Eye–moderate Guinea pig–dermal sensitization | ||
Butylatec | >5,431 mg/kg (M) 4,659 mg/kg (F) | Rat, 2 years 20 mg/kg/day Dog, 1 year 25 mg/kg/day | Rabbit >4,640 mg/kg | LC50 8 day Bobwhite quail 40,000 mg/kg Mallard duck 46,400 ppm in diet | LC50 96 hours Bluegill 6.9 mg/L Rainbow trout 4.2 mg/L | Skin–moderate Eye–mild |
Carfentrazone ethyl | >5,000 mg/kg | Rat, 2 years 9 mg/kg/day (M) 3 mg/kg/day (F) | Rat >5,000 mg/kg | LC50 Bobwhite quail and Mallard duck >5,620 ppm | LC50 96 hours Bluegill 2 ppm Rainbow trout 16 ppm | Skin–none to slight Eye–minimum |
Chloramben | 5,620 mg/kg | Rabbit >3,160 mg/kg | LC50 8 day Mallard duck >4,640 mg/kg | Not toxic to fish | Skin–mild Eye–mild | |
Chlorotoluron | >10,000 mg/kg | LC50 96 hours Rainbow trout >100 mg/L | ||||
Chlorpropham | 4,100–7,000 mg/kg | Rat, dog, 2 years 100–350 mg/kg/day | LD50 8 day Mallard duck >2,000 mg/kg | LC50 48 hours Bluegill 6.3–6.8 mg/L Rainbow trout 3–6 mg/L | Skin–moderate Eye–moderate | |
Chlorsulfuron | 5,545 mg/kg (M) 6,293 mg/kg (F) | Rat, 2 years 100 ppm in diet | Rabbit >3,400 mg/kg | LC50 8 day Mallard duck >5,000 mg/kg | LC50 96 hours Rainbow trout >250 mg/L | Skin–none Eye–mild |
Chlorthal dimethyl | 3,000–12,000 mg/kg | Rat, 2 years < 50 mg/kg/day | Rabbit >2,000 mg/kg | LD50 young Bobwhite quail 5,500 mg/kg | Not toxic to fish | Skin–none Eye–mild |
Clethodim | 1,630 mg/kg (M) 1,360 mg/kg (F) | Dog, 1 year >1 mg/kg/day | Rabbit >5,000 mg/kg | LC50 8 day Bobwhite quail 4,270 ppm Mallard duck 3,978 ppm in diet | LC50 Bluegill 13 ppm Rainbow trout 18 ppm | Skin–none Eye–moderate |
Clodinafop propargyl | 1,392 mg/kg (M) 2,271 mg/kg (F) | Dog, 90 days 0.346 mg/kg/day (M) 1.89 mg/kg/day (F) | Rabbit >2,000 mg/kg | LC50 Birds >5,000 ppm | LC50 Freshwater fish 0.3 ppm | Skin–none Eye–slight to severe |
Clomazone | 2,077 mg/kg (M) 1,369 mg/kg (F) | Dog, 1 year < 2.5 mg/kg/day | Rabbit >2,000 mg/kg | LD50 8 day Bobwhite quail and Mallard duck 5,620 ppm in diet | LC50 96 hours Bluegill 34 mg/L Rainbow trout 19 mg/L | Skin–mild Eye–moderate |
Clopyralid | >4,300 mg/kg | Rat, 2 years 50 mg/kg/day | Rabbit >2,000 mg/kg | LC50 Bobwhite quail and Mallard duck >4,640 ppm in diet | LC50 96 hours Bluegill 125 mg/L Rainbow trout 103.5 mg/L | Skin–mild Eye–severe |
Cloransulam-methyl | >5,000 mg/kg | Dog, 1 year 10 mg/kg/day | Rabbit >2,000 mg/kg | LC50 5 day Bobwhite quail and Mallard duck >5,620 ppm | LC50 96 hours Bluegill >154 ppm Rainbow trout >86 ppm | Skin–none Eye–slight |
Copper chelate | 498 mg/kg | Rabbit >2,000 mg/kg | LC50 8 day Mallard duck >1,000 ppm in diet | LC50 96 hours Bluegill 1.2–7.5 mg/L Rainbow trout < 0.2–4 mg/L | Skin–slight Eye–moderate | |
Copper sulfate | 470 mg/kg | Rabbit >8,000 mg/kg | LD50 (oral) Pheasant 1,000 ppm in diet (estimated) | LC50 96 hours Bluegill 4.4–7.3 mg/L Rainbow trout 0.135 mg/L | Skin–moderate Eye–severe | |
Cyanazined | 182–334 mg/kg | Dog, 2 years < 225 mg/kg/day | Rabbit >2,000 mg/kg | LD50 Bobwhite quail 400 mg/kg Mallard duck >2,000 mg/kg | LC50 96 hours Bluegill 23 mg/L Rainbow trout 9 mg/L | Skin–none Eye–mild |
Cycloate | 2,000–3,190 mg/kg | Dog, 240 mg/kg/day | Rabbit >4,640 mg/kg | LC50 7 day Bobwhite quail >56,000 mg/kg | LC50 96 hours Rainbow trout 5.6 mg/L | Skin–none Eye–none |
Cyhalofopbutyl | >5,000 mg/kg | Dog, 46.7 mg/kg/day (M) 45.9 mg/kg/day (F) | Rat >5,000 mg/kg | LC50 96 hours Bluegill >99.2 mg/L Rainbow trout >1.65 mg/L | Skin–none Eye–minimal | |
Dalapon | 6,600–9,330 mg/kg | LC50 96 hours Fish 210–340 mg/L | ||||
Di-allated | 340–460 mg/kg | LC50 96 hours Fish 8.2 mg/L | ||||
2,4-D | 370–700 mg/kg | Rat, 2 years 50 mg/kg/day | Rabbit >2,000 mg/kg | LC50 8 day Mallard duck >4,640 mg/kg | LC50 96 hours Bluegill >300 mg/L Rainbow trout 800 mg/L | Skin–none Eye–moderate |
