Now’s the time to do an inventory and safely dispose of these items to be sure nothing that could threaten your family or pets is still lingering. To help you know what to look for, here’s our list of killers masquerading as household helpers. If you find any of these chemicals, contact the hazardous waste collection agency in your town, city or state to learn how to handle them and make sure you don’t harm yourself or the environment in trying to get rid of them.

Strychnine

Rodenticides Strychnine might be the most famous name on this list; rumored, fictional, or documented cases of death by strychnine poisoning include Alexander the Great, blues legend Robert Johnson, and two characters from Psycho. And it’s not an easy way to go, either. Ingesting this rodenticide has several gruesome stages. First, severe nausea and vomiting can occur; next, convulsions begin, lasting longer and occurring more frequently as the chemical courses through your system. If you survive the violent seizures, you’ll end up in a rigor-mortis-like muscle lockdown, leading to death by asphyxiation.

Lye (sodium hydroxide)

Drain cleaners This highly caustic alkaline chemical cures fish and olives, straightens hair, and bleaches wood faster than you can say “Ow! That stuff really burns!” But unless your house’s previous owner had a taste for Scandinavian lutefisk, lye would probably be lying around for one reason: drain cleaning. While the chemical is legal, it’s still as dangerous as ever—especially if moisture hits the dry, granulated version. Inhaling lye fumes can cause your throat to swell, inflame your lungs, and also affect your esophagus. It can also burn skin on contact or blind you if it gets in your eyes; if ingested, it can eat holes in the digestive tract and even induce a coma.

Perfluorooctane sulfonate (PFOS)

Old formulations of Scotchgard This miracle product was developed in the early 1950s, when a 3M scientist spilled some synthetic latex onto her white tennis shoes and found that it prevented further staining. PFOS became the darling of the upholstery and carpet industries for decades. Fabrics and carpets were impregnated with it at the plant, and clean-freak homeowners could buy the stuff in spray-on form in a can. In 2000, however, 3M announced it would phase out PFOS production because tests showed the chemical had a strong tendency to accumulate in human tissue and could pose a health risk. Health activists suspect that PFOS causes cancer and liver damage, and increases the risk of high cholesterol, thyroid-related health problems, and the likelihood of attention deficit hyperactivity disorder (ADHD) in children, though the Centers for Disease Control has not yet found a link to these issues. Nevertheless, the company has since brought a non-PFOS version of its product back on the market, one with a chemical half-life of weeks instead of years.

Lead

Lead paint The federal government banned the sale of lead paint in 1978 because it can cause kidney and reproductive problems in adults and, worse, physical and mental developmental issues in children. After more than three decades, it’s likely that the half-used can you found in the garage has dried out. But if you unearth an untouched gallon sitting on a back shelf, resist the urge to use it, even for a small project. More important, find out how to dispose of it properly in your municipality; don’t just throw it away. And if you realize the same shade of blue on the can is the one in that now-peeling kids’ bedroom, buy a lead-testing kit and look up the number of a certified abatement specialist. Contractors doing painting or remodeling are now required by federal law to get training in preventing lead contamination and must follow strict demolition and disposal guidelines, so getting rid of the stuff in places where the dust can get to children is a job best left to the pros.

Dichloro-diphenyl-trichloroethane (DDT)

DDT-based pesticides Concerned that the worldwide use of DDT in agriculture, home gardens, and infectious-disease prevention without much research into the effects of the chemical was the real cause of mass bird deaths, American biologist Rachel Carson wrote Silent Spring in 1962. The seminal book set off investigations that led to a 1972 ban on the chemical, which is suspected of being a carcinogen and is known to have adverse effects on pregnancy and growth. Forty years later DDT may seem like a long-lost product, but finding some of the old pesticide in your garden shed isn’t totally out of the realm of possibility: as late as 2006, one homeowner brought a 50-pound bag of the pesticide to cleanup authorities.

Diazinon

Diazinon pesticides Diazinon is a lethal way to take out cockroaches, ants, and fleas; it inhibits the enzymes necessary for proper functioning of the nervous system—and it works the same way on humans. Weakness, headaches, tightness in the chest, sweating, nausea, vomiting, and slurred speech are only a few of the symptoms of diazinon exposure. The pesticide was most popular in the 1970s and 1980s for use in home gardens but was outlawed in 2004 for residential use—though it’s still legal to use products containing diazinon bought before the 2004 ban.

Chlorpyrifos

Dursban Chlorpyrifos, commonly sold under the trade name Dursban, was until recently one of the most widely used pesticides in the United States. The loose form of this organophosphate insecticide, which is related to nerve gas, was pulled from the residential market in 2000 after it was linked to asthma and reproductive problems, among other issues. (It’s still used in contained bait traps.) Chlorpyrifos can send the nervous system into overdrive, leading to nausea, dizziness, confusion, and, at high exposures, respiratory paralysis and death. Though it is no longer sold to consumers, Dursban and its ilk are still allowed for commercial agricultural use in the U.S., and are sold overseas.

Creosote

Creosote, coal-tar creosote, coal-tar pitch Coal-tar creosote is a greasy black liquid used as a wood preservative. Before the advent of pressure-treated wood, it was available from hardware stores for consumers looking to weather-seal their fences and mailbox posts. Both the International Agency for Research on Cancer and the EPA have determined that the coal-tar version of creosote is a carcinogen. Eating food or drinking water contaminated with it can cause burning in the mouth and throat, and stomach pains; contact can cause rashes, chemical burns on the eyes, convulsions, kidney or liver problems, and death. And take note: Even if you don’t have a can of the stuff lurking in the basement, it might be coating the old railroad ties the previous owner used to build a raised vegetable garden.

Trisodium Phosphate (TSP)

Old formulations of cleaning solutions, household-cleaner additive Up until the 1960s, TSP was the key ingredient in most household cleaning solutions, especially for tough jobs like cleaning siding and concrete. It has been banned in many states but is still sold in some places as a degreaser. TSP is also sold as an additive for cleaning products because it is no longer included in modern formulations. In fact, the EPA still recommends the product for removing lead paint dust because it binds with lead and turns it into lead phosphate—though lead phosphate is now under scrutiny as a possible carcinogen. But mainly ecological concerns have led to a decrease in the use of TSP; phosphates, the main ingredient in fertilizer, can lead to the depletion of oxygen levels in water. In humans, concentrated amounts of the chemical cause difficulty breathing, swell the throat, can lead to vision loss, and can burn the skin.

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