Inhalation Toxicity of Phosphine for Fischer 344 Rats and B6C3F1 Mice

Safety of Natural Insecticides: Toxic Effects on Experimental Animals

Long-term application and extensive use of synthetic insecticides have resulted in accumulating their residues in food, milk, water, and soil and cause adverse health effects to human and ecosystems. Therefore, application of natural insecticides in agriculture and public health sectors has been increased as alternative to synthetic insecticides. The question here is, are all natural insecticides safe. Therefore, the review presented here focuses on the safety of natural insecticides. Natural insecticides contain chemical, mineral, and biological materials and some products are available commercially, e.g., pyrethrum, neem, spinosad, rotenone, abamectin, Bacillus thuringiensis (Bt), garlic, cinnamon, pepper, and essential oil products. It can induce hepatotoxicity, renal toxicity, hematotoxicity, reproductive toxicity, neurotoxicity, and oxidative stress. It can induce mutagenicity, genotoxicity, and carcinogenicity in mammals. Some natural insecticides and active compounds from essential oils are classified in categories Ib (Highly hazardous) to U (unlikely toxic). Therefore, the selectivity and safety of natural insecticides not absolute and some natural compounds are toxic and induce adverse effects to experimental animals. In concussion, all natural insecticides are not safe and the term "natural" does not mean that compounds are safe. In this respect, the term "natural" is not synonymous with "organic" and not all-natural insecticide products are acceptable in organic farmers.

Worker exposure standard for phosphine gas

The 1998 U.S. Environmental Protection Agency Office of Pesticide Programs (OPP) re-registration eligibility decision (RED) for phosphine fumigants has generated much interest in defining safe levels of exposure for workers and worker bystanders. This report summarizes the pertinent literature on phosphine toxicity, including animal inhalation studies and human epidemiology studies, and also describes a margin-of-exposure (MOE) analysis based on available worker exposure data. In addition, a safe occupational exposure limit is estimated using typical OPP assumptions, after determination of appropriate uncertainty factors, based on quality of data in the principal study and pharmacokinetic considerations. While a conservative 8-hour time-weighted average (TWA) of 0.1 ppm was calculated, the overall weight of evidence, from a risk-management perspective, supports a conclusion that an occupational TWA of 0.3 ppm provides adequate health protection. In addition, a 15-minute short-term exposure limit (STEL) of 3 ppm was estimated. Finally, in contrast to the MOE analysis described in the OPP's phosphine RED, the MOE analysis described herein does not indicate that fumigation workers are currently being exposed to unacceptable levels of phosphine. Collectively, these findings support the occupational exposure limits of 0.3 ppm (8-hour TWA) and 1 ppm (STEL) established in the updated applicator's manuals for phosphine-generating products, which recently received approval from OPP.