2,4-D dimethyl-amine | 949–4,650 mg/kg | Dog, 1 year 1 mg/kg/day | Rabbit >2,000 mg/kg | LC50 8 day Mallard duck >5,600 ppm | LC50 96 hours Bluegill 524 mg/L Rainbow trout 250 mg/L | Skin–minimal Eye–severe |
2,4-D isooctyl ester | 500–700 mg/kg | Dog, 1 year 1 mg/kg/day | Rabbit >2,000 mg/kg | As for 2,4-D (above) ––– | Skin–none Eye–severe | |
Dazomet | 551–646 mg/kg (M) 335–562 mg/kg (F) | Rat, 2 years 1.6 mg/kg/day | Rabbit >2,000 mg/kg | LD50 Bobwhite quail 415 ppm in diet | LC50 Rainbow trout 2.4–16.2 mg/L | Skin–mild Eye–severe |
Dicamba | 1,707 mg/kg | Rat, 2 years 125 mg/kg/day Dog, 2 years 50 mg/kg day | Rabbit >2,000 mg/kg | LC50 8 day Bobwhite quail and Mallard duck >4,600 mg/kg | LC50 96 hours Bluegill and Rainbow trout >1,000 mg/L | Skin–moderate Eye–extreme |
Dichlobenil | >3,160 mg/kg | Rat, 2 years >20 ppm in diet Pig, 6 months >50 ppm in diet | Rabbit >1,350 mg/kg | LC50 8 day Mallard duck >5,200 ppm in diet | LC50 96 hours Bluegill and Rainbow trout 7 mg/L | Skin–none Eye–mild to moderate |
Dichlorprop or 2,4-DP | 700 mg/kg (M) 500 mg/kg (F) | Rat, 4 mg/kg | Mouse 1,400 mg/kg | LC50 Upland birds, waterfowl >10,000 ppm in diet | LC50 Bluegill 1.1 mg/L Rainbow trout 100–200 mg/L | Skin–none Eye–none |
Diclosulam | >5,000 mg/kg | Rat, 0.05 mg/kg | Rabbit >2,000 mg/kg | LC50 Most sensitive aquatic species 10–100 mg/L | Skin–moderate Eye–moderate | |
Difenzoquat (methylsulfate) | 617 mg/kg (M) 373 mg/kg (F) | Dog, 1 year 20 mg/kg/day | Rabbit >2,000 mg/kg | LC50 8 day Bobwhite quail and Mallard duck 4,640 ppm in diet | LC50 96 hours Bluegill 696 mg/L Rainbow trout 711 mg/L | Skin–mild Eye–mild |
Diflufenzopyr | 1,600 to >5,000 mg/kg | Dog, 1 year 28 mg/kg/day (M) 26 mg/kg/day (F) | Rabbit >5,000 mg/kg | LC50 Mallard duck >5,620 ppm | LC50 Bluegill 135 ppm Rainbow trout 106 ppm | Skin–very slight Eye–mild to slight |
Dimethenamid | 429–1,293 mg/kg | Dog, 1 year 50–250 ppm in diet | Rabbit >2,000 mg/kg | LC50 Bobwhite quail and Mallard duck >5,620 ppm in diet | LC50 Bluegill 6.4 mg/L Rainbow trout 2.6 mg/L | Skin–mild Eye–moderate |
Dinoterb | 25 mg/kg | LC50 Partridges 3–5 ppm in diet | Toxic to fish | |||
Diquat | 231–440 mg/kg | Rat reproduction, 1 mg/kg/day | Rabbit >400 mg/kg | LC50 Partridges 270–300 ppm in diet | LC50 Fish 80–210 mg/L | Skin–none Eye–mild |
Dithiopyr | >5,000 mg/kg | Dog, 1 year < 0.5 mg/kg/day | Rabbit >5,000 mg/kg | LC50 Bobwhite quail and Mallard duck >5,260 ppm in diet | LC50 Bluegill 0.7 mg/L Rainbow trout 0.5 mg/L | Skin–slight Eye–moderate |
Diuron | 3,400 mg/kg | Dog, 2 years 25 mg/kg | Rat >2,000 mg/kg | LC50 Bobwhite quail 1,730 ppm Mallard duck >5,000 ppm in diet | LC50 Bluegill 7.4 mg/L Rainbow trout 4.3 mg/L | Skin–none Eye–mild |
DNOC | 25–85 mg/kg | Rat, 2 years 0.59 mg/kg/day | Rat 600–2,000 mg/kg Rabbit 1,000 mg/kg | LD50 Japanese quail 10–25 mg/kg | LC50 Fish 0.2–13 mg/L | Skin–erythema and edema Eyes–corrosive Guinea pig–dermal sensitization |
EPTC (s-ethyldipropylthiocarbamate) | 1,630 mg/kg | Dog, 90 days 20 mg/kg | Rabbit 2,750–5,000 mg/kg | LC50 7 day Bobwhite quail 20,000 ppm in diet | LC50 Bluegill 27 mg/L Rainbow trout 19 mg/L | Skin–mild Eye–severe |
Ethalfluralin | Rat >5,000 mg/kg (dog, cat >200 mg/kg) | Rat, mouse, 90 days 68 mg/kg | Rabbit >2,000 mg/kg | LC50 8 day Bobwhite quail and Mallard duck >5,000 ppm | LC50 Bluegill 0.03–0.1 mg/L Rainbow trout 0.037–0.136 mg/L | Skin–slight to moderate Eye–slight |
Ethephon | 1,600–4,229 mg/kg | Rat, 2 years 375 mg/kg/day Mouse, 78 weeks 4.5 mg/kg/day | Rabbit >5,000 mg/kg | LC50 8 day Mallard duck >10,000 ppm | LC50 96 hours Bluegill 222–300 mg/L Rainbow trout 254–350 mg/L | Skin–corrosive Eye–corrosive |
Fenoxapropd | 2,357 mg/kg (M) 2,500 mg/kg (F) | Dog, 2 years 0.375 mg/kg/day | Rabbit >1,000 mg/kg | LD50 Japanese quail >5,000 mg/kg | LC50 Bluegill 3.3 mg/L Rainbow trout 3.4 mg/L | Skin–slight Eye–serious nonreversible corneal opacity |
