Human risks can include;

Allergic/ toxic reactions (to hidden genes and combination)
Antibiotic resistance
Immune - suppression
Increased cancer risk
Unsuspected side effects

Environmental impacts can include;

Uncontrolled biological pollution
Threatening numerous microbial, plant and animal species with extinction.
Potential contamination of non-genetically engineered life forms with novel and possibly hazardous genetic material.
Increased use of and dependence on toxic herbicides.
Harm to farming (deformed crops, increased pest resistance, increased farmer costs and debt).
Crop failures.
Biodiversity (implications for biodiversity, the balance of wildlife and the environment).
Creation of GM "Superweeds" and "Superpests".
Damage to food quality and nutrition.
Ethical Issues

How to avoid GMO

The only guaranteed way to avoid eating GMOs is to buy fresh certified organic produce.
Read labels - When buying a product check the ingredients on the label. GM soybean and corn make up the largest portion of GE crops. If they are listed then there is a good chance it is GM. Remember the label does not have to declare that it contains GM ingredients.
Avoid processed foods - 70% of processed foods contain GM ingredients.

Australia and GMO

Australia is already commercially producing GE cotton. This cotton is known as BT cotton as it produces a genetically engineered toxin called Bacillus Thuringensis (BT). Bt cotton produces this toxin in every part of the plant so that the cotton plant itself becomes a pesticide factory. Bt cotton is not only used for cloth and cotton products but the cottonseed is crushed for oil used in food.

Australia is also commercially growing GE canola, carrying on trials of GE wheat and growing GE blue carnation flowers.

The major problem remains that genetic engineering is highly unpredictable and that the "jury is still out" as to what impact GMO crops will have on human beings and on the environment!