Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Toxin combo common in fish appears capable of impairing motor skills

02.03.2004


Pups of female rats exposed to a combination of polychlorinated biphenyls (PCBs) and methylmercury (MeHg) slip and fall more often trying to maneuver on a rotating rod than do pups from non-exposed moms, scientists say.



The findings, published in the February issue of the journal Toxicological Sciences, come from a study focusing on the effects of combined exposure of the two commonly found environmental contaminants on motor function driven by the cerebellum.

"Because people are exposed to these toxicants by eating fish taken from ecosystems where these chemicals accumulate, our findings suggest that we should seriously consider the possible impact of their additive toxic effects on human health," said Susan L. Schantz, a professor of veterinary biosciences at the University of Illinois at Urbana-Champaign.


Previous laboratory studies had suggested that the two chemicals act together to impair nervous system function. A study in February’s issue of the Journal of Pediatrics found that exposure to methylmercury causes heart damage and impairs brain growth.

The new study -- pursued as part of the doctoral dissertation by Schantz’s graduate student Cindy S. Roegge -- shows that motor skills were not significantly affected by methylmercury exposure alone, but when paired with PCBs the combined effect during development dramatically impacted the pups’ skills in one of three motor tests.

The research was done for the federally funded FRIENDS Children’s Environmental Health Center, a five-institution consortium based at the College of Veterinary Medicine at Illinois. Schantz is director of FRIENDS (Fox River Environment and Diet Study), which is studying the effects of exposure to toxicants in fish being eaten in large quantities by Laotian and Hmong refugees in Green Bay and Appleton, Wis.

In the study, female rats were exposed to just PCBs or just MeHg or to both chemicals, beginning four weeks before breeding and ending when their pups were weaned. None of the female rats showed signs of toxicity, said Schantz, who also is a professor in the Neuroscience Program and psychology department at Illinois.

At birth, the pups of mothers exposed to methylmercury alone did not differ in weight from the control group. The birth weight of pups whose mothers had been exposed to just PCBs or both chemicals was slightly, but significantly, less than the control animals.

At weaning, the weight of pups exposed to PCBs was as much as 11 percent below that of control animals, while the pups in the PCB-MeHg exposure group weighed as much as 15 percent less than controls.

Two months later, one male and female pup from each litter were tested for the next four weeks on their abilities to navigate vertical ropes, parallel bars and various speeds of rotating rods. At the end, female pups whose mothers had been exposed to MeHg were slightly impaired on the rope-climbing test, while their male counterparts actually had less hind-limb slips on the parallel bars. Overall, the results of the MeHg-exposed pups were not significantly different than that of the control animals.

However, on the rotating rods the impact of exposure to both PCBs and methylmercury became clear. As the speed of the rods exceeded 25 rpm, the pups, regardless of sex, that were exposed to both toxicants during their mothers’ pregnancies slipped significantly more often than their control counterparts. Exposure to either of the chemicals alone did not significantly impact performance.

However, Schantz said, the tests showed that PCB exposure contributed more than did the methylmercury to the pups’ deficits, although the low dosage of MeHg used in the study (1.20 milligrams compared with the 2 to 18 mg used in previous studies of motor skills) may explain why.

It could be, the researchers wrote, that the chemicals have independent mechanisms of toxicity or they each act by means of the same mechanism but with greater impact together.

In addition to Schantz and Roegge, the other contributors were Illinois doctoral students Victor C. Wang and Brian E. Powers; Sherilyn Villareal, a visiting research specialist in veterinary biosciences; William T. Greenough, a professor of psychology and cell and structural biology at the Beckman Institute for Advanced Science and Technology at Illinois; and Anna Y. Klintsova, a psychology professor at Binghamton University in New York who formerly worked with Greenough at the Beckman Institute.


The U.S. Environmental Protection Agency and the National Institute of Environmental Health Sciences funded the study. The two agencies also fund the FRIENDS Children’s Environmental Health Center.

Jim Barlow | UIUC
Further information:
http://www.news.uiuc.edu/news/04/0301fishtoxin.html

More articles from Studies and Analyses:

nachricht Self-organising system enables motile cells to form complex search pattern
07.05.2019 | Westfälische Wilhelms-Universität Münster

nachricht Mouse studies show minimally invasive route can accurately administer drugs to brain
02.05.2019 | Johns Hopkins Medicine

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The hidden structure of the periodic system

The well-known representation of chemical elements is just one example of how objects can be arranged and classified

The periodic table of elements that most chemistry books depict is only one special case. This tabular overview of the chemical elements, which goes back to...

Im Focus: MPSD team discovers light-induced ferroelectricity in strontium titanate

Light can be used not only to measure materials’ properties, but also to change them. Especially interesting are those cases in which the function of a material can be modified, such as its ability to conduct electricity or to store information in its magnetic state. A team led by Andrea Cavalleri from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg used terahertz frequency light pulses to transform a non-ferroelectric material into a ferroelectric one.

Ferroelectricity is a state in which the constituent lattice “looks” in one specific direction, forming a macroscopic electrical polarisation. The ability to...

Im Focus: Determining the Earth’s gravity field more accurately than ever before

Researchers at TU Graz calculate the most accurate gravity field determination of the Earth using 1.16 billion satellite measurements. This yields valuable knowledge for climate research.

The Earth’s gravity fluctuates from place to place. Geodesists use this phenomenon to observe geodynamic and climatological processes. Using...

Im Focus: Tube anemone has the largest animal mitochondrial genome ever sequenced

Discovery by Brazilian and US researchers could change the classification of two species, which appear more akin to jellyfish than was thought.

The tube anemone Isarachnanthus nocturnus is only 15 cm long but has the largest mitochondrial genome of any animal sequenced to date, with 80,923 base pairs....

Im Focus: Tiny light box opens new doors into the nanoworld

Researchers at Chalmers University of Technology, Sweden, have discovered a completely new way of capturing, amplifying and linking light to matter at the nanolevel. Using a tiny box, built from stacked atomically thin material, they have succeeded in creating a type of feedback loop in which light and matter become one. The discovery, which was recently published in Nature Nanotechnology, opens up new possibilities in the world of nanophotonics.

Photonics is concerned with various means of using light. Fibre-optic communication is an example of photonics, as is the technology behind photodetectors and...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

 
Latest News

Uncovering hidden protein structures

18.06.2019 | Life Sciences

Monitoring biodiversity with sound: how machines can enrich our knowledge

18.06.2019 | Life Sciences

Schizophrenia: Adolescence is the game-changer

18.06.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>