Fenoxaprop-ethyld | 4,430 mg/kg | Dog, 2 years 0.9 mg/kg/day | Rat >5,000 mg/kg | LC50 8 day Bobwhite quail and Mallard duck 5,620 ppm | LC50 Bluegill 0.31 mg/L Rainbow trout 0.46 mg/L | Skin–slight Eye–moderate |
Flamprop-methyl | 1,210 mg/kg | Dog, 2 years 10 mg/kg/day | Rat >294 mg/kg | LD50 Bobwhite quail 4,640 mg/kg Mallard duck >1,000 mg/kg | LC50 96 hours Rainbow trout 4.7 mg/L | Skin–none Eye–none |
Florasulam | >6,000 mg/kg | Dog, 1 year 5 mg/kg/day | Rabbit >2,000 mg/kg | LD50 14 day Japanese quail 175 mg/kg | LC50 96 hours Rainbow trout >100 mg/L | Skin–none Eye–none |
Fluazifop-p-butyl | 3,680–4,096 mg/kg (M) 2,451–2,721 mg/kg (F)e | Rat, 90 days >10 mg/kg/day | Rabbit >2,400 mg/kg | LD50 5 day Bobwhite quail >4,659 ppm Mallard duck >4,321 ppm | LC50 96 hours Bluegill 0.5 mg/L Rainbow trout 1.4 mg/L | Skin–slight Eye–mild |
Flucarbazone-sodium | >5,000 mg/kg | Dog, 1 year 35.9 mg/kg/day | Rat >5,000 mg/kg | NOAEC (reproduction) Mallard duck 233 mg/kg/day | NOAEL (chronic) Rainbow trout 2.75 mg/L | Skin–none Eye–minimal |
Flufenacet | 1,617 mg/kg (M) 589 mg/kg (F) | Dog, 1 year 1.29 mg/kg/day | Rat >2,000 mg/kg | LC50 5 day Bobwhite quail >5,317 ppm Mallard duck >4,970 ppm | LC50 Bluegill 2.26–2.4 ppm Rainbow trout 3.49–5.84 ppm | Skin–none Eye–minimal |
Flumetsulam | >5,000 mg/kg | Rat >2,000 mg/kg | LC50 Mallard duck >5,620 ppm | LC50 Bluegill >300 ppm Rainbow trout >293 ppm | Skin–none Eye–slight | |
Flumiclorac | 3,200 to >5,000 mg/kg | Dog, 1 year 100 mg/kg/day | Rat >2,000 mg/kg | LC50 Mallard duck >5,620 ppm | LC50 96 hours Bluegill 17.4 mg/L Rainbow trout 1.1 mg/L | Skin–severe Eye–moderate |
Fluometuron | >8,000 mg/kg | Rat, 103 weeks 125 mg/kg/day | Rat >2 g/kg Rabbit 10 g/kg | LC50 96 hours Bluegill 96 mg/L Rainbow trout 47 mg/L Crucian carp 17 mg/L | ||
Fluroxypyr | >5,000 mg/kg | Dog, 1 year 150 mg/kg/day | Rat >2,000 mg/kg | LC50 5 day Mallard duck >5,000 ppm | LC50 96 hours Bluegill 14.3 mg/L Rainbow trout 13.4–100 mg/L | Skin–none Eye–slight |
Fluthiacet | >5,000 mg/kg | Dog, 1 year 57.6 mg/kg/day (M) 30.3 mg/kg/day (F) | Rat >2,000 mg/kg | LC50 5 day Bobwhite quail and Mallard duck >5,620 ppm | LC5096 hours Bluegill 140 mcg/L Rainbow trout 43 mcg/L | Skin–none Eye–minimal |
Foramsulfuron | >3,881 mg/kg | Rat, 2 years 849 mg/kg/day (M) 1,135 mg/kg/day (F) | Rat >5,000 mg/kg | LC50 Bobwhite quail and Mallard duck >5,000 ppm | Skin–moderate Eye–mild | |
Fosamine ammonium | 24,000 mg/kg | Rat, 90 days 1,000 mg/kg | Rabbit >1,683 mg/kg | LD50 Mallard duck >10,000 ppm in diet | LC50 Bluegill 670 mg/L Rainbow trout 1,000 mg/L | Skin–none Eye–moderate to severe |
Glufosinate (ammonium salt) | 1,510–2,030 mg/kg | Dog, 1 year 5 mg/kg/day | Rat >1,390 mg/kg | LC50 5 day Japanese quail >5,000 mg/kg | LC50 96 hours Bluegill 56–75 mg/L Rainbow trout >26.7 mg/L | Skin–slight Eye–moderate to severe |
Glyphosate | 4,230–5,600 mg/kg | Dog, 2 years >500 mg/kg/day | Rabbit >5,000 mg/kg | LC50 8 day Bobwhite quail and Mallard duck 4,500 ppm in diet | LC50 96 hours Bluegill 120 mg/L Rainbow trout 86 mg/L | Skin–none Eye–slight to moderate |
Halosulfuron | 1,287 mg/kg | Dog, 13 weeks 10 mg/kg/day | Rat >5,000 mg/kg | LC50 5 day Bobwhite quail and Mallard duck >5,620 ppm | LC50 96 hours Bluegill >118 mg/L Rainbow trout >131 mg/L | Skin–slight Eye–slight |
Hexazinone | 1,690 mg/kg | Rat, 2 years 250 mg/kg in diet | Rabbit >5,278 mg/kg | LC50 5–8 day Bobwhite quail and Mallard duck >10,000 ppm in diet | LC50 96 hours Bluegill 370–420 mg/L Rainbow trout 320–420 mg/L | Skin–none Eye–severe but reversible |
Imazamethabenzmethyl | >5,000 mg/kg | Dog, 1 year 1,000 ppm | Rabbit >2,000 mg/kg | Skin–none Eye–slight | ||
Imazaquin | >5,000 mg/kg | Dog, 1 year 1,000 ppm | Rabbit >2,000 mg/kg | Skin–slight | ||
Imazamox | >5,000 mg/kg | Dog, 1 year 40,000 ppm | Rat >4,000 mg/kg | LC50 Mallard duck >5,672 ppm | LC50 96 hours Bluegill >119 ppm Rainbow trout >122 ppm | Skin–none Eye–none |
