Chloramphenicol is a broad-spectrum antibiotic that was first isolated from Streptomyces venezuelae in 1947. The drug was subsequently chemically synthesized. It has both a bacteriostatic and bactericidal effect; in the usual therapeutic concentrations it is bacteriostatic. Chloramphenicol is used for the treatment of serious gram-negative, gram-positive, and anaerobic infections. It is especially useful in the treatment of meningitis, typhoid fever, and cystic fibrosis. It should be reserved for infections for which other drugs are ineffective or contraindicated. Chloramphenicol, a small inhibitor of bacterial protein synthesis, is active against a variety of bacteria and readily enters the CSF. It has been used extensively in the last decades for the treatment of bacterial meningitis. In industrialized countries, chloramphenicol is restricted mostly to topical uses because of the risk of induction of aplastic anemia. However, it remains a valuable reserve antibiotic for patients with allergy to β-lactam antibiotics or with CNS infections caused by multiresistant pathogens.

Nitrofurazone is used to treat burns that have become infected. It is also used to treat skin infections due to skin grafts. It works by killing bacteria or preventing their growth. The exact mechanism of action is unknown. Nitrofurazone inhibits several bacterial enzymes, especially those involved in the aerobic and anaerobic degradation of glucose and pyruvate. The severe or irreversible adverse effects of Nitrofurazone, which give rise to further complications include Peripheral neuropathy, Thromboembolic disorder.

Chloral is a chlorinated aldehyde that found extensive use, beginning in the 1940s, as a precursor in the production of the insecticide DDT and, to a lesser extent, of other insecticides and pharmaceuticals. This use of chloral has declined steadily since the 1960s, especially in those countries where the use of DDT has been restricted. Chloral is readily converted to chloral hydrate in the presence of water. Chloral hydrate is used as a sedative before medical procedures and to reduce anxiety related to withdrawal from drugs. Wider exposure to chloral hydrate occurs at microgram-per-liter levels in drinking water and swimming pools as a result of chlorination. Chloral hydrate is a well-established aneuploidogenic agent that also has some mutagenic activity. In human cells in vitro, chloral hydrate induced aneuploidy, micronuclei and gene mutations. Chloral hydrate clearly induced micronuclei in Chinese hamster cells, whereas findings in mouse lymphoma cells were conflicting. Induction of somatic mutation (but not sex-linked mutation) by chloral hydrate was demonstrated in insects. Chloral hydrate is metabolized in vivo to trichloroethanol, which is responsible for its physiological and psychological effects. The metabolite of chloral hydrate exerts its pharmacological properties via enhancing the GABA receptor complex and therefore is similar in action to benzodiazepines, nonbenzodiazepines, and barbiturates. In clinical studies, oral chloral hydrate appears to have a lower sedation failure rate when compared with oral promethazine for children undergoing pediatric neurodiagnostic procedures. The sedation failure was similar for other comparisons such as oral dexmedetomidine, oral hydroxyzine hydrochloride, and oral midazolam. When compared with intravenous pentobarbital and music therapy, oral chloral hydrate had a higher sedation failure rate. Compared to dexmedetomidine, chloral hydrate was associated with a higher risk of nausea and vomiting.

Ethyl chloride is a colourless flammable gas at ordinary temperature and pressure. It has a characteristic ether-like odour and a burning taste. Ethyl chloride is used as a chemical intermediate, in solvents, aerosols, and anaesthesia. Currently, chloroethane is largely used as a blowing agent in foamed plastics. In the past, chloroethane was used in the production of tetraethyl lead, an anti-knock additive to leaded gasoline. Chloroethane has also been used in the production of ethyl cellulose and for miscellaneous applications including use as a solvent, for phosphorus, sulfur, fats, oils, resins and waxes; in insecticides; and as an ethylating agent in the manufacture of dyes and drugs, refrigerant, and topical anaesthetic and use in the manufacture of dyes, chemicals, and pharmaceuticals. Other uses of chloroethane are as a pulp vitality tester in dentistry, as a medication to alleviate pain associated with insect burns and stings, as an adjunct in the treatment of tinea lesions and creeping eruptions, and as a counterirritant for relief of myofacial and visceral pain syndromes. Chloroethane is also used as a solvent, as a refrigerant, and in the production of ethyl cellulose, dyes, medicinal drugs, and other commercial chemicals. It is also used to numb skin prior to medical procedures such as ear piercing and skin biopsy, and in sports injuries.

