Questions 31-40

Complete the notes below.

Write ONE WORD ONLY for each answer.

A CASE STUDY ON FUMIGANTS

Problems with traditional fumigation

• Some chemicals released during fumigation may damage the Earth’s 31 layer.
• After methyl bromide treatment, paintings may lose some of their original 32.
• To prevent dangerous gas from escaping, food can be placed inside a sealed 33.
• In countries with humid conditions, the treatment is often more 34 because additional equipment is required.

An alternative treatment

• Researchers created an environment containing almost no oxygen.
• The total 35 period used in the experiment lasted fourteen days.
• Air was removed from the sealed space and replaced with 36.
• The new method was tested on an old wooden 37 that had been attacked by insects.
• The treatment killed the insects without causing visible damage to the object.

A possible biological solution

• Scientists have examined protective substances found in the skin of certain 38.
• These natural chemicals behave in a similar way to 39, as they destroy harmful organisms.
• One current limitation is that the substances become less effective when exposed to 40.