Imazapic | >5,000 mg/kg | Dog, 1 year 5,000 ppm | Rabbit >2,000 mg/kg | Skin–slight Eye–moderate | ||
Imazapyr | >5,000 mg/kg | Dog, 1 year feeding 1,000 ppm Rat 300 mg/kg/day (teratology) | Rabbit >2,000 mg/kg | LC50 8 day Bobwhite quail and Mallard duck >5,000 ppm in diet | LC50 96 hours Bluegill and Rainbow trout >100 mg/L | Skin–mild Eye–more severe |
Imazethapyr | >5,000 mg/kg | Dog, 1 year 25 mg/kg/day | Rabbit >2,000 mg/kg | LD50 Bobwhite quail and Mallard duck >2,150 ppm in diet | LC50 96 hours Bluegill 420 mg/L Rainbow trout 340 mg/L | Skin–mild Eye–irritation reversible |
Isoproturon | 1,800–2,400 mg/kg | Dog, 90 days Rat, 2 years 3 mg/kg/day | Rat >3.2 g/kg | LC50 96 hours Crucian carp 193 mg/L Rainbow trout 240 mg/L | Skin–none Eye–none | |
Isoxaflutole | >5,000 mg/kg | Dog, 1 year 1,200 ppm | Rat >2,000 mg/kg | LC50 5 day Bobwhite quail and Mallard duck >4,255 ppm | LC50 96 hours Bluegill >4.5 mg/L Rainbow trout >1.7 mg/L | Skin–minimal Eye–minimal |
Linuron | 1,200–4,000 mg/kg | Dog, 2 years 6.25 mg/kg/day (observed anemia) | Rabbit >5,000 mg/kg | LC50 5–8 day Japanese quail >5,000 ppm Mallard duck 3,083 ppm in diet | LC50 96 hours Bluegill and Rainbow trout 16 mg/L | Skin–mild Eye–moderate |
Maleic hydrazide | >5,000 mg/kg (acid) >6,950 mg/kg (Na+ salt) >3,900 mg/kg (K+ salt) | Dog, 1 year 25 mg/kg | Rabbit >20,000 mg/kg | LD50 Bobwhite quail and Mallard duck >10,000 mg/kg | LC50 96 hours Bluegill 1,608 mg/L Rainbow trout 1,435 mg/L | Skin–slight Eye–severe |
MCPA | 700–1,160 mg/kg | Rat, 7 months 100 mg/kg/day (lowers wt gain) | Rabbit 3,400–4,800 mg/kg | LD50 Bobwhite quail 377 mg/kg | LC50 96 hours Bluegill and Rainbow trout 90 mg/L | Skin–slight Eye–moderate |
MCPB | 4,700 mg/kg | Rat, 6 months 1.6 mg/kg/day | Rat >2,000 mg/kg | LC50 8 day Bobwhite quail and Mallard duck >5,000 ppm in diet | LC50 96 hours Bluegill 14 mg/L Rainbow trout 4.3 mg/L | Skin–moderate Eye–moderate |
Mecoprop | 930–1,210 mg/kg | Rat, 90 days 3.8 mg/kg/day Dog, 90 days 15 mg/kg/day | Rabbit 900 mg/kg | LC50 Bobwhite quail and Mallard duck 5,000–5,500 ppm in diet | LC50 96 hours Bluegill >100 mg/L Rainbow trout 124 mg/L | Skin–slight Eye–intense |
Mesotrione | >5,050 mg/kg | Rat >5,050 mg/kg | LD50 Bobwhite quail >2,000 mg/kg Mallard duck >5,200 mg/kg | LC50 96 hours Bluegill and Rainbow trout >120 mg/L | Skin–slight Eye–moderate | |
Metam (sodium and isothiocyanate) | 1,800 mg/kg (M) 1,700 mg/kg (F) 97 mg/kg (isothiocyanate) | Rat, 65 days (inhalation, in inspired air) 6 hours/day for 5 days/week at 0.045 mg/L | Rabbit 10,000 mg/kg | LC50 Bobwhite quail >10,000 Mallard duck >5,000 ppm in diet | LC50 96 hours Bluegill 0.047 mg/L Rainbow trout 0.029 mg/L | Skin–corrosive Eye–corrosive |
Methyl bromide | Acute LC50 (inhalation) 4.5 mg/L air | Safe threshold for people 0.065 mg/L air | Acute toxicity Bluegill 11 mg/L | Skin–severe Eye–severe | ||
Methyl isothiocyanate | 82 mg/kg (M) | Dog, 2 years 10 mg/L in drinking water | Rabbit 202 mg/kg (F) 145 mg/kg (M) | LC50 5 day Mallard duck 10,936 mg/kg | LC50 96 hours Bluegill 0.13 mg/L Rainbow trout 0.37 mg/L | Skin–corrosive Eye–severe |
Metobromuron | 2,450–2,500 mg/kg | Rat, 2 years 250 mg/kg/day Dog, 100 mg/kg/day | Rabbit >2,000 mg/kg | LC50 8 day Bobwhite quail >20,000 ppm Mallard duck >4,640 ppm in diet | LC50 96 hours Bluegill 4 mg/L Rainbow trout 3 mg/L | Skin–moderate Eye–moderate |
Metolachlorc | 800–2,780 mg/kg | Rat, 90 days 1,000 mg/kg Dog, 90 days 500 mg/kg | Rabbit >5,000 mg/kg Rat >10 g/kg | LC50 5 day Bobwhite quail and Mallard duck >10,000 ppm in diet | LC50 96 hours Bluegill 15 mg/L Rainbow trout 3 mg/L | Skin–none Eye–none |
Metosulam | >5,000 mg/kg | Dog, 1 year 10 mg/kg/day | Rabbit >2,000 mg/kg | Skin–none Eye–slight | ||
