A model for experimental and natural infection of early weaned pigs with Salmonella choleraesuis, the aetiologic agent of swine paratyphoid, has been developed. An oral dose of 10(8) colony forming units (cfu) of S choleraesuis caused 100 per cent infection of 10 pigs inoculated, as indicated by recovery of the challenge organism from ileocolic lymph nodes collected at necropsy seven days post challenge. Seven of the pigs were observed shedding S choleraesuis at least once post S choleraesuis challenge. The cumulative incidence of shedding was 30 per cent and was sufficient to infect four of 10 pigs exposed naturally. Oral challenges with less than 10(8) cfu S choleraesuis were less effective in infecting early weaned pigs and did not result in natural transmission.

Animals↗

PubMedDate not supplied

Respiratory toxicity of mattress emissions in mice.

Groups of male Swiss-Webster mice breathed emissions of several brands of crib mattresses for two 1-hr periods. The authors used a computerized version of ASTM-E-981 test method to monitor respiratory frequency, pattern, and airflow velocity and to diagnose abnormalities when statistically significant changes appeared. The emissions of four mattresses caused various combinations of upper-airways irritation (i.e., sensory irritation), lower-airways irritation (pulmonary irritation), and decreases in mid-expiratory airflow velocity. At the peak effect, a traditional mattress (wire springs with fiber padding) caused sensory irritation in 57% of breaths, pulmonary irritation in 23% of breaths, and airflow decrease in 11% of breaths. All mattresses caused pulmonary irritation, as shown by 17-23% of breaths at peak. The largest airflow decrease (i.e., affecting 26% of the breaths) occurred with a polyurethane foam pad covered with vinyl. Sham exposures produced less than 6% sensory irritation, pulmonary irritation, or airflow limitation. Organic cotton padding caused very different effects, evidenced by increases in both respiratory rate and tidal volume. The authors used gas chromatography/mass spectrometry to identify respiratory irritants (e.g., styrene, isopropylbenzene, limonene) in the emissions of one of the polyurethane foam mattresses. Some mattresses emitted mixtures of volatile chemicals that had the potential to cause respiratory-tract irritation and decrease airflow velocity in mice.

Air Pollutants↗

PubMedDate not supplied

Acute toxic effects of fragrance products.

To evaluate whether fragrance products can produce acute toxic effects in mammals, we allowed groups of male Swiss-Webster mice to breathe the emissions of five commercial colognes or toilet water for 1 h. We used the ASTM-E-981 test method to evaluate sensory irritation and pulmonary irritation. We used a computerized version of this test to measure the duration of the break at the end of inspiration and the duration of the pause at the end of expiration. Decreases in expiratory flow velocity indicated airflow limitation. We subjected the mice to a functional observational battery to probe for changes in nervous system function. The emissions of these fragrance products caused various combinations of sensory irritation, pulmonary irritation, decreases in expiratory airflow velocity, as well as alterations of the functional observational battery indicative of neurotoxicity. Neurotoxicity was more severe after mice were repeatedly exposed to the fragrance products. Evaluation of one of the test atmospheres with gas chromatography/mass spectrometry revealed the presence of chemicals for which irritant and neurotoxic properties had been documented previously. In summary, some fragrance products emitted chemicals that caused a variety of acute toxicities in mice.

Animals↗