Ochratoxin A in airborne dust and fungal conidia.

Farm workers are often exposed to high concentrations of airborne organic dust and fungal conidia, especially when working with plant materials. The purpose of this investigation was to study the possibility of exposure to the mycotoxin ochratoxin A (OTA) through inhalation of organic dust and conidia. Dust and aerosol samples were collected from three local cowsheds. Aerosol samples for determination of total conidia and dust concentrations were collected by stationary sampling on polycarbonate filters. Total dust was analysed by gravimetry, and conidia were counted using scanning electron microscopy. A method was developed for extraction and determination of OTA in small samples of settled dust. OTA was extracted with a mixture of methanol, chloroform, HCl, and water, purified on immunoaffinity column, and analysed by ion-pair HPLC with fluorescence detection. Recovery of OTA from spiked dust samples (0.9-1.0 microg/kg) was 74% (quantitation limit 0.150 microg/kg). OTA was found in 6 out of 14 settled dust samples (0.2-70 microg/kg). The total concentration of airborne conidia ranged from < 1.1 x 10(4) to 3.9 x 15(5) per m3, and the airborne dust concentration ranged from 0.08 to 0.21 mg/m3. Conidia collected from cultures of Penicillium verrucosum and Aspergillus ochraceus contained 0.4-0.7 and 0.02-0.06 pg OTA per conidium, respectively. Testing of conidial extracts from these fungi in a Bacillus subtilis bioassay indicated the presence of toxic compounds in addition to OTA. The results show that airborne dust and fungal conidia can be sources of OTA. Peak exposures to airborne OTA may be significant, e.g., in agricultural environments.

Presence of ochratoxin A in human milk in relation to dietary intake.

Individual and geographical variations in ochratoxin A (OA) levels in human blood and milk samples may be due to differences in dietary habits. The purpose of this study was to examine the relationship between OA contamination of human milk and dietary intake. Human milk samples were collected from 80 Norwegian women. The usual food intake during the last year was recorded using a quantitative food frequency questionnaire. The concentration of OA in the human milk was determined by HPLC (detection limit 10 ng/l). Seventeen (21%) out of 80 human milk samples contained OA in the range 10-182 ng/l. The women with a high dietary intake of liver paste (liverwurst, liver pâté) and cakes (cookies, fruitcakes, chocolate cakes, etc.) were more likely to have OA-contaminated milk. The risk of OA contamination was also increased by the intake of juice (all kinds). In addition, the results indicate that breakfast cereals, processed meat products, and cheese could be important contributors to dietary OA intake. OA contamination of the milk was unrelated to smoking, age, parity, and anthropometric data other than body weight.

Analysis of Norwegian milk and infant formulas for ochratoxin A.

Samples of organic cow's milk, conventional cow's milk, and cow's milk-based infant formulas were analysed for the occurrence of ochratoxin A by means of an HPLC method. The detection limit was 10 ng/l. Ochratoxin A was detected in 6 out of 40 conventional cow's milk samples (range 11-58 ng/l), and in 5 out of 47 organic milk samples (range 15-28 ng/l). No ochratoxin A was detected in any of the 20 infant formula samples. The ochratoxin A levels in cow's milk found in this investigation are sufficient to cause a higher intake of ochratoxin A than the suggested TDI of 5 ng/kg bw/day, e.g. in small children who consume large quantities of milk.

Ochratoxin A: a naturally occurring mycotoxin found in human milk samples from Norway.

The presence of ochratoxin A (OA) in human milk samples from different regions in Norway was investigated to determine the level of infant exposure to OA from human milk. OA was found in 38 (33%) of 115 human milk samples (range 10-130 ng l(-1)). It was found that 2-26% of the samples contained more than 40 ng l(-1) OA, which will cause a daily intake of OA from human milk exceeding the suggested tolerable dose of 5 ng kg(-1) body weight. Significant regional differences were found.