Metribuzin | 1,090–2,300 mg/kg | Rat, 2 years 5 mg/kg Dog, 2 years 2.5 mg/kg | Rat, rabbit >20,000 mg/kg | LC50 Bobwhite quail and Mallard duck >4,000 ppm in diet | LC50 96 hours Bluegill 80 mg/L Rainbow trout 64–76 mg/L | Skin–none Eye–none |
Napropamide | >5,000 mg/kg | Dog, 13 weeks < 100 mg/kg | Rabbit >4,640 mg/kg | LC50 5 day Bobwhite quail >5,600 ppm Mallard duck 7,200 ppm in diet | LC50 96 hours Bluegill 20–30 mg/L Rainbow trout 9–16 mg/L | Skin–none Eye–none |
Naptalam | >5,000 mg/kg 1,770 mg/kg (Na+ salt) | Rat, dog, 90 days 1,000 mg/kg (Na+ salt) | Rabbit >20,000 mg/kg | LC50 8 day Bobwhite quail 5,600 ppm Mallard duck >10,000 ppm in diet | LC50 96 hours Bluegill 354 mg/L Rainbow trout 76 mg/L | Skin–mild Eye–moderate |
Nicosulfuron | Mouse >5,000 mg/kg | Dog, 1 year >5,000 ppm in diet (M) | Rat, rabbit >2,000 mg/kg | LC50 Bobwhite quail and Mallard duck >5,620 ppm in diet | LC50 96 hours Bluegill and Rainbow trout >1,000 mg/L | Skin–none Eye–moderate |
Oxadiazon | >5,000 mg/kg | Rat, dog, 2 years 100 mg/kg | Rabbit >2,000 mg/kg | LC50 Bobwhite quail and Mallard duck >5,620 ppm in diet | LC50 96 hours Bluegill 12.5 mg/L Rainbow trout 2 mg/L | Skin–moderate Eye–mild |
Oxyfluorfen | Rat, dog >5,000 mg/kg | Rat, 2 years 2 mg/kg Dog, 2.5 mg/kg | Rabbit >5,000 mg/kg | LC50 Bobwhite quail >5,000 Mallard duck >4,000 ppm in diet | LC50 96 hours Bluegill 0.2 mg/L Rainbow trout 0.41 mg/L | Skin–none Eye–moderate |
Paraquat (dichloride) | 150–283 mg/kg | Rat, 2 years 1.25 mg/kg Dog, 1 year 0.45 mg/kg | Rat >2,000 mg/kg (finished product) | LC50 5 day Bobwhite quail 981 ppm Mallard duck 4,048 ppm in diet | LC50 96 hours Rainbow trout 26 mg/L | Skin–slight Eye–moderate |
Pebulate | 1,120 mg/kg | Rat, 2 years 15 ppm in diet (eye lesions) | Rabbit 4,640 mg/kg | LC50 Bobwhite quail and Mallard duck >2,400 ppm in diet | LC50 96 hours Bluegill and Rainbow trout 7.4 mg/L | Skin–slight Eye–mild |
Pendimethalin | 1,050 to >5,000 mg/kg | Dog, 2 years 12.5 mg/kg/day | Rabbit >5,000 mg/kg | LC50 8 day Bobwhite quail 3,149 ppm Mallard duck 10,900 ppm in diet | LC50 96 hours Bluegill 0.199 mg/L Rainbow trout 0.138 mg/L | Skin–none Eye–mild |
Phenmedipham | 8,000 mg/kg | Dog, 2 years >1,000 ppm in diet | Rat >2,000 mg/kg Rabbit >10,000 mg/kg | LC50 4 day Bobwhite quail >2,480 ppm in diet | LC50 96 hours Bluegill 760 mg/L LC50 21 day Rainbow trout >210 mg/L | Skin–moderate Eye–severe |
Picloram | 5,000–8,200 mg/kg | Rat, 2 years 150 mg/kg/day | Rabbit >4,000 mg/kg | LD50 8 day Bobwhite quail >2,500 Mallard duck >5,000 mg/kg | LC50 96 hours Bluegill 14.5 mg/L Rainbow trout 19.3 mg/L | Skin–mild Eye–moderate |
Prometryn | 3,750–5,235 mg/kg | Dog, 90 days < 200 ppm in diet | Rabbit >2,000 mg/kg | LC50 5–7 day Bobwhite quail and Mallard duck >10,000 ppm in diet | LC50 96 hours Bluegill 10 mg/kg Rainbow trout 2.5–2.9 mg/L | Skin–none Eye–slight |
Propanil | 1,080 to >2,500 mg/kg | Dog, 2 years < 85 ppm in diet | Rabbit >5,000 mg/kg | LC50 8 day Bobwhite quail 2,861 ppm Mallard duck 5,627 ppm in diet | LC50 96 hours Bluegill 2.3 mg/L Rainbow trout 4.6 mg/L | Skin–moderate Eye–serious |
Propoxycarbazone | >5,000 mg/kg | Dog, 1 year 258 mg/kg (M) 55.7 mg/kg (F) | Rat >5,000 mg/kg | Skin–slight Eye–minimal | ||
Propyzamide | 5,620–8,350 mg/kg | Dog, 2 years >7.5 ppm in diet | Rabbit 3,160 mg/kg | LC50 8 day Bobwhite quail and Mallard duck >10,000 ppm in diet | LC50 96 hours Bluegill 100 mg/L Rainbow trout 72 mg/L | Skin–slight Eye–moderate |
Pyrazon | 3,030–3,600 mg/kg | Dog, 2 years 1,500 ppm in diet | Rat >2,000 mg/kg | LC50 Bluegill 40 mg/L | Skin–slight Eye–slight | |
Pyridate | 1,285–1,412 mg/kg | Dog, 1 year 30 mg/kg/day | Rabbit >2,000 mg/kg | LC50 8 day Bobwhite quail >5,000 ppm in diet | LC50 96 hours Rainbow trout >1.2 mg/L | Skin–none Eye–slight |
