Uptake of arsenic species by turnip (Brassica rapa L.) and lettuce (Lactuca sativa L.) treated with roxarsone and its metabolites in chicken manure

Roxarsone is an organoarsenic feed additive that can be metabolised to other higher toxic arsenic (As) species in animal manure such as arsenate, arsenite, monomethylarsonic acid, dimethylarsinic acid, 3-amino-4-hydroxyphenylarsonic acid and other unknown As species. The accumulation, transport and distribution of As species in turnip (Brassica rapa L.) and lettuce (Lactuca sativa L.) amended with roxarsone and its metabolites in chicken manure were investigated. Results showed arsenite was the predominant As form, followed by arsenate in turnip and lettuce plants, and a low content of dimethylarsinic acid was detected only in lettuce roots. Compared with the control plants treated with chicken manure without roxarsone and its metabolites, the treatments containing roxarsone and its metabolites increased arsenite content by 2.0-3.2% in turnip shoots, by 6.6-6.7% in lettuce shoots, by 11-44% in turnip tubers and by 18-20% in lettuce roots at two growth stages. The enhanced proportion of arsenate content in turnip shoots, turnip tubers and lettuce roots was 4.3-14%, 20-35% and 70%, respectively, while dimethylarsinic acid content in lettuce roots increased 2.4 times. Results showed that the occurrence of dimethylarsinic acid in lettuce roots might be converted from the inorganic As species and the uptake of both inorganic and organic As compounds in turnip and lettuce plants would be enhanced by roxarsone and its metabolites in chicken manure. The pathway of roxarsone metabolites introduced into the human body via roxarsone → animal → manure → soil → crop was indicated.

Light and electron microscopic lesions in peripheral nerves of broiler chickens due to roxarsone and lasalocid toxicoses

This paper characterizes the light microscopic and ultrastructural lesions in peripheral nerves caused by feeding lasalocid and roxarsone to broiler chickens. The birds were given three different doses of each compound: the standard industrial dose, 150% of the standard dose, and 200% of the standard dose. It was necessary to deprive the birds of water for 4 hours daily and heat-stress them in order to reproduce the lesion. Each compound caused mild microscopic lesions of swollen axons, digestion chambers, shrunken axons, or vacuoles where axons were missing. Ultrastructural changes included formation of myelin ellipsoids, vacuoles within or beneath the myelin sheath, and unraveling of myelin. These lesions were most frequently found in the birds receiving lasalocid.