Formaldehyde is a naturally occurring organic compound, and an important industrial precursor to many other materials and organic compounds. Formaldehyde solution (formalin) is used as a disinfectant. Formaldehyde vapors are toxic, upon entry formaldehyde reacts readily with macromolecules, including DNA to form DNA-protein and DNA-DNA cross-links.

Cacodylic acid also known as dimethylarsinic acid (DMA) has been used as a herbicide. As a part of agent blue it used to destroy broadleaf plants and trees, especially rice paddies during the Vietnam War. DMA is the major metabolite formed after exposure to tri- (arsenite) or pentavalent (arsenate) inorganic arsenic (iAs) via ingestion or inhalation in both humans and rodents. DMA induces an organ-specific lesion--single strand breaks in DNA. Mechanistic studies have suggested that this damage is due mainly to the peroxyl radical of DMA and production of active oxygen species by pulmonary tissues. Multi-organ initiation-promotion studies have demonstrated that DMA acts as a promotor of urinary bladder, kidney, liver and thyroid gland cancers in rats and as a promotor of lung tumors in mice. Thus it was shown, that DMA played a role in the carcinogenesis of inorganic arsenic.

Phenacetin was used as an analgesic and fever-reducing drug in both human and veterinary medicine for many years. Since a major portion of a dose of phenacetin is rapidly metabolised to paracetamol, it seems possible that phenacetin owes some of its therapeutic activity to its main metabolite, paracetamol, whereas its most troublesome side effect (methaemoglobinaemia) is due to another metabolite, p-phenetidine. Phenacetin was shown to inhibit cyclooxygenase (COX)-3, a cyclooxygenase-1 variant while p-phenetidine potently inhibits both COX-1 and COX-2. There is sufficient evidence in humans for the carcinogenicity of analgesic mixtures containing phenacetin. Analgesic mixtures containing phenacetin cause cancer of the renal pelvis, and of the ureter. Phenacetin was withdrawn from many analgesic mixtures long before the legal ban in several countries.

Chloroform is a colorless, sweet-smelling, dense liquid and widely used industrial and laboratory solvent. The total global flux of chloroform through the environment is approximately 660 000 tonnes per year, and about 90% of emissions are natural in origin. Many kinds of seaweed produce chloroform, and fungi are believed to produce chloroform in soil. Chloroform is used as an industrial solvent and as an intermediate in the manufacture of polymeric materials. The major use of chloroformtoday is in the production of the refrigerant R-22, commonly used in the air conditioning business. Inhaled chloroform anesthesia was introduced in 1847 and Chloroform subsequently became the most widely used volatile anaesthetic, and was used in horses before the end of the 19th century. Pure chloroform is known to be decomposed by the air with the formation of hydrochloric acid, phosgene and carbon dioxide. Phosgene is also generated metabolically from chloroform, and liver and kidney damage can ensue from its production.

Allyl isothiocyanate (AITC), also known as mustard oil, is one of the most common naturally occurring isothiocyanates, which occurs in many common cruciferous vegetables. Besides antimicrobial activity against a wide spectrum of pathogens, it showed anticancer activity in both cultured cancer cells and animal models, although the underlining mechanisms remain largely undefined. Allyl isothiocyanate is a TRPA1 and TRPV1 agonist and pungency and lachrymatory effects of Allyl isothiocyanate are mediated through the TRPA1 and TRPV1 ion channels. Allyl isothiocyanate irritates the mucous membranes and induces eczematous or vesicular skin reactions.