Pyrithiobac-sodium | 4,000 mg/kg | Rat (longterm), 59 mg/kg | Rat >2,000 mg/kg | LC50 Bobwhite quail and Mallard duck >6,300 ppm | LC50 96 hours Bluegill 5.8 mg/L Rainbow trout 8.2 mg/L | Skin–mild Eye–moderate |
Quinclorac | 3,060 mg/kg (M) 2,190 mg/kg (F) | Dog, 1 year 142 mg/kg/day (M) 140 mg/kg/day (F) | Rat >2,000 mg/kg | LD50 Bobwhite quail and Mallard duck >5,000 mg/kg | LC50 96 hours Bluegill and Rainbow trout >100 mg/L | Skin–irritating Eye–moderate |
Quizalofop-p-ethyl | 1,210–1,670 mg/kg (M) 1,182–1,480 mg/kg (F) | Dog, 1 year < 10 mg/kg/day | Rat, mouse, rabbit >10,000 mg/kg | LC50 8 day Bobwhite quail and Mallard duck >5,000 ppm in diet | LC50 96 hours Bluegill 0.46–2.8 mg/L Rainbow trout 10.7 mg/L | Skin–none Eye–slight |
Rimsulfuron | >5,000 mg/kg | Dog, 1 year 50 ppm in diet | Rabbit >2,000 mg/kg | LC50 8 day Bobwhite quail >5,620 ppm Mallard duck >2,510 ppm in diet | LC50 96 hours Bluegill 100 mg/L Rainbow trout 32 mg/L | Skin–mild Eye–mild |
Sethoxydim | 3,200 mg/kg (M) 2,676 mg/kg (F) | Dog, 1 year >8.86 mg/kg (M) >9.41 mg/kg (F) | Rat, mouse >5,000 mg/kg | LC50 8 day Bobwhite quail and Mallard duck >5,600 ppm in diet | LC50 96 hours Bluegill and Rainbow trout >1,000 mg/L | Skin–none Eye–moderate |
Siduron | >7,500 mg/kg | Rat, 2 years 500 ppm in diet | Rabbit >5,500 mg/kg | LC50 Bobwhite quail and Mallard duck >10,000 mg/kg | LC50 48 hours Crucian carp 18 mg/L | Skin–slight Eye–slight |
Simazine | >5,000 mg/kg | Rat, 2 years >5 mg/kg/day | Rabbit >10,200 mg/kg | LC50 8 day Bobwhite quail >5,260 ppm Mallard duck 10,000 ppm in diet | LC50 96 hours Bluegill and Rainbow trout >100 mg/L | Skin–none Eye–none |
Sodium chlorate | 1,200–7,000 mg/kg | Rabbit 500 mg/kg | LC50 48 hours Fish 10,000 mg/L | Skin–moderate Eye–moderate | ||
Sulfentrazone | 2,416–3,297 mg/kg | Rat, 10 mg/kg/day (oral developmental studies) | Rat >5,000 mg/kg | LD50 Bobwhite quail and Mallard duck >5,620 ppm | LC50 96 hours Bluegill 93.8 mg/L Rainbow trout >130 mg/L | Skin–mild Eye–moderate |
Sulfosulfuron | >5,000 mg/kg | Mouse, 90 days 7,000 mg/kg of diet | Rat >5,000 mg/kg | LD50 Bobwhite quail and Mallard duck 5,620 ppm | LC50 96 hours Rainbow trout >97 mg/L | Skin–slight Eye–slight |
Tebuthiuron | 644 mg/kg | Dog, 1 year >25 mg/kg/day | Rabbit >200 mg/kg | LD50 Bobwhite quail and Mallard duck >2,500 mg/kg | LC50 96 hours Bluegill 112 mg/L Rainbow trout 144 mg/L | Skin–slight Eye–slight |
Thiazopyr | >5,000 mg/kg | Dog, 1 year 0.8 mg/kg/day | Rat >5,000 mg/kg | LD50 Bobwhite quail and Mallard duck 5,328 mg/kg | LC50 Bluegill and Rainbow trout 3.5 mg/L | Skin–slight Eye–slight |
Thifensulfuron-methyl | >5,000 mg/kg | Rat, 2 years 25 ppm in diet | Rabbit >2,000 mg/kg | LC50 8 day Bobwhite quail and Mallard duck >5,620 mg/kg | LC50 96 hours Bluegill and Rainbow trout 100 mg/L | Skin–none Eye–moderate |
Tralkoxydim | 1,258 mg/kg (M) 934 mg/kg (F) | Rat (teratogen), 30 mg/kg | Rat >2,000 mg/kg | LD50 Mallard duck >3,020 mg/kg | LC50 96 hours Bluegill >6.1 mg/L Rainbow trout >7.2 mg/L | Skin–mild Eye–mild |
Triallate | 800–2,165 mg/kg | Dog, 2 years 15 mg/kg/day (highest tested) | Rabbit 8,200 mg/kg | LC50 8 day Bobwhite quail and Mallard duck >5,000 mg/kg | LC50 96 hours Bluegill 1.3 mg/L Rainbow trout 1.2 mg/L | Skin–moderate Eye–slight |
Triasulfuron | >5,000 mg/kg | Dog, 1 year 129 mg/kg/day | Rat >2,000 mg/kg | LC50 8 day Bobwhite quail and Mallard duck >5,000 ppm | LC50 96 hours Bluegill and Rainbow trout >100 ppm | Skin–none Eye–none |
Tribenuron-methyl | >5,000 mg/kg | Dog, 1 year 875 ppm in diet | Rabbit >2,000 mg/kg | LC50 Bobwhite quail and Mallard duck >5,620 ppm | LC50 96 hours Bluegill 760 mg/L Rainbow trout 730 mg/L | Skin–none Eye–mild to moderate |
Trichloracetic acid | 3,200–5,000 mg/kg | Rat >2,000 mg/kg | LD50 Chicken 4,280 mg/kg | Not toxic to fish | Skin–severe Eye–severe | |
