Btk Questions and Answers

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1. What kind of eradication treatments have been conducted against the gypsy moth?

2. Which of the six treatments has WSDA used the most?

3. Does Btk have any disadvantages?

4. I have read several accounts on the Internet of people suffering adverse health effects after Btk treatments. Just how safe is the insecticide?

5. So Btk is not safe in every instance?

6. What common sense precautions do public health officials recommend people take after Btk treatments?

7. Why won’t WSDA release the inert ingredients of Btk?

8. What are the advantages and disadvantages of the other five eradication methods?

9. Why are so many people in general opposed to Btk?

10. Why were so many Seattle residents opposed to Btk treatments in Ballard/Magnolia in 2000 and Crown Hill neighborhood in 2002?

11. What does WSDA say to a citizen who calls and asks how they can stop a Btk treatment?

ANSWERS

Question 1: What kind of eradication treatments have been conducted against the gypsy moth?

Answer: The following six treatments are used in the US to control the gypsy moth:

1. Mass trapping, the use of small cardboard traps containing pheromones to attract male moths.
2. Mating disruptions, aerial applications of tiny plastic containers containing pheromones that attract male moths.
3. Sterile insect technique, the release of sterile male moths to confuse male moths.
4. Gypchek, a microbial insecticide.
5. Dimlin, a chemical insecticide.
6. Bacillus thuringiensis var. kurstaki (Btk), a biological insecticide found naturally in soil.

Question 2: Which of the six treatments has WSDA used the most?

Answer: Btk. The biological insecticide is a very effective eradicant. It has been used successfully on gypsy moth infestations in Washington and other states since the 1980s; has a proven safety record with people, pets, birds, fish, livestock, and other insects such as bees; has been registered and re-registered many times by the Environmental Protection Agency (EPA) for use in the U.S., to use on more than 200 food and fiber crops.

Question 3: Does Btk have any disadvantages?

Answer: Yes. The insecticide must be ingested by the gypsy moth caterpillar to be effective. Also the pesticide breaks down quickly and therefore requires three to five treatments each year to be effective, and is very sensitive to weather. Scheduled treatments are often postponed.

Question 4: I have read several accounts on the Internet of people suffering adverse health effects after Btk treatments. Just how safe is the insecticide?

Answer: Some people have reported mild skin reactions or mild eye, ear, and nose irritations after Btk treatments. Others have reported mild hay fever reactions. Health officials have studied these reports extensively and have not been able to determine if the reactions were caused by Btk or by pollens, molds, or dust generated during the treatments, or were unrelated to Btk treatments. Public health officials state Btk is not a public health risk.

Question 5: So Btk is not safe in every instance?

Answer: Nothing in science is safe in every instance. The back of our hands contain caner-producing agents in very, very low numbers. Health officials state the risk to human health from Btk is very, very low.

Question 6: What common sense precautions do public health officials recommend people take after Btk treatments?

Answer: Remain indoors for at least 30 minutes after a spray application, particularly those with leukemia, HIV, respiratory disorders, other immune deficiencies, those receiving radiation or chemotherapy, those with allergies, and those prone to respiratory irritation. Children should wait until moisture from the spray and dew has dried on grass and shrubs before playing outside. If you come in contact with the wet spray, wash the affected skin with soap and water.

Question 7: Why won’t WSDA release the inert ingredients of Btk?

Answer: State and federal law prohibits the release of the information without the manufacturer’s release. The rationale for this law is that other manufacturers could then replicate the product. However, the law allows for public health officials -- after signing a non-disclosure agreement -- to review all ingredients of Btk and then comment in general terms about the safety of the insecticide. This has been done repeatedly in the past in Washington before Btk treatments. Local public health officials have always reported Btk doesn’t represent a serious public health risk.

Question 8: What are the advantages and disadvantages of the other five eradication methods?

Answer:

1. Mass trapping. Advantage: Target specific, and pinpoints center of population. Disadvantage: Not a proven eradication method.

2. Mating disruption. Advantage: Target specific. Disadvantages: a. Not a proven eradication method; blinds summer trapping program in treatment areas; and effective adjuvant for mating disruption not registered in Washington state.

3. Sterile insect release. Advantage: Target specific; minimal impact on environment. Disadvantage: Very expensive because it involves large rearing operation.

4. Gypchek. Advantage: Target specific. Disadvantage: Not a proven eradication method; most effective with high populations, not low populations.

5. Dimlin. Advantage: Proven eradication method. Disadvantages: a. Very persistent; remains in environment for long period; and toxic to many non-target insects.

Question 9: Why are so many people in general opposed to Btk?

Answer: People opposed to Btk are small in number. A handful of activists are opposed, usually because they are misinformed about the damage and biology of the gypsy moth, or the effects of Btk, or have chosen to ignore the information.

Question 10: Why were so many Seattle residents opposed to Btk treatments in Ballard/Magnolia in 2000 and Crown Hill neighborhood in 2002?

Answer: The vast majority of Seattle residents were very supportive of the treatments. A handful of activists were opposed, not the residents.

Question 11: What does WSDA say to a citizen who calls and asks how they can stop a Btk treatment?

Answer: We first listen to their concerns and try to answer their questions. Then we try to inform them about the damage and biology of the gypsy moth, the effectiveness and proven safety record of Btk, and ask them to support - not oppose - the treatment.