Triclopyr | 630–729 mg/kg | Rat, 2 years 3 mg/kg/day | Rabbit >2,000 mg/kg | LC50 8 day Bobwhite quail 2,935 ppm Mallard duck >5,401 ppm in diet | LC50 96 hours Bluegill 148 mg/L Rainbow trout 117 mg/L | Skin–none Eye–slight |
Trifluralin | >5,000 mg/kg | Dog, 2 years 18.75 mg/kg/day | Rabbit >2,000 mg/kg | LC50 8 day Bobwhite quail and Mallard duck >5,000 ppm in diet | LC50 96 hours Bluegill 0.05–0.07 mg/L Rainbow trout 0.02–0.06 mg/L | Skin–none Eye–moderate |
Vernolate | 1,200–1,900 mg/kg | Dog, 90 days >38 mg/kg/day | Rabbit >1,955 mg/kg | LC50 7 day Bobwhite quail 12,000 ppm in diet | LC50 96 hours Bluegill 8.4 mg/L Rainbow trout 9.6 mg/L | Skin–none Eye–none |
a NOAEL = No observable adverse effect level, daily dosage or ppm concentration in the diet | ||||||
b NOAEC = No observable adverse effect concentration | ||||||
c Liquid | ||||||
d Obsolete or no active registration | ||||||
e Technical grade chemical | ||||||
Oral Toxic Doses (TD) and Lethal Doses (LD) of Herbicides in Domestic Species
Compound | TD/LD | Species | Dosage (mg/kg) |
|---|---|---|---|
Phenoxy acid derivatives | |||
Phenoxy acid and its sodium salt | LD50 | Chickens | 547 |
Dogs | 100–800 | ||
LD | Pigs | 500 | |
Hens | 380–765 | ||
TD | Pigs | 100 | |
Calves | 200 | ||
Butyl glycol ester | TD | Cattle | 250 for 3 days |
Sheep | 250 for 2 days | ||
Amine salts | TD | Cattle | 250 for 10 days |
Sheep | 250 for 10 days or | ||
Sheep | 500 for 7 days | ||
Bipyridyl compounds or quaternary ammonium | |||
Paraquat | LD50 | Dogs | 25–50 |
Cats | 35 | ||
Monkeys | 50–70 | ||
Cattle | 35–50 | ||
Chickens | 110–360 | ||
LD | Sheep | 8–10 | |
Pigs | 75 | ||
Diquat | LD50 | Dogs | 100–200 |
Cats | 35–50 | ||
Cattle | 20–40 | ||
Chickens | 200–400 | ||
Ureas and thioureas | |||
Diuron | TD | Cattle | 100 for 10 days |
Sheep | 250 or 100 for 2 days | ||
Chickens | 50 for 10 days | ||
Linuron | TD | Dogs | 100–200 |
Cats | 35–50 | ||
Cattle | 20–40 | ||
Chickens | 200–400 | ||
Tebuthiuron | LD50 | Cats | >200 |
TD | Cats | 200 | |
LD50 | Dogs | >500 | |
TD | Dogs | 50/day for 3 moa | |
Chickens, quail, or ducks | No deaths were reported at a dosage of 500 mg/kg body wt. | ||
Protoporphyrinogen oxidase inhibitors | |||
Metribuzin | LD50 | Cats | >500 |
Anilide, acetamides, or amide compounds | |||
Propanil | LD50 | Dogs | 1,217 |
Propyzamide | LD50 | Dogs | >10,000 |
Dinitrophenolic compounds | |||
DNOC | LD50 | Hens | 26 |
Dogs | 50 | ||
Pigs | 50 | ||
Goats | 100 | ||
TD | Cattle | 2–50 | |
Sheep | 20–50 | ||
LD | Sheep | 25 for 5 days | |
Dinoseb | LD50 | Hens | 26 |
TD | Cattle | 25 for 8 days | |
Sheep | 25 for 10 days | ||
Dinitroaniline | |||
Bromacil | |||
TD | Cattle | 250 | |
Chickens | 500 for 10 days | ||
Sheep | 50 for 10 days or 250 for 8 days | ||
Trifluralin | LD50 | Dogs | >2,000 |
Carbamates and thiocarbamate compounds | |||
Asulam | LD50 | Rabbits | >2,000 |
Chickens | >2,000 | ||
Dogs | >5,000 | ||
Di-allate | LD50 | Dogs | 510 |
TD | Chickens | 150 for 10 days or 250 for 7 days | |
Cattle | 25 for 5 days or 50 for 3 days | ||
Sheep | 25 for 5 days or 50 for 3 days | ||
Phenmedipham | LD50 | Dogs | >4,000 |
LD50 | Chickens | >3,000 | |
Picloram | LD50 | Cattle | >750 |
Sheep | >1,000 | ||
Picrolinic acid derivative | |||
a Anorexia and weight loss reported. No deaths were reported in dogs at a tebuthiuron dosage of 500 mg/kg body wt. | |||
Herbicides with Potential to Cause Developmental Toxicity in Experimental Animals
Compound | Effects |
|---|---|
Atrizine | Disruption of ovarian cycle and induced repetitive pseudopregnancy (rats, at high doses) |
Buturon | Cleft palate, increased fetal mortality (mice) |
Butiphos | Teratogenic (rabbit) |
Chloridazon | Malformations |
Chlorpropham | Malformations or other developmental toxicity (mice) |
Cynazine | Malformations such as cyclopia and diaphragmatic hernia (rabbits); skeletal variations in rats |
2,4-Da or 2,4,5-Ta alone or in combination | Malformations such as cleft palate, hydronephrosis; teratogenic (mice, rats) |
Dichlorprop | Teratogenic (mice); affect postnatal behavior (rats) |
Dinosebb | Multiple defects (mice, rabbits) |
Dinoterb | Skeletal malformations (rats); skeletal, jaw, head, and visceral (rabbits) |
Linuron | Malformations (rats) |
Mecoprop | Malformations (mice only) |
Monolinuron | Cleft palate (mice) |
MCPAc | Teratogenic and embryotoxic (rats), teratogenic (mice) |
Prometryn | Head, limbs, and tail defects (rat) |
Propachlor | Slightly teratogenic (rats) |
Nitrofenb | Malformations (mice, rats, hamsters) |
Silvex | Teratogenic (mice) |
TCDDa | Malformations/teratogenic (fetotoxicity in chickens, rats, mice, rabbits, guinea pigs, hamsters, and monkeys) |
Tridiphane | Malformations such as cleft palate (mice); skeletal variations (rats) |
a TCDD is a common contaminant during the manufacturing process of some herbicides such as 2,4-D and 2,4,5-T. | |
b Obsolete | |
c 2-methyl-4-chlorophenoxyacetic acid | |
There are >200 active ingredients used as herbicides; however, some of them are believed to be obsolete or no longer in use. Of these, several have been evaluated for their toxic potential and are discussed below. More specific information is available on the label and from the manufacturer, cooperative extension service, or poison control center. Selected information on herbicides, such as the acute oral toxic dose (LD50) in rats, the amount an animal can be exposed to without being affected (no adverse effect level), the likelihood of problems caused by dermal contact in rabbits (dermal LD50, eye and skin irritation), deleterious effects on avian species, and toxicity to fish in water, is included for some commonly used herbicides ( see Table: Herbicide Poisoning). Comparative toxic doses (TD) and lethal doses (LD) of selected herbicides in domesticated species, such as monkeys, cattle, sheep, pigs, cats, dogs, and chickens, is also summarized ( see Table: Oral Toxic Doses (TD) and Lethal Doses (LD) of Herbicides in Domestic Species). The information is only a guideline, because the toxicity of herbicides may be altered by the presence of other ingredients (eg, impurities, surfactants, stabilizers, emulsifiers) present in the compound. With a few exceptions, most of the newly developed chemicals have a low order of toxicity to mammals. However, some herbicides, such as atrazine, buturon, butiphos, chloridazon, chlorpropham, cynazine, 2,4-D and 2,4,5-T alone or in combination, dichlorprop, dinoseb, dinoterb, linuron, mecoprop, monolinuron, MCPA (2-methyl-4-chlorophenoxyacetic acid), prometryn, propachlor, nitrofen, silvex, TCDD (a common contaminant during manufacturing process of some herbicides such as 2,4-D and 2,4,5-T), and tridiphane, are known to have adverse effects on development of embryos and reproduction abnormalities in experimental animals. A list of such chemicals is summarized in the table .
Bioherbicides
Bioherbicides consist of phytotoxins, pathogens, and other microbes used as biologic weed control. Bioherbicides may be compounds and secondary metabolites derived from microbes such as fungi, bacteria, or protozoa or from phytotoxic plant residues, extracts, or single compounds derived from other plant species. Although 13 different products have been launched, currently only 9 bioherbicides are marketed globally. A few of the common biopesticides include Devine®, Collego®, BioMal®, Woad Warrior®, Chontrol®, Smolder®, Sarritor®, Organo-Sol®, and Beloukha®. Efficiency and efficacy of bioherbicides is impeded by changing weather and temperature, and this can further obstruct the application and integration of bioherbicides. Also, even after their "discovery," some bioherbicides are not readily available on the market for various reasons.
For More Information
Also see pet health content regarding poisoning.
